Cleanup: move Alembic, AVI, Collada, and USD to `source/blender/io`

This moves the `alembic`, `avi`, `collada`, and `usd` modules into a common
`io` directory.

This also cleans up some `#include "../../{somedir}/{somefile}.h"` by
adding `../../io/{somedir}` to `CMakeLists.txt` and then just using
`#include "{somefile}.h"`.

No functional changes.

22 files changed, 0 insertions, 2952 deletions

diff --git a/source/blender/usd/CMakeLists.txt b/source/blender/usd/CMakeLists.txt
deleted file mode 100644
index d85b3cfe4e5..00000000000
--- a/source/blender/usd/CMakeLists.txt
+++ /dev/null
@@ -1,111 +0,0 @@
-# ***** BEGIN GPL LICENSE BLOCK *****
-#
-# This program is free software; you can redistribute it and/or
-# modify it under the terms of the GNU General Public License
-# as published by the Free Software Foundation; either version 2
-# of the License, or (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program; if not, write to the Free Software Foundation,
-# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
-#
-# The Original Code is Copyright (C) 2019, Blender Foundation
-# All rights reserved.
-# ***** END GPL LICENSE BLOCK *****
-
-# This suppresses the warning "This file includes at least one deprecated or antiquated
-# header which may be removed without further notice at a future date", which is caused
-# by the USD library including <ext/hash_set> on Linux. This has been reported at:
-# https://github.com/PixarAnimationStudios/USD/issues/1057.
-if(UNIX AND NOT APPLE)
-  add_definitions(-D_GLIBCXX_PERMIT_BACKWARD_HASH)
-endif()
-if(WIN32)
-  add_definitions(-DNOMINMAX -DWIN32_LEAN_AND_MEAN)
-endif()
-add_definitions(-DPXR_STATIC)
-
-set(INC
-  .
-  ../blenkernel
-  ../blenlib
-  ../blenloader
-  ../bmesh
-  ../depsgraph
-  ../editors/include
-  ../makesdna
-  ../makesrna
-  ../windowmanager
-  ../../../intern/guardedalloc
-  ../../../intern/utfconv
-)
-
-set(INC_SYS
-  ${USD_INCLUDE_DIRS}
-  ${BOOST_INCLUDE_DIR}
-  ${TBB_INCLUDE_DIR}
-)
-
-set(SRC
-  intern/abstract_hierarchy_iterator.cc
-  intern/usd_capi.cc
-  intern/usd_hierarchy_iterator.cc
-  intern/usd_writer_abstract.cc
-  intern/usd_writer_camera.cc
-  intern/usd_writer_hair.cc
-  intern/usd_writer_light.cc
-  intern/usd_writer_mesh.cc
-  intern/usd_writer_metaball.cc
-  intern/usd_writer_transform.cc
-
-  usd.h
-  intern/abstract_hierarchy_iterator.h
-  intern/usd_exporter_context.h
-  intern/usd_hierarchy_iterator.h
-  intern/usd_writer_abstract.h
-  intern/usd_writer_camera.h
-  intern/usd_writer_hair.h
-  intern/usd_writer_light.h
-  intern/usd_writer_mesh.h
-  intern/usd_writer_metaball.h
-  intern/usd_writer_transform.h
-)
-
-set(LIB
-  bf_blenkernel
-  bf_blenlib
-)
-
-list(APPEND LIB
-  ${BOOST_LIBRARIES}
-)
-
-list(APPEND LIB
-)
-
-blender_add_lib(bf_usd "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")
-
-if(WIN32)
-  set_property(TARGET bf_usd APPEND_STRING PROPERTY LINK_FLAGS_DEBUG " /WHOLEARCHIVE:${USD_DEBUG_LIB}")
-  set_property(TARGET bf_usd APPEND_STRING PROPERTY LINK_FLAGS_RELEASE " /WHOLEARCHIVE:${USD_RELEASE_LIB}")
-  set_property(TARGET bf_usd APPEND_STRING PROPERTY LINK_FLAGS_RELWITHDEBINFO " /WHOLEARCHIVE:${USD_RELEASE_LIB}")
-  set_property(TARGET bf_usd APPEND_STRING PROPERTY LINK_FLAGS_MINSIZEREL " /WHOLEARCHIVE:${USD_RELEASE_LIB}")
-endif()
-
-# Source: https://github.com/PixarAnimationStudios/USD/blob/master/BUILDING.md#linking-whole-archives
-if(WIN32)
-  target_link_libraries(bf_usd INTERFACE ${USD_LIBRARIES})
-elseif(CMAKE_COMPILER_IS_GNUCXX)
-  target_link_libraries(bf_usd INTERFACE "-Wl,--whole-archive ${USD_LIBRARIES} -Wl,--no-whole-archive ${TBB_LIBRARIES}")
-elseif("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
-  target_link_libraries(bf_usd INTERFACE -Wl,-force_load ${USD_LIBRARIES})
-else()
-  message(FATAL_ERROR "Unknown how to link USD with your compiler ${CMAKE_CXX_COMPILER_ID}")
-endif()
-
-target_link_libraries(bf_usd INTERFACE ${TBB_LIBRARIES})
diff --git a/source/blender/usd/intern/abstract_hierarchy_iterator.cc b/source/blender/usd/intern/abstract_hierarchy_iterator.cc
deleted file mode 100644
index a8ed2c5f2a5..00000000000
--- a/source/blender/usd/intern/abstract_hierarchy_iterator.cc
+++ /dev/null
@@ -1,595 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#include "abstract_hierarchy_iterator.h"
-
-#include <iostream>
-#include <limits.h>
-#include <sstream>
-#include <string>
-
-extern "C" {
-#include "BKE_anim.h"
-#include "BKE_particle.h"
-
-#include "BLI_assert.h"
-#include "BLI_listbase.h"
-#include "BLI_math_matrix.h"
-
-#include "DNA_ID.h"
-#include "DNA_layer_types.h"
-#include "DNA_object_types.h"
-#include "DNA_particle_types.h"
-
-#include "DEG_depsgraph_query.h"
-}
-
-namespace USD {
-
-const HierarchyContext *HierarchyContext::root()
-{
-  return nullptr;
-}
-
-bool HierarchyContext::operator<(const HierarchyContext &other) const
-{
-  if (object != other.object) {
-    return object < other.object;
-  }
-  if (duplicator != NULL && duplicator == other.duplicator) {
-    // Only resort to string comparisons when both objects are created by the same duplicator.
-    return export_name < other.export_name;
-  }
-
-  return export_parent < other.export_parent;
-}
-
-bool HierarchyContext::is_instance() const
-{
-  return !original_export_path.empty();
-}
-void HierarchyContext::mark_as_instance_of(const std::string &reference_export_path)
-{
-  original_export_path = reference_export_path;
-}
-void HierarchyContext::mark_as_not_instanced()
-{
-  original_export_path.clear();
-}
-
-AbstractHierarchyWriter::~AbstractHierarchyWriter()
-{
-}
-
-AbstractHierarchyIterator::AbstractHierarchyIterator(Depsgraph *depsgraph)
-    : depsgraph_(depsgraph), writers_()
-{
-}
-
-AbstractHierarchyIterator::~AbstractHierarchyIterator()
-{
-}
-
-void AbstractHierarchyIterator::iterate_and_write()
-{
-  export_graph_construct();
-  connect_loose_objects();
-  export_graph_prune();
-  determine_export_paths(HierarchyContext::root());
-  determine_duplication_references(HierarchyContext::root(), "");
-  make_writers(HierarchyContext::root());
-  export_graph_clear();
-}
-
-void AbstractHierarchyIterator::release_writers()
-{
-  for (WriterMap::value_type it : writers_) {
-    delete_object_writer(it.second);
-  }
-  writers_.clear();
-}
-
-std::string AbstractHierarchyIterator::make_valid_name(const std::string &name) const
-{
-  return name;
-}
-
-std::string AbstractHierarchyIterator::get_id_name(const ID *id) const
-{
-  if (id == nullptr) {
-    return "";
-  }
-
-  return make_valid_name(std::string(id->name + 2));
-}
-
-std::string AbstractHierarchyIterator::get_object_data_path(const HierarchyContext *context) const
-{
-  BLI_assert(!context->export_path.empty());
-  BLI_assert(context->object->data);
-
-  return path_concatenate(context->export_path, get_object_data_name(context->object));
-}
-
-void AbstractHierarchyIterator::debug_print_export_graph(const ExportGraph &graph) const
-{
-  size_t total_graph_size = 0;
-  for (const ExportGraph::value_type &map_iter : graph) {
-    const DupliAndDuplicator &parent_info = map_iter.first;
-    Object *const export_parent = parent_info.first;
-    Object *const duplicator = parent_info.second;
-
-    if (duplicator != nullptr) {
-      printf("    DU %s (as dupped by %s):\n",
-             export_parent == nullptr ? "-null-" : (export_parent->id.name + 2),
-             duplicator->id.name + 2);
-    }
-    else {
-      printf("    OB %s:\n", export_parent == nullptr ? "-null-" : (export_parent->id.name + 2));
-    }
-
-    total_graph_size += map_iter.second.size();
-    for (HierarchyContext *child_ctx : map_iter.second) {
-      if (child_ctx->duplicator == nullptr) {
-        printf("       - %s%s%s\n",
-               child_ctx->object->id.name + 2,
-               child_ctx->weak_export ? " (weak)" : "",
-               child_ctx->original_export_path.size() ?
-                   (std::string("ref ") + child_ctx->original_export_path).c_str() :
-                   "");
-      }
-      else {
-        printf("       - %s (dup by %s%s) %s\n",
-               child_ctx->object->id.name + 2,
-               child_ctx->duplicator->id.name + 2,
-               child_ctx->weak_export ? ", weak" : "",
-               child_ctx->original_export_path.size() ?
-                   (std::string("ref ") + child_ctx->original_export_path).c_str() :
-                   "");
-      }
-    }
-  }
-  printf("    (Total graph size: %lu objects\n", total_graph_size);
-}
-
-void AbstractHierarchyIterator::export_graph_construct()
-{
-  Scene *scene = DEG_get_evaluated_scene(depsgraph_);
-
-  DEG_OBJECT_ITER_BEGIN (depsgraph_,
-                         object,
-                         DEG_ITER_OBJECT_FLAG_LINKED_DIRECTLY |
-                             DEG_ITER_OBJECT_FLAG_LINKED_VIA_SET) {
-    // Non-instanced objects always have their object-parent as export-parent.
-    const bool weak_export = mark_as_weak_export(object);
-    visit_object(object, object->parent, weak_export);
-
-    if (weak_export) {
-      // If a duplicator shouldn't be exported, its duplilist also shouldn't be.
-      continue;
-    }
-
-    // Export the duplicated objects instanced by this object.
-    ListBase *lb = object_duplilist(depsgraph_, scene, object);
-    if (lb) {
-      // Construct the set of duplicated objects, so that later we can determine whether a parent
-      // is also duplicated itself.
-      std::set<Object *> dupli_set;
-      LISTBASE_FOREACH (DupliObject *, dupli_object, lb) {
-        if (!should_visit_dupli_object(dupli_object)) {
-          continue;
-        }
-        dupli_set.insert(dupli_object->ob);
-      }
-
-      LISTBASE_FOREACH (DupliObject *, dupli_object, lb) {
-        if (!should_visit_dupli_object(dupli_object)) {
-          continue;
-        }
-
-        visit_dupli_object(dupli_object, object, dupli_set);
-      }
-    }
-
-    free_object_duplilist(lb);
-  }
-  DEG_OBJECT_ITER_END;
-}
-
-void AbstractHierarchyIterator::connect_loose_objects()
-{
-  // Find those objects whose parent is not part of the export graph; these
-  // objects would be skipped when traversing the graph as a hierarchy.
-  // These objects will have to be re-attached to some parent object in order to
-  // fit into the hierarchy.
-  ExportGraph loose_objects_graph = export_graph_;
-  for (const ExportGraph::value_type &map_iter : export_graph_) {
-    for (const HierarchyContext *child : map_iter.second) {
-      // An object that is marked as a child of another object is not considered 'loose'.
-      loose_objects_graph.erase(std::make_pair(child->object, child->duplicator));
-    }
-  }
-  // The root of the hierarchy is always found, so it's never considered 'loose'.
-  loose_objects_graph.erase(std::make_pair(nullptr, nullptr));
-
-  // Iterate over the loose objects and connect them to their export parent.
-  for (const ExportGraph::value_type &map_iter : loose_objects_graph) {
-    const DupliAndDuplicator &export_info = map_iter.first;
-    Object *object = export_info.first;
-    Object *export_parent = object->parent;
-
-    while (true) {
-      // Loose objects will all be real objects, as duplicated objects always have
-      // their duplicator or other exported duplicated object as ancestor.
-      ExportGraph::iterator found_parent_iter = export_graph_.find(
-          std::make_pair(export_parent, nullptr));
-
-      visit_object(object, export_parent, true);
-      if (found_parent_iter != export_graph_.end()) {
-        break;
-      }
-      // 'export_parent' will never be nullptr here, as the export graph contains the
-      // tuple <nullptr, nullptr> as root and thus will cause a break.
