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-rw-r--r--source/blender/editors/io/io_usd.c17
-rw-r--r--source/blender/io/alembic/exporter/abc_export_capi.cc2
-rw-r--r--source/blender/io/alembic/exporter/abc_hierarchy_iterator.cc5
-rw-r--r--source/blender/io/alembic/exporter/abc_hierarchy_iterator.h4
-rw-r--r--source/blender/io/common/IO_abstract_hierarchy_iterator.h4
-rw-r--r--source/blender/io/common/intern/abstract_hierarchy_iterator.cc4
-rw-r--r--source/blender/io/common/intern/abstract_hierarchy_iterator_test.cc5
-rw-r--r--source/blender/io/usd/CMakeLists.txt13
-rw-r--r--source/blender/io/usd/intern/usd_capi_export.cc2
-rw-r--r--source/blender/io/usd/intern/usd_exporter_context.h2
-rw-r--r--source/blender/io/usd/intern/usd_hierarchy_iterator.cc21
-rw-r--r--source/blender/io/usd/intern/usd_hierarchy_iterator.h5
-rw-r--r--source/blender/io/usd/intern/usd_writer_abstract.cc5
-rw-r--r--source/blender/io/usd/intern/usd_writer_abstract.h1
-rw-r--r--source/blender/io/usd/intern/usd_writer_material.cc10
-rw-r--r--source/blender/io/usd/intern/usd_writer_volume.cc188
-rw-r--r--source/blender/io/usd/intern/usd_writer_volume.h36
-rw-r--r--source/blender/io/usd/usd.h2
18 files changed, 294 insertions, 32 deletions
diff --git a/source/blender/editors/io/io_usd.c b/source/blender/editors/io/io_usd.c
index e0616a0cec3..97ca9b026ec 100644
--- a/source/blender/editors/io/io_usd.c
+++ b/source/blender/editors/io/io_usd.c
@@ -118,7 +118,7 @@ static int wm_usd_export_exec(bContext *C, wmOperator *op)
const bool generate_preview_surface = RNA_boolean_get(op->ptr, "generate_preview_surface");
const bool export_textures = RNA_boolean_get(op->ptr, "export_textures");
const bool overwrite_textures = RNA_boolean_get(op->ptr, "overwrite_textures");
- const bool relative_texture_paths = RNA_boolean_get(op->ptr, "relative_texture_paths");
+ const bool relative_paths = RNA_boolean_get(op->ptr, "relative_paths");
struct USDExportParams params = {
export_animation,
@@ -133,7 +133,7 @@ static int wm_usd_export_exec(bContext *C, wmOperator *op)
generate_preview_surface,
export_textures,
overwrite_textures,
- relative_texture_paths,
+ relative_paths,
};
bool ok = USD_export(C, filename, &params, as_background_job);
@@ -181,9 +181,9 @@ static void wm_usd_export_draw(bContext *UNUSED(C), wmOperator *op)
const bool export_tex = RNA_boolean_get(ptr, "export_textures");
uiLayoutSetActive(row, export_mtl && preview && export_tex);
- row = uiLayoutRow(col, true);
- uiItemR(row, ptr, "relative_texture_paths", 0, NULL, ICON_NONE);
- uiLayoutSetActive(row, export_mtl && preview);
+ box = uiLayoutBox(layout);
+ col = uiLayoutColumnWithHeading(box, true, IFACE_("File References"));
+ uiItemR(col, ptr, "relative_paths", 0, NULL, ICON_NONE);
box = uiLayoutBox(layout);
uiItemL(box, IFACE_("Experimental"), ICON_NONE);
@@ -282,10 +282,11 @@ void WM_OT_usd_export(struct wmOperatorType *ot)
"Allow overwriting existing texture files when exporting textures");
RNA_def_boolean(ot->srna,
- "relative_texture_paths",
+ "relative_paths",
true,
- "Relative Texture Paths",
- "Make texture asset paths relative to the USD file");