-      BLI_assert(export_parent != nullptr);
-
-      object = export_parent;
-      export_parent = export_parent->parent;
-    }
-  }
-}
-
-static bool remove_weak_subtrees(const HierarchyContext *context,
-                                 AbstractHierarchyIterator::ExportGraph &clean_graph,
-                                 const AbstractHierarchyIterator::ExportGraph &input_graph)
-{
-  bool all_is_weak = context != nullptr && context->weak_export;
-  Object *object = context != nullptr ? context->object : nullptr;
-  Object *duplicator = context != nullptr ? context->duplicator : nullptr;
-
-  const AbstractHierarchyIterator::DupliAndDuplicator map_key = std::make_pair(object, duplicator);
-  AbstractHierarchyIterator::ExportGraph::const_iterator child_iterator;
-
-  child_iterator = input_graph.find(map_key);
-  if (child_iterator != input_graph.end()) {
-    for (HierarchyContext *child_context : child_iterator->second) {
-      bool child_tree_is_weak = remove_weak_subtrees(child_context, clean_graph, input_graph);
-      all_is_weak &= child_tree_is_weak;
-
-      if (child_tree_is_weak) {
-        // This subtree is all weak, so we can remove it from the current object's children.
-        clean_graph[map_key].erase(child_context);
-        delete child_context;
-      }
-    }
-  }
-
-  if (all_is_weak) {
-    // This node and all its children are weak, so it can be removed from the export graph.
-    clean_graph.erase(map_key);
-  }
-
-  return all_is_weak;
-}
-
-void AbstractHierarchyIterator::export_graph_prune()
-{
-  // Take a copy of the map so that we can modify while recursing.
-  ExportGraph unpruned_export_graph = export_graph_;
-  remove_weak_subtrees(HierarchyContext::root(), export_graph_, unpruned_export_graph);
-}
-
-void AbstractHierarchyIterator::export_graph_clear()
-{
-  for (ExportGraph::iterator::value_type &it : export_graph_) {
-    for (HierarchyContext *context : it.second) {
-      delete context;
-    }
-  }
-  export_graph_.clear();
-}
-
-void AbstractHierarchyIterator::visit_object(Object *object,
-                                             Object *export_parent,
-                                             bool weak_export)
-{
-  HierarchyContext *context = new HierarchyContext();
-  context->object = object;
-  context->export_name = get_object_name(object);
-  context->export_parent = export_parent;
-  context->duplicator = nullptr;
-  context->weak_export = weak_export;
-  context->animation_check_include_parent = false;
-  context->export_path = "";
-  context->original_export_path = "";
-  copy_m4_m4(context->matrix_world, object->obmat);
-
-  export_graph_[std::make_pair(export_parent, nullptr)].insert(context);
-}
-
-void AbstractHierarchyIterator::visit_dupli_object(DupliObject *dupli_object,
-                                                   Object *duplicator,
-                                                   const std::set<Object *> &dupli_set)
-{
-  ExportGraph::key_type graph_index;
-  bool animation_check_include_parent = false;
-
-  HierarchyContext *context = new HierarchyContext();
-  context->object = dupli_object->ob;
-  context->duplicator = duplicator;
-  context->weak_export = false;
-  context->export_path = "";
-  context->original_export_path = "";
-
-  /* If the dupli-object's parent is also instanced by this object, use that as the
-   * export parent. Otherwise use the dupli-parent as export parent. */
-  Object *parent = dupli_object->ob->parent;
-  if (parent != nullptr && dupli_set.find(parent) != dupli_set.end()) {
-    // The parent object is part of the duplicated collection.
-    context->export_parent = parent;
-    graph_index = std::make_pair(parent, duplicator);
-  }
-  else {
-    /* The parent object is NOT part of the duplicated collection. This means that the world
-     * transform of this dupliobject can be influenced by objects that are not part of its
-     * export graph. */
-    animation_check_include_parent = true;
-    context->export_parent = duplicator;
-    graph_index = std::make_pair(duplicator, nullptr);
-  }
-
-  context->animation_check_include_parent = animation_check_include_parent;
-  copy_m4_m4(context->matrix_world, dupli_object->mat);
-
-  // Construct export name for the dupli-instance.
-  std::stringstream suffix_stream;
-  suffix_stream << std::hex;
-  for (int i = 0; i < MAX_DUPLI_RECUR && dupli_object->persistent_id[i] != INT_MAX; i++) {
-    suffix_stream << "-" << dupli_object->persistent_id[i];
-  }
-  context->export_name = make_valid_name(get_object_name(context->object) + suffix_stream.str());
-
-  export_graph_[graph_index].insert(context);
-}
-
-AbstractHierarchyIterator::ExportChildren &AbstractHierarchyIterator::graph_children(
-    const HierarchyContext *context)
-{
-  if (context == nullptr) {
-    return export_graph_[std::make_pair(nullptr, nullptr)];
-  }
-
-  return export_graph_[std::make_pair(context->object, context->duplicator)];
-}
-
-void AbstractHierarchyIterator::determine_export_paths(const HierarchyContext *parent_context)
-{
-  const std::string &parent_export_path = parent_context ? parent_context->export_path : "";
-
-  for (HierarchyContext *context : graph_children(parent_context)) {
-    context->export_path = path_concatenate(parent_export_path, context->export_name);
-
-    if (context->duplicator == nullptr) {
-      /* This is an original (i.e. non-instanced) object, so we should keep track of where it was
-       * exported to, just in case it gets instanced somewhere. */
-      ID *source_ob = &context->object->id;
-      duplisource_export_path_[source_ob] = context->export_path;
-
-      if (context->object->data != nullptr) {
-        ID *object_data = static_cast<ID *>(context->object->data);
-        ID *source_data = object_data;
-        duplisource_export_path_[source_data] = get_object_data_path(context);
-      }
-    }
-
-    determine_export_paths(context);
-  }
-}
-
-void AbstractHierarchyIterator::determine_duplication_references(
-    const HierarchyContext *parent_context, std::string indent)
-{
-  ExportChildren children = graph_children(parent_context);
-
-  for (HierarchyContext *context : children) {
-    if (context->duplicator != nullptr) {
-      ID *source_id = &context->object->id;
-      const ExportPathMap::const_iterator &it = duplisource_export_path_.find(source_id);
-
-      if (it == duplisource_export_path_.end()) {
-        // The original was not found, so mark this instance as "the original".
-        context->mark_as_not_instanced();
-        duplisource_export_path_[source_id] = context->export_path;
-      }
-      else {
-        context->mark_as_instance_of(it->second);
-      }
-
-      if (context->object->data) {
-        ID *source_data_id = (ID *)context->object->data;
-        const ExportPathMap::const_iterator &it = duplisource_export_path_.find(source_data_id);
-
-        if (it == duplisource_export_path_.end()) {
-          // The original was not found, so mark this instance as "original".
-          std::string data_path = get_object_data_path(context);
-          context->mark_as_not_instanced();
-          duplisource_export_path_[source_id] = context->export_path;
-          duplisource_export_path_[source_data_id] = data_path;
-        }
-      }
-    }
-
-    determine_duplication_references(context, indent + "  ");
-  }
-}
-
-void AbstractHierarchyIterator::make_writers(const HierarchyContext *parent_context)
-{
-  AbstractHierarchyWriter *transform_writer = nullptr;
-  float parent_matrix_inv_world[4][4];
-
-  if (parent_context) {
-    invert_m4_m4(parent_matrix_inv_world, parent_context->matrix_world);
-  }
-  else {
-    unit_m4(parent_matrix_inv_world);
-  }
-
-  for (HierarchyContext *context : graph_children(parent_context)) {
-    copy_m4_m4(context->parent_matrix_inv_world, parent_matrix_inv_world);
-
-    // Get or create the transform writer.
-    transform_writer = ensure_writer(context, &AbstractHierarchyIterator::create_transform_writer);
-    if (transform_writer == nullptr) {
-      // Unable to export, so there is nothing to attach any children to; just abort this entire
-      // branch of the export hierarchy.
-      return;
-    }
-
-    BLI_assert(DEG_is_evaluated_object(context->object));
-    /* XXX This can lead to too many XForms being written. For example, a camera writer can refuse
-     * to write an orthographic camera. By the time that this is known, the XForm has already been
-     * written. */
-    transform_writer->write(*context);
-
-    if (!context->weak_export) {
-      make_writers_particle_systems(context);
-      make_writer_object_data(context);
-    }
-
-    // Recurse into this object's children.
-    make_writers(context);
-  }
-
-  // TODO(Sybren): iterate over all unused writers and call unused_during_iteration() or something.
-}
-
-void AbstractHierarchyIterator::make_writer_object_data(const HierarchyContext *context)
-{
-  if (context->object->data == nullptr) {
-    return;
-  }
-
-  HierarchyContext data_context = *context;
-  data_context.export_path = get_object_data_path(context);
-
-  /* data_context.original_export_path is just a copy from the context. It points to the object,
-   * but needs to point to the object data. */
-  if (data_context.is_instance()) {
-    ID *object_data = static_cast<ID *>(context->object->data);
-    data_context.original_export_path = duplisource_export_path_[object_data];
-
-    /* If the object is marked as an instance, so should the object data. */
-    BLI_assert(data_context.is_instance());
-  }
-
-  AbstractHierarchyWriter *data_writer;
-  data_writer = ensure_writer(&data_context, &AbstractHierarchyIterator::create_data_writer);
-  if (data_writer == nullptr) {
-    return;
-  }
-
-  data_writer->write(data_context);
-}
-
-void AbstractHierarchyIterator::make_writers_particle_systems(
-    const HierarchyContext *transform_context)
-{
-  Object *object = transform_context->object;
-  ParticleSystem *psys = static_cast<ParticleSystem *>(object->particlesystem.first);
-  for (; psys; psys = psys->next) {
-    if (!psys_check_enabled(object, psys, true)) {
-      continue;
-    }
-
-    HierarchyContext hair_context = *transform_context;
-    hair_context.export_path = path_concatenate(transform_context->export_path,
-                                                get_id_name(&psys->part->id));
-    hair_context.particle_system = psys;
-
-    AbstractHierarchyWriter *writer = nullptr;
-    switch (psys->part->type) {
-      case PART_HAIR:
-        writer = ensure_writer(&hair_context, &AbstractHierarchyIterator::create_hair_writer);
-        break;
-      case PART_EMITTER:
-        writer = ensure_writer(&hair_context, &AbstractHierarchyIterator::create_particle_writer);
-        break;
-    }
-
-    if (writer != nullptr) {
-      writer->write(hair_context);
-    }
-  }
-}
-
-std::string AbstractHierarchyIterator::get_object_name(const Object *object) const
-{
-  return get_id_name(&object->id);
-}
-
-std::string AbstractHierarchyIterator::get_object_data_name(const Object *object) const
-{
-  ID *object_data = static_cast<ID *>(object->data);
-  return get_id_name(object_data);
-}
-
-AbstractHierarchyWriter *AbstractHierarchyIterator::get_writer(const std::string &export_path)
-{
-  WriterMap::iterator it = writers_.find(export_path);
-
-  if (it == writers_.end()) {
-    return nullptr;
-  }
-  return it->second;
-}
-
-AbstractHierarchyWriter *AbstractHierarchyIterator::ensure_writer(
-    HierarchyContext *context, AbstractHierarchyIterator::create_writer_func create_func)
-{
-  AbstractHierarchyWriter *writer = get_writer(context->export_path);
-  if (writer != nullptr) {
-    return writer;
-  }
-
-  writer = (this->*create_func)(context);
-  if (writer == nullptr) {
-    return nullptr;
-  }
-
-  writers_[context->export_path] = writer;
-
-  return writer;
-}
-
-std::string AbstractHierarchyIterator::path_concatenate(const std::string &parent_path,
-                                                        const std::string &child_path) const
-{
-  return parent_path + "/" + child_path;
-}
-
-bool AbstractHierarchyIterator::mark_as_weak_export(const Object * /*object*/) const
-{
-  return false;
-}
-bool AbstractHierarchyIterator::should_visit_dupli_object(const DupliObject *dupli_object) const
-{
-  // Removing dupli_object->no_draw hides things like custom bone shapes.
-  return !dupli_object->no_draw;
-}
-
-}  // namespace USD
diff --git a/source/blender/usd/intern/abstract_hierarchy_iterator.h b/source/blender/usd/intern/abstract_hierarchy_iterator.h
deleted file mode 100644
index 8bca2ddd447..00000000000
--- a/source/blender/usd/intern/abstract_hierarchy_iterator.h
+++ /dev/null
@@ -1,251 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-
-/*
- * This file contains the AbstractHierarchyIterator. It is intended for exporters for file
- * formats that concern an entire hierarchy of objects (rather than, for example, an OBJ file that
- * contains only a single mesh). Examples are Universal Scene Description (USD) and Alembic.
- * AbstractHierarchyIterator is intended to be subclassed to support concrete file formats.
- *
- * The AbstractHierarchyIterator makes a distinction between the actual object hierarchy and the
- * export hierarchy. The former is the parent/child structure in Blender, which can have multiple
- * parent-like objects. For example, a duplicated object can have both a duplicator and a parent,
- * both determining the final transform. The export hierarchy is the hierarchy as written to the
- * file, and every object has only one export-parent.
- *
- * Currently the AbstractHierarchyIterator does not make any decisions about *what* to export.
- * Selections like "selected only" or "no hair systems" are left to concrete subclasses.
- */
-
-#ifndef __ABSTRACT_HIERARCHY_ITERATOR_H__
-#define __ABSTRACT_HIERARCHY_ITERATOR_H__
-
-#include <map>
-#include <string>
-#include <set>
-
-struct Base;
-struct Depsgraph;
-struct DupliObject;
-struct ID;
-struct Object;
-struct ParticleSystem;
-struct ViewLayer;
-
-namespace USD {
-
-class AbstractHierarchyWriter;
-
-/* HierarchyContext structs are created by the AbstractHierarchyIterator. Each HierarchyContext
- * struct contains everything necessary to export a single object to a file. */
-struct HierarchyContext {
-  /*********** Determined during hierarchy iteration: ***************/
-  Object *object;
-  Object *export_parent;
-  Object *duplicator;
-  float matrix_world[4][4];
-  std::string export_name;
-
-  /* When weak_export=true, the object will be exported only as transform, and only if is an
-   * ancestor of an object with weak_export=false.
-   *
-   * In other words: when weak_export=true but this object has no children, or all decendants also
-   * have weak_export=true, this object (and by recursive reasoning all its decendants) will be
-   * excluded from the export.
-   *
-   * The export hierarchy is kept as close to the the hierarchy in Blender as possible. As such, an
-   * object that serves as a parent for another object, but which should NOT be exported itself, is
-   * exported only as transform (i.e. as empty). This happens with objects that are part of a
-   * holdout collection (which prevents them from being exported) but also parent of an exported
-   * object. */
-  bool weak_export;
-
-  /* When true, this object should check its parents for animation data when determining whether
-   * it's animated. This is necessary when a parent object in Blender is not part of the export. */
-  bool animation_check_include_parent;
-
-  /*********** Determined during writer creation: ***************/
-  float parent_matrix_inv_world[4][4];  // Inverse of the parent's world matrix.
-  std::string export_path;          // Hierarchical path, such as "/grandparent/parent/objectname".
-  ParticleSystem *particle_system;  // Only set for particle/hair writers.
-
-  /* Hierarchical path of the object this object is duplicating; only set when this object should
-   * be stored as a reference to its original. It can happen that the original is not part of the
-   * exported objects, in which case this string is empty even though 'duplicator' is set. */
-  std::string original_export_path;
-
-  bool operator<(const HierarchyContext &other) const;
-
-  /* Return a HierarchyContext representing the root of the export hierarchy. */
-  static const HierarchyContext *root();
-
-  /* For handling instanced collections, instances created by particles, etc. */
-  bool is_instance() const;
-  void mark_as_instance_of(const std::string &reference_export_path);
-  void mark_as_not_instanced();
-};
-
-/* Abstract writer for objects. Create concrete subclasses to write to USD, Alembic, etc.
- *
- * Instantiated by the AbstractHierarchyIterator on the first frame an object exists. Generally
- * that's the first frame to be exported, but can be later, for example when objects are
- * instantiated by particles. The AbstractHierarchyWriter::write() function is called on every
- * frame the object exists in the dependency graph and should be exported.
- */
-class AbstractHierarchyWriter {
- public:
-  virtual ~AbstractHierarchyWriter();
-  virtual void write(HierarchyContext &context) = 0;
-  // TODO(Sybren): add function like absent() that's called when a writer was previously created,
-  // but wasn't used while exporting the current frame (for example, a particle-instanced mesh of
-  // which the particle is no longer alive).
-};
-
-/* AbstractHierarchyIterator iterates over objects in a dependency graph, and constructs export
- * writers. These writers are then called to perform the actual writing to a USD or Alembic file.
- *
- * Dealing with file- and scene-level data (for example, creating a USD scene, setting the frame
- * rate, etc.) is not part of the AbstractHierarchyIterator class structure, and should be done
- * in separate code.
- */
-class AbstractHierarchyIterator {
- public:
-  /* Mapping from export path to writer. */
-  typedef std::map<std::string, AbstractHierarchyWriter *> WriterMap;
-  /* Pair of a (potentially duplicated) object and its duplicator (or nullptr).
-   * This is typically used to store a pair of HierarchyContext::object and
-   * HierarchyContext::duplicator. */
-  typedef std::pair<Object *, Object *> DupliAndDuplicator;
-  /* All the children of some object, as per the export hierarchy. */
-  typedef std::set<HierarchyContext *> ExportChildren;
-  /* Mapping from an object and its duplicator to the object's export-children. */
-  typedef std::map<DupliAndDuplicator, ExportChildren> ExportGraph;
-  /* Mapping from ID to its export path. This is used for instancing; given an
-   * instanced datablock, the export path of the original can be looked up. */
-  typedef std::map<ID *, std::string> ExportPathMap;
-
- protected:
-  ExportGraph export_graph_;
-  ExportPathMap duplisource_export_path_;
-  Depsgraph *depsgraph_;
-  WriterMap writers_;
-
- public:
-  explicit AbstractHierarchyIterator(Depsgraph *depsgraph);
-  virtual ~AbstractHierarchyIterator();
-
-  /* Iterate over the depsgraph, create writers, and tell the writers to write.
-   * Main entry point for the AbstractHierarchyIterator, must be called for every to-be-exported
-   * frame. */
-  void iterate_and_write();
-
-  /* Release all writers. Call after all frames have been exported. */
-  void release_writers();
-
-  /* Convert the given name to something that is valid for the exported file format.
-   * This base implementation is a no-op; override in a concrete subclass. */
-  virtual std::string make_valid_name(const std::string &name) const;
-
-  /* Return the name of this ID datablock that is valid for the exported file format. Overriding is
-   * only necessary if make_valid_name(id->name+2) is not suitable for the exported file format.
-   * NULL-safe: when `id == nullptr` this returns an empty string. */
-  virtual std::string get_id_name(const ID *id) const;
-
-  /* Given a HierarchyContext of some Object *, return an export path that is valid for its
-   * object->data. Overriding is necessary when the exported format does NOT expect the object's
-   * data to be a child of the object. */
-  virtual std::string get_object_data_path(const HierarchyContext *context) const;
-
- private:
-  void debug_print_export_graph(const ExportGraph &graph) const;
-
-  void export_graph_construct();
-  void connect_loose_objects();
-  void export_graph_prune();
-  void export_graph_clear();
-
-  void visit_object(Object *object, Object *export_parent, bool weak_export);
-  void visit_dupli_object(DupliObject *dupli_object,
-                          Object *duplicator,
-                          const std::set<Object *> &dupli_set);
-
-  ExportChildren &graph_children(const HierarchyContext *parent_context);
-
-  void determine_export_paths(const HierarchyContext *parent_context);
-  void determine_duplication_references(const HierarchyContext *parent_context,
-                                        std::string indent);
-
-  void make_writers(const HierarchyContext *parent_context);
-  void make_writer_object_data(const HierarchyContext *context);
-  void make_writers_particle_systems(const HierarchyContext *context);
-
-  /* Convenience wrappers around get_id_name(). */
-  std::string get_object_name(const Object *object) const;
-  std::string get_object_data_name(const Object *object) const;
-
-  AbstractHierarchyWriter *get_writer(const std::string &export_path);
-
-  typedef AbstractHierarchyWriter *(AbstractHierarchyIterator::*create_writer_func)(
-      const HierarchyContext *);
-  /* Ensure that a writer exists; if it doesn't, call create_func(context). The create_func
-   * function should be one of the create_XXXX_writer(context) functions declared below. */
-  AbstractHierarchyWriter *ensure_writer(HierarchyContext *context,
-                                         create_writer_func create_func);
-
- protected:
-  /* Construct a valid path for the export file format. This class concatenates by using '/' as a
-   * path separator, which is valid for both Alembic and USD. */
-  virtual std::string path_concatenate(const std::string &parent_path,
-                                       const std::string &child_path) const;
-
-  /* Return whether this object should be marked as 'weak export' or not.
-   *
-   * When this returns false, writers for the transform and data are created,
-   * and dupli-objects dupli-object generated from this object will be passed to
-   * should_visit_dupli_object().
-   *
-   * When this returns true, only a transform writer is created and marked as
-   * 'weak export'. In this case, the transform writer will be removed before
-   * exporting starts, unless a decendant of this object is to be exported.
-   * Dupli-object generated from this object will also be skipped.
-   *
-   * See HierarchyContext::weak_export.
-   */
-  virtual bool mark_as_weak_export(const Object *object) const;
-
-  virtual bool should_visit_dupli_object(const DupliObject *dupli_object) const;
-
-  /* These functions should create an AbstractHierarchyWriter subclass instance, or return
-   * nullptr if the object or its data should not be exported. Returning a nullptr for
-   * data/hair/particle will NOT prevent the transform to be written.
-   *
-   * The returned writer is owned by the AbstractHierarchyWriter, and should be freed in
-   * delete_object_writer(). */
-  virtual AbstractHierarchyWriter *create_transform_writer(const HierarchyContext *context) = 0;
-  virtual AbstractHierarchyWriter *create_data_writer(const HierarchyContext *context) = 0;
-  virtual AbstractHierarchyWriter *create_hair_writer(const HierarchyContext *context) = 0;
-  virtual AbstractHierarchyWriter *create_particle_writer(const HierarchyContext *context) = 0;
-
-  /* Called by release_writers() to free what the create_XXX_writer() functions allocated. */
-  virtual void delete_object_writer(AbstractHierarchyWriter *writer) = 0;
-};
-
-}  // namespace USD
-
-#endif /* __ABSTRACT_HIERARCHY_ITERATOR_H__ */
diff --git a/source/blender/usd/intern/usd_capi.cc b/source/blender/usd/intern/usd_capi.cc
deleted file mode 100644
index 83e11cd7bf3..00000000000
--- a/source/blender/usd/intern/usd_capi.cc
+++ /dev/null
@@ -1,233 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-
-#include "usd.h"
-#include "usd_hierarchy_iterator.h"
-
-#include <pxr/pxr.h>
-#include <pxr/usd/usd/stage.h>
-#include <pxr/usd/usdGeom/tokens.h>
-
-#include "MEM_guardedalloc.h"
-
-extern "C" {
-#include "DEG_depsgraph.h"
-#include "DEG_depsgraph_build.h"
-#include "DEG_depsgraph_query.h"
-
-#include "DNA_scene_types.h"
-
-#include "BKE_blender_version.h"
-#include "BKE_context.h"
-#include "BKE_global.h"
-#include "BKE_scene.h"
-
-#include "BLI_fileops.h"
-#include "BLI_path_util.h"
-#include "BLI_string.h"
-
-#include "WM_api.h"
-#include "WM_types.h"
-}
-
-namespace USD {
-
-struct ExportJobData {
-  ViewLayer *view_layer;
-  Main *bmain;
-  Depsgraph *depsgraph;
-  wmWindowManager *wm;
-
-  char filename[FILE_MAX];
-  USDExportParams params;
-
-  short *stop;
-  short *do_update;
-  float *progress;
-
-  bool was_canceled;
-  bool export_ok;
-};
-
-static void export_startjob(void *customdata, short *stop, short *do_update, float *progress)
-{
-  ExportJobData *data = static_cast<ExportJobData *>(customdata);
-
-  data->stop = stop;
-  data->do_update = do_update;
-  data->progress = progress;
-  data->was_canceled = false;
-
-  G.is_rendering = true;
-  WM_set_locked_interface(data->wm, true);
-  G.is_break = false;
-
-  // Construct the depsgraph for exporting.
-  Scene *scene = DEG_get_input_scene(data->depsgraph);
-  ViewLayer *view_layer = DEG_get_input_view_layer(data->depsgraph);
-  DEG_graph_build_from_view_layer(data->depsgraph, data->bmain, scene, view_layer);
-  BKE_scene_graph_update_tagged(data->depsgraph, data->bmain);
-
-  *progress = 0.0f;
-  *do_update = true;
-
-  // For restoring the current frame after exporting animation is done.
-  const int orig_frame = CFRA;
-
-  pxr::UsdStageRefPtr usd_stage = pxr::UsdStage::CreateNew(data->filename);
-  if (!usd_stage) {
-    /* This happens when the USD JSON files cannot be found. When that happens,
-     * the USD library doesn't know it has the functionality to write USDA and
-     * USDC files, and creating a new UsdStage fails. */
-    WM_reportf(
-        RPT_ERROR, "USD Export: unable to find suitable USD plugin to write %s", data->filename);
-    data->export_ok = false;
-    return;
-  }
-
-  usd_stage->SetMetadata(pxr::UsdGeomTokens->upAxis, pxr::VtValue(pxr::UsdGeomTokens->z));
-  usd_stage->SetMetadata(pxr::UsdGeomTokens->metersPerUnit,
-                         pxr::VtValue(scene->unit.scale_length));
-  usd_stage->GetRootLayer()->SetDocumentation(std::string("Blender ") + versionstr);
-
-  // Set up the stage for animated data.