+ "Relative Paths",
+ "Use relative paths to reference external files (i.e. textures, volumes) in "
+ "USD, otherwise use absolute paths");
}
/* ====== USD Import ====== */
diff --git a/source/blender/io/alembic/exporter/abc_export_capi.cc b/source/blender/io/alembic/exporter/abc_export_capi.cc
index c1ff7df0c37..edaf53b3efa 100644
--- a/source/blender/io/alembic/exporter/abc_export_capi.cc
+++ b/source/blender/io/alembic/exporter/abc_export_capi.cc
@@ -115,7 +115,7 @@ static void export_startjob(void *customdata,
return;
}
- ABCHierarchyIterator iter(data->depsgraph, abc_archive.get(), data->params);
+ ABCHierarchyIterator iter(data->bmain, data->depsgraph, abc_archive.get(), data->params);
if (export_animation) {
CLOG_INFO(&LOG, 2, "Exporting animation");
diff --git a/source/blender/io/alembic/exporter/abc_hierarchy_iterator.cc b/source/blender/io/alembic/exporter/abc_hierarchy_iterator.cc
index d33adfdb4b9..ab62694b802 100644
--- a/source/blender/io/alembic/exporter/abc_hierarchy_iterator.cc
+++ b/source/blender/io/alembic/exporter/abc_hierarchy_iterator.cc
@@ -26,10 +26,11 @@
namespace blender::io::alembic {
-ABCHierarchyIterator::ABCHierarchyIterator(Depsgraph *depsgraph,
+ABCHierarchyIterator::ABCHierarchyIterator(Main *bmain,
+ Depsgraph *depsgraph,
ABCArchive *abc_archive,
const AlembicExportParams &params)
- : AbstractHierarchyIterator(depsgraph), abc_archive_(abc_archive), params_(params)
+ : AbstractHierarchyIterator(bmain, depsgraph), abc_archive_(abc_archive), params_(params)
{
}
diff --git a/source/blender/io/alembic/exporter/abc_hierarchy_iterator.h b/source/blender/io/alembic/exporter/abc_hierarchy_iterator.h
index 24d3f319fbd..f7814c28a55 100644
--- a/source/blender/io/alembic/exporter/abc_hierarchy_iterator.h
+++ b/source/blender/io/alembic/exporter/abc_hierarchy_iterator.h
@@ -13,6 +13,7 @@
#include <Alembic/Abc/OObject.h>
struct Depsgraph;
+struct Main;
struct Object;
namespace blender::io::alembic {
@@ -36,7 +37,8 @@ class ABCHierarchyIterator : public AbstractHierarchyIterator {
const AlembicExportParams &params_;
public:
- ABCHierarchyIterator(Depsgraph *depsgraph,
+ ABCHierarchyIterator(Main *bmain,
+ Depsgraph *depsgraph,
ABCArchive *abc_archive_,
const AlembicExportParams &params);
diff --git a/source/blender/io/common/IO_abstract_hierarchy_iterator.h b/source/blender/io/common/IO_abstract_hierarchy_iterator.h
index 3c6b6cc631e..3371501db95 100644
--- a/source/blender/io/common/IO_abstract_hierarchy_iterator.h
+++ b/source/blender/io/common/IO_abstract_hierarchy_iterator.h
@@ -30,6 +30,7 @@
struct Depsgraph;
struct DupliObject;
struct ID;
+struct Main;
struct Object;
struct ParticleSystem;
@@ -204,12 +205,13 @@ class AbstractHierarchyIterator {
protected:
ExportGraph export_graph_;
ExportPathMap duplisource_export_path_;
+ Main *bmain_;
Depsgraph *depsgraph_;
WriterMap writers_;
ExportSubset export_subset_;
public:
- explicit AbstractHierarchyIterator(Depsgraph *depsgraph);
+ explicit AbstractHierarchyIterator(Main *bmain, Depsgraph *depsgraph);
virtual ~AbstractHierarchyIterator();
/* Iterate over the depsgraph, create writers, and tell the writers to write.
diff --git a/source/blender/io/common/intern/abstract_hierarchy_iterator.cc b/source/blender/io/common/intern/abstract_hierarchy_iterator.cc
index f0501d4cf62..82bb1c57833 100644
--- a/source/blender/io/common/intern/abstract_hierarchy_iterator.cc
+++ b/source/blender/io/common/intern/abstract_hierarchy_iterator.cc
@@ -161,8 +161,8 @@ bool AbstractHierarchyWriter::check_has_deforming_physics(const HierarchyContext
return rbo != nullptr && rbo->type == RBO_TYPE_ACTIVE && (rbo->flag & RBO_FLAG_USE_DEFORM) != 0;
}
-AbstractHierarchyIterator::AbstractHierarchyIterator(Depsgraph *depsgraph)
- : depsgraph_(depsgraph), export_subset_({true, true})
+AbstractHierarchyIterator::AbstractHierarchyIterator(Main *bmain, Depsgraph *depsgraph)
+ : bmain_(bmain), depsgraph_(depsgraph), export_subset_({true, true})
{
}
diff --git a/source/blender/io/common/intern/abstract_hierarchy_iterator_test.cc b/source/blender/io/common/intern/abstract_hierarchy_iterator_test.cc
index 52cae89c2e8..81a3546259e 100644
--- a/source/blender/io/common/intern/abstract_hierarchy_iterator_test.cc
+++ b/source/blender/io/common/intern/abstract_hierarchy_iterator_test.cc
@@ -54,7 +54,8 @@ class TestingHierarchyIterator : public AbstractHierarchyIterator {
used_writers hair_writers;
used_writers particle_writers;
- explicit TestingHierarchyIterator(Depsgraph *depsgraph) : AbstractHierarchyIterator(depsgraph)
+ explicit TestingHierarchyIterator(Main *bmain, Depsgraph *depsgraph)
+ : AbstractHierarchyIterator(bmain, depsgraph)
{
}
~TestingHierarchyIterator() override
@@ -105,7 +106,7 @@ class AbstractHierarchyIteratorTest : public BlendfileLoadingBaseTest {
/* Create a test iterator. */
void iterator_create()
{
- iterator = new TestingHierarchyIterator(depsgraph);
+ iterator = new TestingHierarchyIterator(bfile->main, depsgraph);
}
/* Free the test iterator if it is not nullptr. */
void iterator_free()
diff --git a/source/blender/io/usd/CMakeLists.txt b/source/blender/io/usd/CMakeLists.txt
index e2e959814fa..7a7c95b29f9 100644
--- a/source/blender/io/usd/CMakeLists.txt
+++ b/source/blender/io/usd/CMakeLists.txt
@@ -69,6 +69,7 @@ set(SRC
intern/usd_writer_mesh.cc
intern/usd_writer_metaball.cc
intern/usd_writer_transform.cc
+ intern/usd_writer_volume.cc
intern/usd_reader_camera.cc
intern/usd_reader_curve.cc
@@ -95,6 +96,7 @@ set(SRC
intern/usd_writer_mesh.h
intern/usd_writer_metaball.h
intern/usd_writer_transform.h
+ intern/usd_writer_volume.h
intern/usd_reader_camera.h
intern/usd_reader_curve.h
@@ -119,8 +121,15 @@ list(APPEND LIB
${BOOST_LIBRARIES}
)
-list(APPEND LIB
-)
+if(WITH_OPENVDB)
+ add_definitions(-DWITH_OPENVDB ${OPENVDB_DEFINITIONS})
+ list(APPEND INC_SYS
+ ${OPENVDB_INCLUDE_DIRS}
+ )
+ list(APPEND LIB
+ ${OPENVDB_LIBRARIES}
+ )
+endif()
blender_add_lib(bf_usd "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")
diff --git a/source/blender/io/usd/intern/usd_capi_export.cc b/source/blender/io/usd/intern/usd_capi_export.cc
index d7c1a5adc7c..c52d791f3b3 100644
--- a/source/blender/io/usd/intern/usd_capi_export.cc
+++ b/source/blender/io/usd/intern/usd_capi_export.cc
@@ -97,7 +97,7 @@ static void export_startjob(void *customdata,