-  if (data->params.export_animation) {
-    usd_stage->SetTimeCodesPerSecond(FPS);
-    usd_stage->SetStartTimeCode(scene->r.sfra);
-    usd_stage->SetEndTimeCode(scene->r.efra);
-  }
-
-  USDHierarchyIterator iter(data->depsgraph, usd_stage, data->params);
-
-  if (data->params.export_animation) {
-    // Writing the animated frames is not 100% of the work, but it's our best guess.
-    float progress_per_frame = 1.0f / std::max(1, (scene->r.efra - scene->r.sfra + 1));
-
-    for (float frame = scene->r.sfra; frame <= scene->r.efra; frame++) {
-      if (G.is_break || (stop != nullptr && *stop)) {
-        break;
-      }
-
-      // Update the scene for the next frame to render.
-      scene->r.cfra = static_cast<int>(frame);
-      scene->r.subframe = frame - scene->r.cfra;
-      BKE_scene_graph_update_for_newframe(data->depsgraph, data->bmain);
-
-      iter.set_export_frame(frame);
-      iter.iterate_and_write();
-
-      *progress += progress_per_frame;
-      *do_update = true;
-    }
-  }
-  else {
-    // If we're not animating, a single iteration over all objects is enough.
-    iter.iterate_and_write();
-  }
-
-  iter.release_writers();
-  usd_stage->GetRootLayer()->Save();
-
-  // Finish up by going back to the keyframe that was current before we started.
-  if (CFRA != orig_frame) {
-    CFRA = orig_frame;
-    BKE_scene_graph_update_for_newframe(data->depsgraph, data->bmain);
-  }
-
-  data->export_ok = !data->was_canceled;
-
-  *progress = 1.0f;
-  *do_update = true;
-}
-
-static void export_endjob(void *customdata)
-{
-  ExportJobData *data = static_cast<ExportJobData *>(customdata);
-
-  DEG_graph_free(data->depsgraph);
-
-  if (data->was_canceled && BLI_exists(data->filename)) {
-    BLI_delete(data->filename, false, false);
-  }
-
-  G.is_rendering = false;
-  WM_set_locked_interface(data->wm, false);
-}
-
-}  // namespace USD
-
-bool USD_export(bContext *C,
-                const char *filepath,
-                const USDExportParams *params,
-                bool as_background_job)
-{
-  ViewLayer *view_layer = CTX_data_view_layer(C);
-  Scene *scene = CTX_data_scene(C);
-
-  USD::ExportJobData *job = static_cast<USD::ExportJobData *>(
-      MEM_mallocN(sizeof(USD::ExportJobData), "ExportJobData"));
-
-  job->bmain = CTX_data_main(C);
-  job->wm = CTX_wm_manager(C);
-  job->export_ok = false;
-  BLI_strncpy(job->filename, filepath, sizeof(job->filename));
-
-  job->depsgraph = DEG_graph_new(job->bmain, scene, view_layer, params->evaluation_mode);
-  job->params = *params;
-
-  bool export_ok = false;
-  if (as_background_job) {
-    wmJob *wm_job = WM_jobs_get(
-        job->wm, CTX_wm_window(C), scene, "USD Export", WM_JOB_PROGRESS, WM_JOB_TYPE_ALEMBIC);
-
-    /* setup job */
-    WM_jobs_customdata_set(wm_job, job, MEM_freeN);
-    WM_jobs_timer(wm_job, 0.1, NC_SCENE | ND_FRAME, NC_SCENE | ND_FRAME);
-    WM_jobs_callbacks(wm_job, USD::export_startjob, NULL, NULL, USD::export_endjob);
-
-    WM_jobs_start(CTX_wm_manager(C), wm_job);
-  }
-  else {
-    /* Fake a job context, so that we don't need NULL pointer checks while exporting. */
-    short stop = 0, do_update = 0;
-    float progress = 0.f;
-
-    USD::export_startjob(job, &stop, &do_update, &progress);
-    USD::export_endjob(job);
-    export_ok = job->export_ok;
-
-    MEM_freeN(job);
-  }
-
-  return export_ok;
-}
-
-int USD_get_version(void)
-{
-  /* USD 19.11 defines:
-   *
-   * #define PXR_MAJOR_VERSION 0
-   * #define PXR_MINOR_VERSION 19
-   * #define PXR_PATCH_VERSION 11
-   * #define PXR_VERSION 1911
-   *
-   * So the major version is implicit/invisible in the public version number.
-   */
-  return PXR_VERSION;
-}
diff --git a/source/blender/usd/intern/usd_exporter_context.h b/source/blender/usd/intern/usd_exporter_context.h
deleted file mode 100644
index 4ae415b3d34..00000000000
--- a/source/blender/usd/intern/usd_exporter_context.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#ifndef __USD_EXPORTER_CONTEXT_H__
-#define __USD_EXPORTER_CONTEXT_H__
-
-#include "usd.h"
-
-#include <pxr/usd/sdf/path.h>
-#include <pxr/usd/usd/common.h>
-
-struct Depsgraph;
-struct Object;
-
-namespace USD {
-
-class USDHierarchyIterator;
-
-struct USDExporterContext {
-  Depsgraph *depsgraph;
-  const pxr::UsdStageRefPtr stage;
-  const pxr::SdfPath usd_path;
-  const USDHierarchyIterator *hierarchy_iterator;
-  const USDExportParams &export_params;
-};
-
-}  // namespace USD
-
-#endif /* __USD_EXPORTER_CONTEXT_H__ */
diff --git a/source/blender/usd/intern/usd_hierarchy_iterator.cc b/source/blender/usd/intern/usd_hierarchy_iterator.cc
deleted file mode 100644
index fd888f39adc..00000000000
--- a/source/blender/usd/intern/usd_hierarchy_iterator.cc
+++ /dev/null
@@ -1,150 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#include "usd.h"
-
-#include "usd_hierarchy_iterator.h"
-#include "usd_writer_abstract.h"
-#include "usd_writer_camera.h"
-#include "usd_writer_hair.h"
-#include "usd_writer_light.h"
-#include "usd_writer_mesh.h"
-#include "usd_writer_metaball.h"
-#include "usd_writer_transform.h"
-
-#include <string>
-
-#include <pxr/base/tf/stringUtils.h>
-
-extern "C" {
-#include "BKE_anim.h"
-
-#include "BLI_assert.h"
-
-#include "DEG_depsgraph_query.h"
-
-#include "DNA_ID.h"
-#include "DNA_layer_types.h"
-#include "DNA_object_types.h"
-}
-
-namespace USD {
-
-USDHierarchyIterator::USDHierarchyIterator(Depsgraph *depsgraph,
-                                           pxr::UsdStageRefPtr stage,
-                                           const USDExportParams &params)
-    : AbstractHierarchyIterator(depsgraph), stage_(stage), params_(params)
-{
-}
-
-bool USDHierarchyIterator::mark_as_weak_export(const Object *object) const
-{
-  if (params_.selected_objects_only && (object->base_flag & BASE_SELECTED) == 0) {
-    return true;
-  }
-  return false;
-}
-
-void USDHierarchyIterator::delete_object_writer(AbstractHierarchyWriter *writer)
-{
-  delete static_cast<USDAbstractWriter *>(writer);
-}
-
-std::string USDHierarchyIterator::make_valid_name(const std::string &name) const
-{
-  return pxr::TfMakeValidIdentifier(name);
-}
-
-void USDHierarchyIterator::set_export_frame(float frame_nr)
-{
-  // The USD stage is already set up to have FPS timecodes per frame.
-  export_time_ = pxr::UsdTimeCode(frame_nr);
-}
-
-const pxr::UsdTimeCode &USDHierarchyIterator::get_export_time_code() const
-{
-  return export_time_;
-}
-
-USDExporterContext USDHierarchyIterator::create_usd_export_context(const HierarchyContext *context)
-{
-  return USDExporterContext{depsgraph_, stage_, pxr::SdfPath(context->export_path), this, params_};
-}
-
-AbstractHierarchyWriter *USDHierarchyIterator::create_transform_writer(
-    const HierarchyContext *context)
-{
-  return new USDTransformWriter(create_usd_export_context(context));
-}
-
-AbstractHierarchyWriter *USDHierarchyIterator::create_data_writer(const HierarchyContext *context)
-{
-  USDExporterContext usd_export_context = create_usd_export_context(context);
-  USDAbstractWriter *data_writer = nullptr;
-
-  switch (context->object->type) {
-    case OB_MESH:
-      data_writer = new USDMeshWriter(usd_export_context);
-      break;
-    case OB_CAMERA:
-      data_writer = new USDCameraWriter(usd_export_context);
-      break;
-    case OB_LAMP:
-      data_writer = new USDLightWriter(usd_export_context);
-      break;
-    case OB_MBALL:
-      data_writer = new USDMetaballWriter(usd_export_context);
-      break;
-
-    case OB_EMPTY:
-    case OB_CURVE:
-    case OB_SURF:
-    case OB_FONT:
-    case OB_SPEAKER:
-    case OB_LIGHTPROBE:
-    case OB_LATTICE:
-    case OB_ARMATURE:
-    case OB_GPENCIL:
-      return nullptr;
-    case OB_TYPE_MAX:
-      BLI_assert(!"OB_TYPE_MAX should not be used");
-      return nullptr;
-  }
-
-  if (!data_writer->is_supported(context)) {
-    delete data_writer;
-    return nullptr;
-  }
-
-  return data_writer;
-}
-
-AbstractHierarchyWriter *USDHierarchyIterator::create_hair_writer(const HierarchyContext *context)
-{
-  if (!params_.export_hair) {
-    return nullptr;
-  }
-  return new USDHairWriter(create_usd_export_context(context));
-}
-
-AbstractHierarchyWriter *USDHierarchyIterator::create_particle_writer(const HierarchyContext *)
-{
-  return nullptr;
-}
-
-}  // namespace USD
diff --git a/source/blender/usd/intern/usd_hierarchy_iterator.h b/source/blender/usd/intern/usd_hierarchy_iterator.h
deleted file mode 100644
index 90c82c6e551..00000000000
--- a/source/blender/usd/intern/usd_hierarchy_iterator.h
+++ /dev/null
@@ -1,71 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#ifndef __USD_HIERARCHY_ITERATOR_H__
-#define __USD_HIERARCHY_ITERATOR_H__
-
-#include "abstract_hierarchy_iterator.h"
-#include "usd_exporter_context.h"
-#include "usd.h"
-
-#include <string>
-
-#include <pxr/usd/usd/common.h>
-#include <pxr/usd/usd/timeCode.h>
-
-struct Depsgraph;
-struct ID;
-struct Object;
-
-namespace USD {
-
-class USDHierarchyIterator : public AbstractHierarchyIterator {
- private:
-  const pxr::UsdStageRefPtr stage_;
-  pxr::UsdTimeCode export_time_;
-  const USDExportParams &params_;
-
- public:
-  USDHierarchyIterator(Depsgraph *depsgraph,
-                       pxr::UsdStageRefPtr stage,
-                       const USDExportParams &params);
-
-  void set_export_frame(float frame_nr);
-  const pxr::UsdTimeCode &get_export_time_code() const;
-
-  virtual std::string make_valid_name(const std::string &name) const override;
-
- protected:
-  virtual bool mark_as_weak_export(const Object *object) const override;
-
-  virtual AbstractHierarchyWriter *create_transform_writer(
-      const HierarchyContext *context) override;
-  virtual AbstractHierarchyWriter *create_data_writer(const HierarchyContext *context) override;
-  virtual AbstractHierarchyWriter *create_hair_writer(const HierarchyContext *context) override;
-  virtual AbstractHierarchyWriter *create_particle_writer(
-      const HierarchyContext *context) override;
-
-  virtual void delete_object_writer(AbstractHierarchyWriter *writer) override;
-
- private:
-  USDExporterContext create_usd_export_context(const HierarchyContext *context);
-};
-
-}  // namespace USD
-
-#endif /* __USD_HIERARCHY_ITERATOR_H__ */
diff --git a/source/blender/usd/intern/usd_writer_abstract.cc b/source/blender/usd/intern/usd_writer_abstract.cc
deleted file mode 100644
index 4d0b4364fb5..00000000000
--- a/source/blender/usd/intern/usd_writer_abstract.cc
+++ /dev/null
@@ -1,147 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#include "usd_writer_abstract.h"
-#include "usd_hierarchy_iterator.h"
-
-#include <pxr/base/tf/stringUtils.h>
-
-extern "C" {
-#include "BKE_animsys.h"
-#include "BKE_key.h"
-
-#include "DNA_modifier_types.h"
-}
-
-/* TfToken objects are not cheap to construct, so we do it once. */
-namespace usdtokens {
-// Materials
-static const pxr::TfToken diffuse_color("diffuseColor", pxr::TfToken::Immortal);
-static const pxr::TfToken metallic("metallic", pxr::TfToken::Immortal);
-static const pxr::TfToken preview_shader("previewShader", pxr::TfToken::Immortal);
-static const pxr::TfToken preview_surface("UsdPreviewSurface", pxr::TfToken::Immortal);
-static const pxr::TfToken roughness("roughness", pxr::TfToken::Immortal);
-static const pxr::TfToken surface("surface", pxr::TfToken::Immortal);
-}  // namespace usdtokens
-
-namespace USD {
-
-USDAbstractWriter::USDAbstractWriter(const USDExporterContext &usd_export_context)
-    : usd_export_context_(usd_export_context),
-      usd_value_writer_(),
-      frame_has_been_written_(false),
-      is_animated_(false)
-{
-}
-
-USDAbstractWriter::~USDAbstractWriter()
-{
-}
-
-bool USDAbstractWriter::is_supported(const HierarchyContext * /*context*/) const
-{
-  return true;
-}
-
-pxr::UsdTimeCode USDAbstractWriter::get_export_time_code() const
-{
-  if (is_animated_) {
-    return usd_export_context_.hierarchy_iterator->get_export_time_code();
-  }
-  // By using the default timecode USD won't even write a single `timeSample` for non-animated
-  // data. Instead, it writes it as non-timesampled.
-  static pxr::UsdTimeCode default_timecode = pxr::UsdTimeCode::Default();
-  return default_timecode;
-}
-
-void USDAbstractWriter::write(HierarchyContext &context)
-{
-  if (!frame_has_been_written_) {
-    is_animated_ = usd_export_context_.export_params.export_animation &&
-                   check_is_animated(context);
-  }
-  else if (!is_animated_) {
-    /* A frame has already been written, and without animation one frame is enough. */
-    return;
-  }
-
-  do_write(context);
-
-  frame_has_been_written_ = true;
-}
-
-bool USDAbstractWriter::check_is_animated(const HierarchyContext &context) const
-{
-  const Object *object = context.object;
-
-  if (BKE_animdata_id_is_animated(static_cast<ID *>(object->data))) {
-    return true;
-  }
-  if (BKE_key_from_object(object) != nullptr) {
-    return true;
-  }
-
-  /* Test modifiers. */
-  /* TODO(Sybren): replace this with a check on the depsgraph to properly check for dependency on
-   * time. */
-  ModifierData *md = static_cast<ModifierData *>(object->modifiers.first);
-  while (md) {
-    if (md->type != eModifierType_Subsurf) {
-      return true;
-    }
-    md = md->next;
-  }
-
-  return false;
-}
-
-const pxr::SdfPath &USDAbstractWriter::usd_path() const
-{
-  return usd_export_context_.usd_path;
-}
-
-pxr::UsdShadeMaterial USDAbstractWriter::ensure_usd_material(Material *material)
-{
-  static pxr::SdfPath material_library_path("/_materials");
-  pxr::UsdStageRefPtr stage = usd_export_context_.stage;
-
-  // Construct the material.
-  pxr::TfToken material_name(usd_export_context_.hierarchy_iterator->get_id_name(&material->id));
-  pxr::SdfPath usd_path = material_library_path.AppendChild(material_name);
-  pxr::UsdShadeMaterial usd_material = pxr::UsdShadeMaterial::Get(stage, usd_path);
-  if (usd_material) {
-    return usd_material;
-  }
-  usd_material = pxr::UsdShadeMaterial::Define(stage, usd_path);
-
-  // Construct the shader.
-  pxr::SdfPath shader_path = usd_path.AppendChild(usdtokens::preview_shader);
-  pxr::UsdShadeShader shader = pxr::UsdShadeShader::Define(stage, shader_path);
-  shader.CreateIdAttr(pxr::VtValue(usdtokens::preview_surface));
-  shader.CreateInput(usdtokens::diffuse_color, pxr::SdfValueTypeNames->Color3f)
-      .Set(pxr::GfVec3f(material->r, material->g, material->b));
-  shader.CreateInput(usdtokens::roughness, pxr::SdfValueTypeNames->Float).Set(material->roughness);
-  shader.CreateInput(usdtokens::metallic, pxr::SdfValueTypeNames->Float).Set(material->metallic);
-
-  // Connect the shader and the material together.
-  usd_material.CreateSurfaceOutput().ConnectToSource(shader, usdtokens::surface);
-
-  return usd_material;
-}
-
-}  // namespace USD
diff --git a/source/blender/usd/intern/usd_writer_abstract.h b/source/blender/usd/intern/usd_writer_abstract.h
deleted file mode 100644
index 835d3a42c80..00000000000
--- a/source/blender/usd/intern/usd_writer_abstract.h
+++ /dev/null
@@ -1,77 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#ifndef __USD_WRITER_ABSTRACT_H__
-#define __USD_WRITER_ABSTRACT_H__
-
-#include "usd_exporter_context.h"
-#include "abstract_hierarchy_iterator.h"
-
-#include <pxr/usd/sdf/path.h>
-#include <pxr/usd/usd/stage.h>
-#include <pxr/usd/usdShade/material.h>
-#include <pxr/usd/usdUtils/sparseValueWriter.h>
-
-#include <vector>
-
-extern "C" {
-#include "DEG_depsgraph_query.h"
-#include "DNA_material_types.h"
-}
-
-struct Material;
-struct Object;
-
-namespace USD {
-
-class USDAbstractWriter : public AbstractHierarchyWriter {
- protected:
-  const USDExporterContext usd_export_context_;
-  pxr::UsdUtilsSparseValueWriter usd_value_writer_;
-
-  bool frame_has_been_written_;
-  bool is_animated_;
-
- public:
-  USDAbstractWriter(const USDExporterContext &usd_export_context);
-  virtual ~USDAbstractWriter();
-
-  virtual void write(HierarchyContext &context) override;
-
-  /* Returns true if the data to be written is actually supported. This would, for example, allow a
-   * hypothetical camera writer accept a perspective camera but reject an orthogonal one.
-   *
-   * Returning false from a transform writer will prevent the object and all its decendants from
-   * being exported. Returning false from a data writer (object data, hair, or particles) will
-   * only prevent that data from being written (and thus cause the object to be exported as an
-   * Empty). */
-  virtual bool is_supported(const HierarchyContext *context) const;
-
-  const pxr::SdfPath &usd_path() const;
-
- protected:
-  virtual void do_write(HierarchyContext &context) = 0;
-  virtual bool check_is_animated(const HierarchyContext &context) const;
-  pxr::UsdTimeCode get_export_time_code() const;
-
-  pxr::UsdShadeMaterial ensure_usd_material(Material *material);
-};
-
-}  // namespace USD
-
-#endif /* __USD_WRITER_ABSTRACT_H__ */
diff --git a/source/blender/usd/intern/usd_writer_camera.cc b/source/blender/usd/intern/usd_writer_camera.cc
deleted file mode 100644
index 9b85d69559c..00000000000
--- a/source/blender/usd/intern/usd_writer_camera.cc
+++ /dev/null
@@ -1,111 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#include "usd_writer_camera.h"
-#include "usd_hierarchy_iterator.h"
-
-#include <pxr/usd/usdGeom/camera.h>
-#include <pxr/usd/usdGeom/tokens.h>
-
-extern "C" {
-#include "BKE_camera.h"
-#include "BLI_assert.h"
-
-#include "DNA_camera_types.h"
-#include "DNA_scene_types.h"
-}
-
-namespace USD {
-
-USDCameraWriter::USDCameraWriter(const USDExporterContext &ctx) : USDAbstractWriter(ctx)
-{
-}
-
-bool USDCameraWriter::is_supported(const HierarchyContext *context) const
-{
-  Camera *camera = static_cast<Camera *>(context->object->data);
-  return camera->type == CAM_PERSP;
-}
-
-static void camera_sensor_size_for_render(const Camera *camera,
-                                          const struct RenderData *rd,
-                                          float *r_sensor_x,
-                                          float *r_sensor_y)
-{
-  /* Compute the final image size in pixels. */
-  float sizex = rd->xsch * rd->xasp;
-  float sizey = rd->ysch * rd->yasp;
-
-  int sensor_fit = BKE_camera_sensor_fit(camera->sensor_fit, sizex, sizey);
-
-  switch (sensor_fit) {
-    case CAMERA_SENSOR_FIT_HOR:
-      *r_sensor_x = camera->sensor_x;
-      *r_sensor_y = camera->sensor_x * sizey / sizex;
-      break;
-    case CAMERA_SENSOR_FIT_VERT:
-      *r_sensor_x = camera->sensor_y * sizex / sizey;
-      *r_sensor_y = camera->sensor_y;
-      break;
-    case CAMERA_SENSOR_FIT_AUTO:
-      BLI_assert(!"Camera fit should be either horizontal or vertical");
-      break;
-  }
-}
-
-void USDCameraWriter::do_write(HierarchyContext &context)
-{
-  pxr::UsdTimeCode timecode = get_export_time_code();
-  pxr::UsdGeomCamera usd_camera = pxr::UsdGeomCamera::Define(usd_export_context_.stage,
-                                                             usd_export_context_.usd_path);
-
-  Camera *camera = static_cast<Camera *>(context.object->data);
-  Scene *scene = DEG_get_evaluated_scene(usd_export_context_.depsgraph);
-
-  usd_camera.CreateProjectionAttr().Set(pxr::UsdGeomTokens->perspective);
-
-  /* USD stores the focal length in "millimeters or tenths of world units", because at some point
-   * they decided world units might be centimeters. Quite confusing, as the USD Viewer shows the
-   * correct FoV when we write millimeters and not "tenths of world units".
-   */
-  usd_camera.CreateFocalLengthAttr().Set(camera->lens, timecode);
-
-  float aperture_x, aperture_y;
-  camera_sensor_size_for_render(camera, &scene->r, &aperture_x, &aperture_y);
-
-  float film_aspect = aperture_x / aperture_y;
-  usd_camera.CreateHorizontalApertureAttr().Set(aperture_x, timecode);
-  usd_camera.CreateVerticalApertureAttr().Set(aperture_y, timecode);
-  usd_camera.CreateHorizontalApertureOffsetAttr().Set(aperture_x * camera->shiftx, timecode);
-  usd_camera.CreateVerticalApertureOffsetAttr().Set(aperture_y * camera->shifty * film_aspect,
-                                                    timecode);
-
-  usd_camera.CreateClippingRangeAttr().Set(
-      pxr::VtValue(pxr::GfVec2f(camera->clip_start, camera->clip_end)), timecode);
-
-  // Write DoF-related attributes.