usd_stage->SetEndTimeCode(scene->r.efra);
}
- USDHierarchyIterator iter(data->depsgraph, usd_stage, data->params);
+ USDHierarchyIterator iter(data->bmain, 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. */
diff --git a/source/blender/io/usd/intern/usd_exporter_context.h b/source/blender/io/usd/intern/usd_exporter_context.h
index 5a3f94d01f8..a636d849296 100644
--- a/source/blender/io/usd/intern/usd_exporter_context.h
+++ b/source/blender/io/usd/intern/usd_exporter_context.h
@@ -8,12 +8,14 @@
#include <pxr/usd/usd/common.h>
struct Depsgraph;
+struct Main;
namespace blender::io::usd {
class USDHierarchyIterator;
struct USDExporterContext {
+ Main *bmain;
Depsgraph *depsgraph;
const pxr::UsdStageRefPtr stage;
const pxr::SdfPath usd_path;
diff --git a/source/blender/io/usd/intern/usd_hierarchy_iterator.cc b/source/blender/io/usd/intern/usd_hierarchy_iterator.cc
index 7a0d896fb3e..51261c4d91e 100644
--- a/source/blender/io/usd/intern/usd_hierarchy_iterator.cc
+++ b/source/blender/io/usd/intern/usd_hierarchy_iterator.cc
@@ -10,6 +10,7 @@
#include "usd_writer_mesh.h"
#include "usd_writer_metaball.h"
#include "usd_writer_transform.h"
+#include "usd_writer_volume.h"
#include <string>
@@ -28,10 +29,11 @@
namespace blender::io::usd {
-USDHierarchyIterator::USDHierarchyIterator(Depsgraph *depsgraph,
+USDHierarchyIterator::USDHierarchyIterator(Main *bmain,
+ Depsgraph *depsgraph,
pxr::UsdStageRefPtr stage,
const USDExportParams &params)
- : AbstractHierarchyIterator(depsgraph), stage_(stage), params_(params)
+ : AbstractHierarchyIterator(bmain, depsgraph), stage_(stage), params_(params)
{
}
@@ -59,6 +61,15 @@ void USDHierarchyIterator::set_export_frame(float frame_nr)
export_time_ = pxr::UsdTimeCode(frame_nr);
}
+std::string USDHierarchyIterator::get_export_file_path() const
+{
+ /* Returns the same path that was passed to `stage_` object during it's creation (via
+ * `pxr::UsdStage::CreateNew` function). */
+ const pxr::SdfLayerHandle root_layer = stage_->GetRootLayer();
+ const std::string usd_export_file_path = root_layer->GetRealPath();
+ return usd_export_file_path;
+}
+
const pxr::UsdTimeCode &USDHierarchyIterator::get_export_time_code() const
{
return export_time_;
@@ -66,7 +77,8 @@ const pxr::UsdTimeCode &USDHierarchyIterator::get_export_time_code() const
USDExporterContext USDHierarchyIterator::create_usd_export_context(const HierarchyContext *context)
{
- return USDExporterContext{depsgraph_, stage_, pxr::SdfPath(context->export_path), this, params_};
+ return USDExporterContext{
+ bmain_, depsgraph_, stage_, pxr::SdfPath(context->export_path), this, params_};
}
AbstractHierarchyWriter *USDHierarchyIterator::create_transform_writer(
@@ -93,6 +105,9 @@ AbstractHierarchyWriter *USDHierarchyIterator::create_data_writer(const Hierarch
case OB_MBALL:
data_writer = new USDMetaballWriter(usd_export_context);
break;
+ case OB_VOLUME:
+ data_writer = new USDVolumeWriter(usd_export_context);
+ break;
case OB_EMPTY:
case OB_CURVES_LEGACY:
diff --git a/source/blender/io/usd/intern/usd_hierarchy_iterator.h b/source/blender/io/usd/intern/usd_hierarchy_iterator.h