-  if (camera->dof.flag & CAM_DOF_ENABLED) {
-    usd_camera.CreateFStopAttr().Set(camera->dof.aperture_fstop, timecode);
-
-    float focus_distance = scene->unit.scale_length *
-                           BKE_camera_object_dof_distance(context.object);
-    usd_camera.CreateFocusDistanceAttr().Set(focus_distance, timecode);
-  }
-}
-
-}  // namespace USD
diff --git a/source/blender/usd/intern/usd_writer_camera.h b/source/blender/usd/intern/usd_writer_camera.h
deleted file mode 100644
index 971264ef11e..00000000000
--- a/source/blender/usd/intern/usd_writer_camera.h
+++ /dev/null
@@ -1,38 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#ifndef __USD_WRITER_CAMERA_H__
-#define __USD_WRITER_CAMERA_H__
-
-#include "usd_writer_abstract.h"
-
-namespace USD {
-
-/* Writer for writing camera data to UsdGeomCamera. */
-class USDCameraWriter : public USDAbstractWriter {
- public:
-  USDCameraWriter(const USDExporterContext &ctx);
-
- protected:
-  virtual bool is_supported(const HierarchyContext *context) const override;
-  virtual void do_write(HierarchyContext &context) override;
-};
-
-}  // namespace USD
-
-#endif /* __USD_WRITER_CAMERA_H__ */
diff --git a/source/blender/usd/intern/usd_writer_hair.cc b/source/blender/usd/intern/usd_writer_hair.cc
deleted file mode 100644
index 9251425c0b8..00000000000
--- a/source/blender/usd/intern/usd_writer_hair.cc
+++ /dev/null
@@ -1,90 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#include "usd_writer_hair.h"
-#include "usd_hierarchy_iterator.h"
-
-#include <pxr/usd/usdGeom/basisCurves.h>
-#include <pxr/usd/usdGeom/tokens.h>
-
-extern "C" {
-#include "BKE_particle.h"
-
-#include "DNA_particle_types.h"
-}
-
-namespace USD {
-
-USDHairWriter::USDHairWriter(const USDExporterContext &ctx) : USDAbstractWriter(ctx)
-{
-}
-
-void USDHairWriter::do_write(HierarchyContext &context)
-{
-  ParticleSystem *psys = context.particle_system;
-  ParticleCacheKey **cache = psys->pathcache;
-  if (cache == nullptr) {
-    return;
-  }
-
-  pxr::UsdTimeCode timecode = get_export_time_code();
-  pxr::UsdGeomBasisCurves curves = pxr::UsdGeomBasisCurves::Define(usd_export_context_.stage,
-                                                                   usd_export_context_.usd_path);
-
-  // TODO(Sybren): deal with (psys->part->flag & PART_HAIR_BSPLINE)
-  curves.CreateBasisAttr(pxr::VtValue(pxr::UsdGeomTokens->bspline));
-  curves.CreateTypeAttr(pxr::VtValue(pxr::UsdGeomTokens->cubic));
-
-  pxr::VtArray<pxr::GfVec3f> points;
-  pxr::VtIntArray curve_point_counts;
-  curve_point_counts.reserve(psys->totpart);
-
-  ParticleCacheKey *strand;
-  for (int strand_index = 0; strand_index < psys->totpart; ++strand_index) {
-    strand = cache[strand_index];
-
-    int point_count = strand->segments + 1;
-    curve_point_counts.push_back(point_count);
-
-    for (int point_index = 0; point_index < point_count; ++point_index, ++strand) {
-      points.push_back(pxr::GfVec3f(strand->co));
-    }
-  }
-
-  pxr::UsdAttribute attr_points = curves.CreatePointsAttr(pxr::VtValue(), true);
-  pxr::UsdAttribute attr_vertex_counts = curves.CreateCurveVertexCountsAttr(pxr::VtValue(), true);
-  if (!attr_points.HasValue()) {
-    attr_points.Set(points, pxr::UsdTimeCode::Default());
-    attr_vertex_counts.Set(curve_point_counts, pxr::UsdTimeCode::Default());
-  }
-  usd_value_writer_.SetAttribute(attr_points, pxr::VtValue(points), timecode);
-  usd_value_writer_.SetAttribute(attr_vertex_counts, pxr::VtValue(curve_point_counts), timecode);
-
-  if (psys->totpart > 0) {
-    pxr::VtArray<pxr::GfVec3f> colors;
-    colors.push_back(pxr::GfVec3f(cache[0]->col));
-    curves.CreateDisplayColorAttr(pxr::VtValue(colors));
-  }
-}
-
-bool USDHairWriter::check_is_animated(const HierarchyContext &) const
-{
-  return true;
-}
-
-}  // namespace USD
diff --git a/source/blender/usd/intern/usd_writer_hair.h b/source/blender/usd/intern/usd_writer_hair.h
deleted file mode 100644
index 1e882fa1654..00000000000
--- a/source/blender/usd/intern/usd_writer_hair.h
+++ /dev/null
@@ -1,38 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#ifndef __USD_WRITER_HAIR_H__
-#define __USD_WRITER_HAIR_H__
-
-#include "usd_writer_abstract.h"
-
-namespace USD {
-
-/* Writer for writing hair particle data as USD curves. */
-class USDHairWriter : public USDAbstractWriter {
- public:
-  USDHairWriter(const USDExporterContext &ctx);
-
- protected:
-  virtual void do_write(HierarchyContext &context) override;
-  virtual bool check_is_animated(const HierarchyContext &context) const override;
-};
-
-}  // namespace USD
-
-#endif /* __USD_WRITER_HAIR_H__ */
diff --git a/source/blender/usd/intern/usd_writer_light.cc b/source/blender/usd/intern/usd_writer_light.cc
deleted file mode 100644
index e13e2c58a79..00000000000
--- a/source/blender/usd/intern/usd_writer_light.cc
+++ /dev/null
@@ -1,112 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#include "usd_writer_light.h"
-#include "usd_hierarchy_iterator.h"
-
-#include <pxr/usd/usdLux/diskLight.h>
-#include <pxr/usd/usdLux/distantLight.h>
-#include <pxr/usd/usdLux/rectLight.h>
-#include <pxr/usd/usdLux/sphereLight.h>
-
-extern "C" {
-#include "BLI_assert.h"
-#include "BLI_utildefines.h"
-
-#include "DNA_light_types.h"
-#include "DNA_object_types.h"
-}
-
-namespace USD {
-
-USDLightWriter::USDLightWriter(const USDExporterContext &ctx) : USDAbstractWriter(ctx)
-{
-}
-
-bool USDLightWriter::is_supported(const HierarchyContext *context) const
-{
-  Light *light = static_cast<Light *>(context->object->data);
-  return ELEM(light->type, LA_AREA, LA_LOCAL, LA_SUN);
-}
-
-void USDLightWriter::do_write(HierarchyContext &context)
-{
-  pxr::UsdStageRefPtr stage = usd_export_context_.stage;
-  const pxr::SdfPath &usd_path = usd_export_context_.usd_path;
-  pxr::UsdTimeCode timecode = get_export_time_code();
-
-  Light *light = static_cast<Light *>(context.object->data);
-  pxr::UsdLuxLight usd_light;
-
-  switch (light->type) {
-    case LA_AREA:
-      switch (light->area_shape) {
-        case LA_AREA_DISK:
-        case LA_AREA_ELLIPSE: { /* An ellipse light will deteriorate into a disk light. */
-          pxr::UsdLuxDiskLight disk_light = pxr::UsdLuxDiskLight::Define(stage, usd_path);
-          disk_light.CreateRadiusAttr().Set(light->area_size, timecode);
-          usd_light = disk_light;
-          break;
-        }
-        case LA_AREA_RECT: {
-          pxr::UsdLuxRectLight rect_light = pxr::UsdLuxRectLight::Define(stage, usd_path);
-          rect_light.CreateWidthAttr().Set(light->area_size, timecode);
-          rect_light.CreateHeightAttr().Set(light->area_sizey, timecode);
-          usd_light = rect_light;
-          break;
-        }
-        case LA_AREA_SQUARE: {
-          pxr::UsdLuxRectLight rect_light = pxr::UsdLuxRectLight::Define(stage, usd_path);
-          rect_light.CreateWidthAttr().Set(light->area_size, timecode);
-          rect_light.CreateHeightAttr().Set(light->area_size, timecode);
-          usd_light = rect_light;
-          break;
-        }
-      }
-      break;
-    case LA_LOCAL: {
-      pxr::UsdLuxSphereLight sphere_light = pxr::UsdLuxSphereLight::Define(stage, usd_path);
-      sphere_light.CreateRadiusAttr().Set(light->area_size, timecode);
-      usd_light = sphere_light;
-      break;
-    }
-    case LA_SUN:
-      usd_light = pxr::UsdLuxDistantLight::Define(stage, usd_path);
-      break;
-    default:
-      BLI_assert(!"is_supported() returned true for unsupported light type");
-  }
-
-  /* Scale factor to get to somewhat-similar illumination. Since the USDViewer had similar
-   * over-exposure as Blender Internal with the same values, this code applies the reverse of the
-   * versioning code in light_emission_unify(). */
-  float usd_intensity;
-  if (light->type == LA_SUN) {
-    /* Untested, as the Hydra GL viewport of USDViewer doesn't support distant lights. */
-    usd_intensity = light->energy;
-  }
-  else {
-    usd_intensity = light->energy / 100.f;
-  }
-  usd_light.CreateIntensityAttr().Set(usd_intensity, timecode);
-
-  usd_light.CreateColorAttr().Set(pxr::GfVec3f(light->r, light->g, light->b), timecode);
-  usd_light.CreateSpecularAttr().Set(light->spec_fac, timecode);
-}
-
-}  // namespace USD
diff --git a/source/blender/usd/intern/usd_writer_light.h b/source/blender/usd/intern/usd_writer_light.h
deleted file mode 100644
index 349c034b6bc..00000000000
--- a/source/blender/usd/intern/usd_writer_light.h
+++ /dev/null
@@ -1,37 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#ifndef __USD_WRITER_LIGHT_H__
-#define __USD_WRITER_LIGHT_H__
-
-#include "usd_writer_abstract.h"
-
-namespace USD {
-
-class USDLightWriter : public USDAbstractWriter {
- public:
-  USDLightWriter(const USDExporterContext &ctx);
-
- protected:
-  virtual bool is_supported(const HierarchyContext *context) const override;
-  virtual void do_write(HierarchyContext &context) override;
-};
-
-}  // namespace USD
-
-#endif /* __USD_WRITER_LIGHT_H__ */
diff --git a/source/blender/usd/intern/usd_writer_mesh.cc b/source/blender/usd/intern/usd_writer_mesh.cc
deleted file mode 100644
index 74005afaf31..00000000000
--- a/source/blender/usd/intern/usd_writer_mesh.cc
+++ /dev/null
@@ -1,489 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#include "usd_writer_mesh.h"
-#include "usd_hierarchy_iterator.h"
-
-#include <pxr/usd/usdGeom/mesh.h>
-#include <pxr/usd/usdShade/material.h>
-#include <pxr/usd/usdShade/materialBindingAPI.h>
-
-extern "C" {
-#include "BLI_assert.h"
-#include "BLI_math_vector.h"
-
-#include "BKE_anim.h"
-#include "BKE_customdata.h"
-#include "BKE_lib_id.h"
-#include "BKE_material.h"
-#include "BKE_mesh.h"
-#include "BKE_modifier.h"
-#include "BKE_object.h"
-
-#include "DEG_depsgraph.h"
-
-#include "DNA_layer_types.h"
-#include "DNA_mesh_types.h"
-#include "DNA_meshdata_types.h"
-#include "DNA_modifier_types.h"
-#include "DNA_object_fluidsim_types.h"
-#include "DNA_particle_types.h"
-}
-
-namespace USD {
-
-USDGenericMeshWriter::USDGenericMeshWriter(const USDExporterContext &ctx) : USDAbstractWriter(ctx)
-{
-}
-
-bool USDGenericMeshWriter::is_supported(const HierarchyContext *context) const
-{
-  Object *object = context->object;
-  bool is_dupli = context->duplicator != nullptr;
-  int base_flag;
-
-  if (is_dupli) {
-    /* Construct the object's base flags from its dupliparent, just like is done in
-     * deg_objects_dupli_iterator_next(). Without this, the visibility check below will fail. Doing
-     * this here, instead of a more suitable location in AbstractHierarchyIterator, prevents
-     * copying the Object for every dupli. */
-    base_flag = object->base_flag;
-    object->base_flag = context->duplicator->base_flag | BASE_FROM_DUPLI;
-  }
-
-  int visibility = BKE_object_visibility(object,
-                                         usd_export_context_.export_params.evaluation_mode);
-
-  if (is_dupli) {
-    object->base_flag = base_flag;
-  }
-
-  return (visibility & OB_VISIBLE_SELF) != 0;
-}
-
-void USDGenericMeshWriter::do_write(HierarchyContext &context)
-{
-  Object *object_eval = context.object;
-  bool needsfree = false;
-  Mesh *mesh = get_export_mesh(object_eval, needsfree);
-
-  if (mesh == NULL) {
-    return;
-  }
-
-  try {
-    write_mesh(context, mesh);
-
-    if (needsfree) {
-      free_export_mesh(mesh);
-    }
-  }
-  catch (...) {
-    if (needsfree) {
-      free_export_mesh(mesh);
-    }
-    throw;
-  }
-}
-
-void USDGenericMeshWriter::free_export_mesh(Mesh *mesh)
-{
-  BKE_id_free(NULL, mesh);
-}
-
-struct USDMeshData {
-  pxr::VtArray<pxr::GfVec3f> points;
-  pxr::VtIntArray face_vertex_counts;
-  pxr::VtIntArray face_indices;
-  std::map<short, pxr::VtIntArray> face_groups;
-
-  /* The length of this array specifies the number of creases on the surface. Each element gives
-   * the number of (must be adjacent) vertices in each crease, whose indices are linearly laid out
-   * in the 'creaseIndices' attribute. Since each crease must be at least one edge long, each
-   * element of this array should be greater than one. */
-  pxr::VtIntArray crease_lengths;
-  /* The indices of all vertices forming creased edges. The size of this array must be equal to the
-   * sum of all elements of the 'creaseLengths' attribute. */
-  pxr::VtIntArray crease_vertex_indices;
-  /* The per-crease or per-edge sharpness for all creases (Usd.Mesh.SHARPNESS_INFINITE for a
-   * perfectly sharp crease). Since 'creaseLengths' encodes the number of vertices in each crease,
-   * the number of elements in this array will be either len(creaseLengths) or the sum over all X
-   * of (creaseLengths[X] - 1). Note that while the RI spec allows each crease to have either a
-   * single sharpness or a value per-edge, USD will encode either a single sharpness per crease on
-   * a mesh, or sharpnesses for all edges making up the creases on a mesh. */
-  pxr::VtFloatArray crease_sharpnesses;
-};
-
-void USDGenericMeshWriter::write_uv_maps(const Mesh *mesh, pxr::UsdGeomMesh usd_mesh)
-{
-  pxr::UsdTimeCode timecode = get_export_time_code();
-
-  const CustomData *ldata = &mesh->ldata;
-  for (int layer_idx = 0; layer_idx < ldata->totlayer; layer_idx++) {
-    const CustomDataLayer *layer = &ldata->layers[layer_idx];
-    if (layer->type != CD_MLOOPUV) {
-      continue;
-    }
-
-    /* UV coordinates are stored in a Primvar on the Mesh, and can be referenced from materials.
-     * The primvar name is the same as the UV Map name. This is to allow the standard name "st"
-     * for texture coordinates by naming the UV Map as such, without having to guess which UV Map
-     * is the "standard" one. */
-    pxr::TfToken primvar_name(pxr::TfMakeValidIdentifier(layer->name));
-    pxr::UsdGeomPrimvar uv_coords_primvar = usd_mesh.CreatePrimvar(
-        primvar_name, pxr::SdfValueTypeNames->TexCoord2fArray, pxr::UsdGeomTokens->faceVarying);
-
-    MLoopUV *mloopuv = static_cast<MLoopUV *>(layer->data);
-    pxr::VtArray<pxr::GfVec2f> uv_coords;
-    for (int loop_idx = 0; loop_idx < mesh->totloop; loop_idx++) {
-      uv_coords.push_back(pxr::GfVec2f(mloopuv[loop_idx].uv));
-    }
-
-    if (!uv_coords_primvar.HasValue()) {
-      uv_coords_primvar.Set(uv_coords, pxr::UsdTimeCode::Default());
-    }
-    const pxr::UsdAttribute &uv_coords_attr = uv_coords_primvar.GetAttr();
-    usd_value_writer_.SetAttribute(uv_coords_attr, pxr::VtValue(uv_coords), timecode);
-  }
-}
-
-void USDGenericMeshWriter::write_mesh(HierarchyContext &context, Mesh *mesh)
-{
-  pxr::UsdTimeCode timecode = get_export_time_code();
-  pxr::UsdTimeCode defaultTime = pxr::UsdTimeCode::Default();
-  pxr::UsdStageRefPtr stage = usd_export_context_.stage;
-  const pxr::SdfPath &usd_path = usd_export_context_.usd_path;
-
-  pxr::UsdGeomMesh usd_mesh = pxr::UsdGeomMesh::Define(stage, usd_path);
-  USDMeshData usd_mesh_data;
-  get_geometry_data(mesh, usd_mesh_data);
-
-  if (usd_export_context_.export_params.use_instancing && context.is_instance()) {
-    // This object data is instanced, just reference the original instead of writing a copy.
-    if (context.export_path == context.original_export_path) {
-      printf("USD ref error: export path is reference path: %s\n", context.export_path.c_str());
-      BLI_assert(!"USD reference error");
-      return;
-    }
-    pxr::SdfPath ref_path(context.original_export_path);
-    if (!usd_mesh.GetPrim().GetReferences().AddInternalReference(ref_path)) {
-      /* See this URL for a description fo why referencing may fail"
-       * https://graphics.pixar.com/usd/docs/api/class_usd_references.html#Usd_Failing_References
-       */
-      printf("USD Export warning: unable to add reference from %s to %s, not instancing object\n",
-             context.export_path.c_str(),
-             context.original_export_path.c_str());
-      return;
-    }
-    /* The material path will be of the form </_materials/{material name}>, which is outside the
-    subtree pointed to by ref_path. As a result, the referenced data is not allowed to point out
-    of its own subtree. It does work when we override the material with exactly the same path,
-    though.*/
-    if (usd_export_context_.export_params.export_materials) {
-      assign_materials(context, usd_mesh, usd_mesh_data.face_groups);
-    }
-    return;
-  }
-
-  pxr::UsdAttribute attr_points = usd_mesh.CreatePointsAttr(pxr::VtValue(), true);
-  pxr::UsdAttribute attr_face_vertex_counts = usd_mesh.CreateFaceVertexCountsAttr(pxr::VtValue(),
-                                                                                  true);
-  pxr::UsdAttribute attr_face_vertex_indices = usd_mesh.CreateFaceVertexIndicesAttr(pxr::VtValue(),
-                                                                                    true);
-
-  if (!attr_points.HasValue()) {
-    // Provide the initial value as default. This makes USD write the value as constant if they
-    // don't change over time.
-    attr_points.Set(usd_mesh_data.points, defaultTime);
-    attr_face_vertex_counts.Set(usd_mesh_data.face_vertex_counts, defaultTime);
-    attr_face_vertex_indices.Set(usd_mesh_data.face_indices, defaultTime);
-  }
-
-  usd_value_writer_.SetAttribute(attr_points, pxr::VtValue(usd_mesh_data.points), timecode);
-  usd_value_writer_.SetAttribute(
-      attr_face_vertex_counts, pxr::VtValue(usd_mesh_data.face_vertex_counts), timecode);
-  usd_value_writer_.SetAttribute(
-      attr_face_vertex_indices, pxr::VtValue(usd_mesh_data.face_indices), timecode);
-
-  if (!usd_mesh_data.crease_lengths.empty()) {
-    pxr::UsdAttribute attr_crease_lengths = usd_mesh.CreateCreaseLengthsAttr(pxr::VtValue(), true);
-    pxr::UsdAttribute attr_crease_indices = usd_mesh.CreateCreaseIndicesAttr(pxr::VtValue(), true);
-    pxr::UsdAttribute attr_crease_sharpness = usd_mesh.CreateCreaseSharpnessesAttr(pxr::VtValue(),
-                                                                                   true);
-
-    if (!attr_crease_lengths.HasValue()) {
-      attr_crease_lengths.Set(usd_mesh_data.crease_lengths, defaultTime);
-      attr_crease_indices.Set(usd_mesh_data.crease_vertex_indices, defaultTime);
-      attr_crease_sharpness.Set(usd_mesh_data.crease_sharpnesses, defaultTime);
-    }
-
-    usd_value_writer_.SetAttribute(
-        attr_crease_lengths, pxr::VtValue(usd_mesh_data.crease_lengths), timecode);
-    usd_value_writer_.SetAttribute(
-        attr_crease_indices, pxr::VtValue(usd_mesh_data.crease_vertex_indices), timecode);
-    usd_value_writer_.SetAttribute(
-        attr_crease_sharpness, pxr::VtValue(usd_mesh_data.crease_sharpnesses), timecode);
-  }
-
-  if (usd_export_context_.export_params.export_uvmaps) {
-    write_uv_maps(mesh, usd_mesh);
-  }
-  if (usd_export_context_.export_params.export_normals) {
-    write_normals(mesh, usd_mesh);
-  }
-  write_surface_velocity(context.object, mesh, usd_mesh);
-
-  // TODO(Sybren): figure out what happens when the face groups change.
-  if (frame_has_been_written_) {
-    return;
-  }
-
-  usd_mesh.CreateSubdivisionSchemeAttr().Set(pxr::UsdGeomTokens->none);
-
-  if (usd_export_context_.export_params.export_materials) {
-    assign_materials(context, usd_mesh, usd_mesh_data.face_groups);
-  }
-}
-
-static void get_vertices(const Mesh *mesh, USDMeshData &usd_mesh_data)
-{
-  usd_mesh_data.points.reserve(mesh->totvert);
-
-  const MVert *verts = mesh->mvert;
-  for (int i = 0; i < mesh->totvert; ++i) {
-    usd_mesh_data.points.push_back(pxr::GfVec3f(verts[i].co));
-  }
-}
-
-static void get_loops_polys(const Mesh *mesh, USDMeshData &usd_mesh_data)
-{
-  /* Only construct face groups (a.k.a. geometry subsets) when we need them for material
-   * assignments. */
-  bool construct_face_groups = mesh->totcol > 1;
-
-  usd_mesh_data.face_vertex_counts.reserve(mesh->totpoly);
-  usd_mesh_data.face_indices.reserve(mesh->totloop);
-
-  MLoop *mloop = mesh->mloop;
-  MPoly *mpoly = mesh->mpoly;
-  for (int i = 0; i < mesh->totpoly; ++i, ++mpoly) {
-    MLoop *loop = mloop + mpoly->loopstart;
-    usd_mesh_data.face_vertex_counts.push_back(mpoly->totloop);
-    for (int j = 0; j < mpoly->totloop; ++j, ++loop) {
-      usd_mesh_data.face_indices.push_back(loop->v);
-    }
-
-    if (construct_face_groups) {
-      usd_mesh_data.face_groups[mpoly->mat_nr].push_back(i);
-    }
-  }
-}
-
-static void get_creases(const Mesh *mesh, USDMeshData &usd_mesh_data)
-{
-  const float factor = 1.0f / 255.0f;
-
-  MEdge *edge = mesh->medge;
-  float sharpness;
-  for (int edge_idx = 0, totedge = mesh->totedge; edge_idx < totedge; ++edge_idx, ++edge) {
-    if (edge->crease == 0) {
-      continue;
-    }
-
-    if (edge->crease == 255) {
-      sharpness = pxr::UsdGeomMesh::SHARPNESS_INFINITE;
-    }
-    else {
-      sharpness = static_cast<float>(edge->crease) * factor;
-    }
-
-    usd_mesh_data.crease_vertex_indices.push_back(edge->v1);
-    usd_mesh_data.crease_vertex_indices.push_back(edge->v2);
-    usd_mesh_data.crease_lengths.push_back(2);
-    usd_mesh_data.crease_sharpnesses.push_back(sharpness);
-  }
-}
-
-void USDGenericMeshWriter::get_geometry_data(const Mesh *mesh, USDMeshData &usd_mesh_data)
-{
-  get_vertices(mesh, usd_mesh_data);
-  get_loops_polys(mesh, usd_mesh_data);
-  get_creases(mesh, usd_mesh_data);
-}
-
-void USDGenericMeshWriter::assign_materials(const HierarchyContext &context,
-                                            pxr::UsdGeomMesh usd_mesh,
-                                            const MaterialFaceGroups &usd_face_groups)
-{
-  if (context.object->totcol == 0) {
-    return;
-  }
-
-  /* Binding a material to a geometry subset isn't supported by the Hydra GL viewport yet,
-   * which is why we always bind the first material to the entire mesh. See
-   * https://github.com/PixarAnimationStudios/USD/issues/542 for more info. */
-  bool mesh_material_bound = false;
-  for (short mat_num = 0; mat_num < context.object->totcol; mat_num++) {
-    Material *material = BKE_object_material_get(context.object, mat_num + 1);
-    if (material == nullptr) {
-      continue;
-    }
-
-    pxr::UsdShadeMaterial usd_material = ensure_usd_material(material);
-    usd_material.Bind(usd_mesh.GetPrim());
-
-    /* USD seems to support neither per-material nor per-face-group double-sidedness, so we just
-     * use the flag from the first non-empty material slot. */
-    usd_mesh.CreateDoubleSidedAttr(
-        pxr::VtValue((material->blend_flag & MA_BL_CULL_BACKFACE) == 0));
-
-    mesh_material_bound = true;
-    break;
-  }
-
-  if (!mesh_material_bound) {
-    /* Blender defaults to double-sided, but USD to single-sided. */
-    usd_mesh.CreateDoubleSidedAttr(pxr::VtValue(true));
-  }
-
-  if (!mesh_material_bound || usd_face_groups.size() < 2) {
-    /* Either all material slots were empty or there is only one material in use. As geometry
-     * subsets are only written when actually used to assign a material, and the mesh already has
-     * the material assigned, there is no need to continue. */
-    return;
-  }
-
-  // Define a geometry subset per material.