index d5566103af4..445c37238be 100644
--- a/source/blender/io/usd/intern/usd_hierarchy_iterator.h
+++ b/source/blender/io/usd/intern/usd_hierarchy_iterator.h
@@ -12,6 +12,7 @@
#include <pxr/usd/usd/timeCode.h>
struct Depsgraph;
+struct Main;
struct Object;
namespace blender::io::usd {
@@ -27,11 +28,13 @@ class USDHierarchyIterator : public AbstractHierarchyIterator {
const USDExportParams &params_;
public:
- USDHierarchyIterator(Depsgraph *depsgraph,
+ USDHierarchyIterator(Main *bmain,
+ Depsgraph *depsgraph,
pxr::UsdStageRefPtr stage,
const USDExportParams &params);
void set_export_frame(float frame_nr);
+ std::string get_export_file_path() const;
const pxr::UsdTimeCode &get_export_time_code() const;
virtual std::string make_valid_name(const std::string &name) const override;
diff --git a/source/blender/io/usd/intern/usd_writer_abstract.cc b/source/blender/io/usd/intern/usd_writer_abstract.cc
index dbeb9df1ee8..2be9b1c065a 100644
--- a/source/blender/io/usd/intern/usd_writer_abstract.cc
+++ b/source/blender/io/usd/intern/usd_writer_abstract.cc
@@ -47,6 +47,11 @@ bool USDAbstractWriter::is_supported(const HierarchyContext * /*context*/) const
return true;
}
+std::string USDAbstractWriter::get_export_file_path() const
+{
+ return usd_export_context_.hierarchy_iterator->get_export_file_path();
+}
+
pxr::UsdTimeCode USDAbstractWriter::get_export_time_code() const
{
if (is_animated_) {
diff --git a/source/blender/io/usd/intern/usd_writer_abstract.h b/source/blender/io/usd/intern/usd_writer_abstract.h
index 66feb6e1070..8adc054c2c2 100644
--- a/source/blender/io/usd/intern/usd_writer_abstract.h
+++ b/source/blender/io/usd/intern/usd_writer_abstract.h
@@ -51,6 +51,7 @@ class USDAbstractWriter : public AbstractHierarchyWriter {
protected:
virtual void do_write(HierarchyContext &context) = 0;
+ std::string get_export_file_path() const;
pxr::UsdTimeCode get_export_time_code() const;
pxr::UsdShadeMaterial ensure_usd_material(const HierarchyContext &context, Material *material);
diff --git a/source/blender/io/usd/intern/usd_writer_material.cc b/source/blender/io/usd/intern/usd_writer_material.cc
index 1bfc0e50f69..a24877a20bd 100644
--- a/source/blender/io/usd/intern/usd_writer_material.cc
+++ b/source/blender/io/usd/intern/usd_writer_material.cc
@@ -576,7 +576,7 @@ static std::string get_tex_image_asset_path(bNode *node,
char file_path[FILE_MAX];
BLI_split_file_part(path.c_str(), file_path, FILE_MAX);
- if (export_params.relative_texture_paths) {
+ if (export_params.relative_paths) {
BLI_path_join(exp_path, FILE_MAX, ".", "textures", file_path, nullptr);
}
else {
@@ -594,7 +594,7 @@ static std::string get_tex_image_asset_path(bNode *node,
return exp_path;
}
- if (export_params.relative_texture_paths) {
+ if (export_params.relative_paths) {
/* Get the path relative to the USD. */
pxr::SdfLayerHandle layer = stage->GetRootLayer();
std::string stage_path = layer->GetRealPath();
@@ -606,11 +606,7 @@ static std::string get_tex_image_asset_path(bNode *node,
strcpy(rel_path, path.c_str());
BLI_path_rel(rel_path, stage_path.c_str());
-
- /* BLI_path_rel adds '//' as a prefix to the path, if