-  for (const MaterialFaceGroups::value_type &face_group : usd_face_groups) {
-    short material_number = face_group.first;
-    const pxr::VtIntArray &face_indices = face_group.second;
-
-    Material *material = BKE_object_material_get(context.object, material_number + 1);
-    if (material == nullptr) {
-      continue;
-    }
-
-    pxr::UsdShadeMaterial usd_material = ensure_usd_material(material);
-    pxr::TfToken material_name = usd_material.GetPath().GetNameToken();
-
-    pxr::UsdShadeMaterialBindingAPI api = pxr::UsdShadeMaterialBindingAPI(usd_mesh);
-    pxr::UsdGeomSubset usd_face_subset = api.CreateMaterialBindSubset(material_name, face_indices);
-    usd_material.Bind(usd_face_subset.GetPrim());
-  }
-}
-
-void USDGenericMeshWriter::write_normals(const Mesh *mesh, pxr::UsdGeomMesh usd_mesh)
-{
-  pxr::UsdTimeCode timecode = get_export_time_code();
-  const float(*lnors)[3] = static_cast<float(*)[3]>(CustomData_get_layer(&mesh->ldata, CD_NORMAL));
-
-  pxr::VtVec3fArray loop_normals;
-  loop_normals.reserve(mesh->totloop);
-
-  if (lnors != nullptr) {
-    /* Export custom loop normals. */
-    for (int loop_idx = 0, totloop = mesh->totloop; loop_idx < totloop; ++loop_idx) {
-      loop_normals.push_back(pxr::GfVec3f(lnors[loop_idx]));
-    }
-  }
-  else {
-    /* Compute the loop normals based on the 'smooth' flag. */
-    float normal[3];
-    MPoly *mpoly = mesh->mpoly;
-    const MVert *mvert = mesh->mvert;
-    for (int poly_idx = 0, totpoly = mesh->totpoly; poly_idx < totpoly; ++poly_idx, ++mpoly) {
-      MLoop *mloop = mesh->mloop + mpoly->loopstart;
-
-      if ((mpoly->flag & ME_SMOOTH) == 0) {
-        /* Flat shaded, use common normal for all verts. */
-        BKE_mesh_calc_poly_normal(mpoly, mloop, mvert, normal);
-        pxr::GfVec3f pxr_normal(normal);
-        for (int loop_idx = 0; loop_idx < mpoly->totloop; ++loop_idx) {
-          loop_normals.push_back(pxr_normal);
-        }
-      }
-      else {
-        /* Smooth shaded, use individual vert normals. */
-        for (int loop_idx = 0; loop_idx < mpoly->totloop; ++loop_idx, ++mloop) {
-          normal_short_to_float_v3(normal, mvert[mloop->v].no);
-          loop_normals.push_back(pxr::GfVec3f(normal));
-        }
-      }
-    }
-  }
-
-  pxr::UsdAttribute attr_normals = usd_mesh.CreateNormalsAttr(pxr::VtValue(), true);
-  if (!attr_normals.HasValue()) {
-    attr_normals.Set(loop_normals, pxr::UsdTimeCode::Default());
-  }
-  usd_value_writer_.SetAttribute(attr_normals, pxr::VtValue(loop_normals), timecode);
-  usd_mesh.SetNormalsInterpolation(pxr::UsdGeomTokens->faceVarying);
-}
-
-void USDGenericMeshWriter::write_surface_velocity(Object *object,
-                                                  const Mesh *mesh,
-                                                  pxr::UsdGeomMesh usd_mesh)
-{
-  /* Only velocities from the fluid simulation are exported. This is the most important case,
-   * though, as the baked mesh changes topology all the time, and thus computing the velocities
-   * at import time in a post-processing step is hard. */
-  ModifierData *md = modifiers_findByType(object, eModifierType_Fluidsim);
-  if (md == nullptr) {
-    return;
-  }
-
-  /* Check that the fluid sim modifier is enabled and has useful data. */
-  const bool use_render = (DEG_get_mode(usd_export_context_.depsgraph) == DAG_EVAL_RENDER);
-  const ModifierMode required_mode = use_render ? eModifierMode_Render : eModifierMode_Realtime;
-  const Scene *scene = DEG_get_evaluated_scene(usd_export_context_.depsgraph);
-  if (!modifier_isEnabled(scene, md, required_mode)) {
-    return;
-  }
-  FluidsimModifierData *fsmd = reinterpret_cast<FluidsimModifierData *>(md);
-  if (!fsmd->fss || fsmd->fss->type != OB_FLUIDSIM_DOMAIN) {
-    return;
-  }
-  FluidsimSettings *fss = fsmd->fss;
-  if (!fss->meshVelocities) {
-    return;
-  }
-
-  /* Export per-vertex velocity vectors. */
-  pxr::VtVec3fArray usd_velocities;
-  usd_velocities.reserve(mesh->totvert);
-
-  FluidVertexVelocity *mesh_velocities = fss->meshVelocities;
-  for (int vertex_idx = 0, totvert = mesh->totvert; vertex_idx < totvert;
-       ++vertex_idx, ++mesh_velocities) {
-    usd_velocities.push_back(pxr::GfVec3f(mesh_velocities->vel));
-  }
-
-  pxr::UsdTimeCode timecode = get_export_time_code();
-  usd_mesh.CreateVelocitiesAttr().Set(usd_velocities, timecode);
-}
-
-USDMeshWriter::USDMeshWriter(const USDExporterContext &ctx) : USDGenericMeshWriter(ctx)
-{
-}
-
-Mesh *USDMeshWriter::get_export_mesh(Object *object_eval, bool & /*r_needsfree*/)
-{
-  return BKE_object_get_evaluated_mesh(object_eval);
-}
-
-}  // namespace USD
diff --git a/source/blender/usd/intern/usd_writer_mesh.h b/source/blender/usd/intern/usd_writer_mesh.h
deleted file mode 100644
index 4175e2b7e27..00000000000
--- a/source/blender/usd/intern/usd_writer_mesh.h
+++ /dev/null
@@ -1,66 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#ifndef __USD_WRITER_MESH_H__
-#define __USD_WRITER_MESH_H__
-
-#include "usd_writer_abstract.h"
-
-#include <pxr/usd/usdGeom/mesh.h>
-
-namespace USD {
-
-struct USDMeshData;
-
-/* Writer for USD geometry. Does not assume the object is a mesh object. */
-class USDGenericMeshWriter : public USDAbstractWriter {
- public:
-  USDGenericMeshWriter(const USDExporterContext &ctx);
-
- protected:
-  virtual bool is_supported(const HierarchyContext *context) const override;
-  virtual void do_write(HierarchyContext &context) override;
-
-  virtual Mesh *get_export_mesh(Object *object_eval, bool &r_needsfree) = 0;
-  virtual void free_export_mesh(Mesh *mesh);
-
- private:
-  /* Mapping from material slot number to array of face indices with that material. */
-  typedef std::map<short, pxr::VtIntArray> MaterialFaceGroups;
-
-  void write_mesh(HierarchyContext &context, Mesh *mesh);
-  void get_geometry_data(const Mesh *mesh, struct USDMeshData &usd_mesh_data);
-  void assign_materials(const HierarchyContext &context,
-                        pxr::UsdGeomMesh usd_mesh,
-                        const MaterialFaceGroups &usd_face_groups);
-  void write_uv_maps(const Mesh *mesh, pxr::UsdGeomMesh usd_mesh);
-  void write_normals(const Mesh *mesh, pxr::UsdGeomMesh usd_mesh);
-  void write_surface_velocity(Object *object, const Mesh *mesh, pxr::UsdGeomMesh usd_mesh);
-};
-
-class USDMeshWriter : public USDGenericMeshWriter {
- public:
-  USDMeshWriter(const USDExporterContext &ctx);
-
- protected:
-  virtual Mesh *get_export_mesh(Object *object_eval, bool &r_needsfree) override;
-};
-
-}  // namespace USD
-
-#endif /* __USD_WRITER_MESH_H__ */
diff --git a/source/blender/usd/intern/usd_writer_metaball.cc b/source/blender/usd/intern/usd_writer_metaball.cc
deleted file mode 100644
index 25b216d20f3..00000000000
--- a/source/blender/usd/intern/usd_writer_metaball.cc
+++ /dev/null
@@ -1,81 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2020 Blender Foundation.
- * All rights reserved.
- */
-#include "usd_writer_metaball.h"
-#include "usd_hierarchy_iterator.h"
-
-#include <pxr/usd/usdGeom/mesh.h>
-#include <pxr/usd/usdShade/material.h>
-#include <pxr/usd/usdShade/materialBindingAPI.h>
-
-extern "C" {
-#include "BLI_assert.h"
-
-#include "BKE_displist.h"
-#include "BKE_lib_id.h"
-#include "BKE_mball.h"
-#include "BKE_mesh.h"
-#include "BKE_object.h"
-
-#include "DNA_mesh_types.h"
-#include "DNA_meta_types.h"
-}
-
-namespace USD {
-
-USDMetaballWriter::USDMetaballWriter(const USDExporterContext &ctx) : USDGenericMeshWriter(ctx)
-{
-}
-
-bool USDMetaballWriter::is_supported(const HierarchyContext *context) const
-{
-  Scene *scene = DEG_get_input_scene(usd_export_context_.depsgraph);
-  return is_basis_ball(scene, context->object) && USDGenericMeshWriter::is_supported(context);
-}
-
-bool USDMetaballWriter::check_is_animated(const HierarchyContext & /*context*/) const
-{
-  /* We assume that metaballs are always animated, as the current object may
-   * not be animated but another ball in the same group may be. */
-  return true;
-}
-
-Mesh *USDMetaballWriter::get_export_mesh(Object *object_eval, bool &r_needsfree)
-{
-  Mesh *mesh_eval = BKE_object_get_evaluated_mesh(object_eval);
-  if (mesh_eval != nullptr) {
-    /* Mesh_eval only exists when generative modifiers are in use. */
-    r_needsfree = false;
-    return mesh_eval;
-  }
-  r_needsfree = true;
-  return BKE_mesh_new_from_object(usd_export_context_.depsgraph, object_eval, false);
-}
-
-void USDMetaballWriter::free_export_mesh(Mesh *mesh)
-{
-  BKE_id_free(nullptr, mesh);
-}
-
-bool USDMetaballWriter::is_basis_ball(Scene *scene, Object *ob) const
-{
-  Object *basis_ob = BKE_mball_basis_find(scene, ob);
-  return ob == basis_ob;
-}
-
-}  // namespace USD
diff --git a/source/blender/usd/intern/usd_writer_metaball.h b/source/blender/usd/intern/usd_writer_metaball.h
deleted file mode 100644
index 1a86daae2ae..00000000000
--- a/source/blender/usd/intern/usd_writer_metaball.h
+++ /dev/null
@@ -1,42 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2020 Blender Foundation.
- * All rights reserved.
- */
-#ifndef __USD_WRITER_METABALL_H__
-#define __USD_WRITER_METABALL_H__
-
-#include "usd_writer_mesh.h"
-
-namespace USD {
-
-class USDMetaballWriter : public USDGenericMeshWriter {
- public:
-  USDMetaballWriter(const USDExporterContext &ctx);
-
- protected:
-  virtual Mesh *get_export_mesh(Object *object_eval, bool &r_needsfree) override;
-  virtual void free_export_mesh(Mesh *mesh) override;
-  virtual bool is_supported(const HierarchyContext *context) const override;
-  virtual bool check_is_animated(const HierarchyContext &context) const override;
-
- private:
-  bool is_basis_ball(Scene *scene, Object *ob) const;
-};
-
-}  // namespace USD
-
-#endif /* __USD_WRITER_METABALL_H__ */
diff --git a/source/blender/usd/intern/usd_writer_transform.cc b/source/blender/usd/intern/usd_writer_transform.cc
deleted file mode 100644
index 321b516221a..00000000000
--- a/source/blender/usd/intern/usd_writer_transform.cc
+++ /dev/null
@@ -1,64 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#include "usd_writer_transform.h"
-#include "usd_hierarchy_iterator.h"
-
-#include <pxr/base/gf/matrix4f.h>
-#include <pxr/usd/usdGeom/xform.h>
-
-extern "C" {
-#include "BKE_object.h"
-
-#include "BLI_math_matrix.h"
-
-#include "DNA_layer_types.h"
-}
-
-namespace USD {
-
-USDTransformWriter::USDTransformWriter(const USDExporterContext &ctx) : USDAbstractWriter(ctx)
-{
-}
-
-void USDTransformWriter::do_write(HierarchyContext &context)
-{
-  float parent_relative_matrix[4][4];  // The object matrix relative to the parent.
-  mul_m4_m4m4(parent_relative_matrix, context.parent_matrix_inv_world, context.matrix_world);
-
-  // Write the transform relative to the parent.
-  pxr::UsdGeomXform xform = pxr::UsdGeomXform::Define(usd_export_context_.stage,
-                                                      usd_export_context_.usd_path);
-  if (!xformOp_) {
-    xformOp_ = xform.AddTransformOp();
-  }
-  xformOp_.Set(pxr::GfMatrix4d(parent_relative_matrix), get_export_time_code());
-}
-
-bool USDTransformWriter::check_is_animated(const HierarchyContext &context) const
-{
-  if (context.duplicator != NULL) {
-    /* This object is being duplicated, so could be emitted by a particle system and thus
-     * influenced by forces. TODO(Sybren): Make this more strict. Probably better to get from the
-     * depsgraph whether this object instance has a time source. */
-    return true;
-  }
-  return BKE_object_moves_in_time(context.object, context.animation_check_include_parent);
-}
-
-}  // namespace USD
diff --git a/source/blender/usd/intern/usd_writer_transform.h b/source/blender/usd/intern/usd_writer_transform.h
deleted file mode 100644
index 52c4a657f33..00000000000
--- a/source/blender/usd/intern/usd_writer_transform.h
+++ /dev/null
@@ -1,42 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-#ifndef __USD_WRITER_TRANSFORM_H__
-#define __USD_WRITER_TRANSFORM_H__
-
-#include "usd_writer_abstract.h"
-
-#include <pxr/usd/usdGeom/xform.h>
-
-namespace USD {
-
-class USDTransformWriter : public USDAbstractWriter {
- private:
-  pxr::UsdGeomXformOp xformOp_;
-
- public:
-  USDTransformWriter(const USDExporterContext &ctx);
-
- protected:
-  void do_write(HierarchyContext &context) override;
-  bool check_is_animated(const HierarchyContext &context) const override;
-};
-
-}  // namespace USD
-
-#endif /* __USD_WRITER_TRANSFORM_H__ */
diff --git a/source/blender/usd/usd.h b/source/blender/usd/usd.h
deleted file mode 100644
index 8a5575d53cf..00000000000
--- a/source/blender/usd/usd.h
+++ /dev/null
@@ -1,63 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2019 Blender Foundation.
- * All rights reserved.
- */
-
-#ifndef __USD_H__
-#define __USD_H__
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#include "DEG_depsgraph.h"
-
-struct Scene;
-struct bContext;
-
-struct USDExportParams {
-  bool export_animation;
-  bool export_hair;
-  bool export_uvmaps;
-  bool export_normals;
-  bool export_materials;
-  bool selected_objects_only;
-  bool use_instancing;
-  enum eEvaluationMode evaluation_mode;
-};
-
-/* The USD_export takes a as_background_job parameter, and returns a boolean.
- *
- * When as_background_job=true, returns false immediately after scheduling
- * a background job.
- *
- * When as_background_job=false, performs the export synchronously, and returns
- * true when the export was ok, and false if there were any errors.
- */
-
-bool USD_export(struct bContext *C,
-                const char *filepath,
-                const struct USDExportParams *params,
-                bool as_background_job);
-
-int USD_get_version(void);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* __USD_H__ */