- * generating the relative path was successful. */
- if (rel_path[0] != '/' || rel_path[1] != '/') {
- /* No relative path generated. */
+ if (!BLI_path_is_rel(rel_path)) {
return path;
}
diff --git a/source/blender/io/usd/intern/usd_writer_volume.cc b/source/blender/io/usd/intern/usd_writer_volume.cc
new file mode 100644
index 00000000000..b83ded1e5d0
--- /dev/null
+++ b/source/blender/io/usd/intern/usd_writer_volume.cc
@@ -0,0 +1,188 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "usd_writer_volume.h"
+
+#include <pxr/base/tf/pathUtils.h>
+#include <pxr/usd/usdVol/openVDBAsset.h>
+#include <pxr/usd/usdVol/volume.h>
+
+#include "DNA_volume_types.h"
+#include "DNA_windowmanager_types.h"
+
+#include "BKE_volume.h"
+
+#include "BLI_fileops.h"
+#include "BLI_index_range.hh"
+#include "BLI_path_util.h"
+#include "BLI_string.h"
+
+#include "WM_api.h"
+
+#include "usd_hierarchy_iterator.h"
+
+namespace blender::io::usd {
+
+USDVolumeWriter::USDVolumeWriter(const USDExporterContext &ctx) : USDAbstractWriter(ctx)
+{
+}
+
+bool USDVolumeWriter::check_is_animated(const HierarchyContext &context) const
+{
+ const Volume *volume = static_cast<Volume *>(context.object->data);
+ return volume->is_sequence;
+}
+
+void USDVolumeWriter::do_write(HierarchyContext &context)
+{
+ Volume *volume = static_cast<Volume *>(context.object->data);
+ if (!BKE_volume_load(volume, usd_export_context_.bmain)) {
+ return;
+ }
+
+ const int num_grids = BKE_volume_num_grids(volume);
+ if (!num_grids) {
+ return;
+ }
+
+ auto vdb_file_path = resolve_vdb_file(volume);
+ if (!vdb_file_path.has_value()) {
+ WM_reportf(RPT_WARNING,
+ "USD Export: failed to resolve .vdb file for object: %s",
+ volume->id.name + 2);
+ return;
+ }
+
+ if (usd_export_context_.export_params.relative_paths) {
+ if (auto relative_vdb_file_path = construct_vdb_relative_file_path(vdb_file_path.value())) {
+ vdb_file_path = relative_vdb_file_path;
+ }
+ else {
+ WM_reportf(RPT_WARNING,
+ "USD Export: couldn't construct relative file path for .vdb file, absolute path "
+ "will be used instead");
+ }
+ }
+
+ const pxr::UsdTimeCode timecode = get_export_time_code();
+ const pxr::SdfPath &volume_path = usd_export_context_.usd_path;
+ pxr::UsdStageRefPtr stage = usd_export_context_.stage;
+ pxr::UsdVolVolume usd_volume = pxr::UsdVolVolume::Define(stage, volume_path);
+
+ for (const int i : IndexRange(num_grids)) {
+ const VolumeGrid *grid = BKE_volume_grid_get_for_read(volume, i);
+ const std::string grid_name = BKE_volume_grid_name(grid);
+ const std::string grid_id = pxr::TfMakeValidIdentifier(grid_name);
+ const pxr::SdfPath grid_path = volume_path.AppendPath(pxr::SdfPath(grid_id));
+ pxr::UsdVolOpenVDBAsset usd_grid = pxr::UsdVolOpenVDBAsset::Define(stage, grid_path);
+ usd_grid.GetFieldNameAttr().Set(pxr::TfToken(grid_name), timecode);
+ usd_grid.GetFilePathAttr().Set(pxr::SdfAssetPath(vdb_file_path.value()), timecode);
+ usd_volume.CreateFieldRelationship(pxr::TfToken(grid_id), grid_path);
+ }
+
+ float3 volume_bound_min(std::numeric_limits<float>::max());
+ float3 volume_bound_max(std::numeric_limits<float>::min());
+ if (BKE_volume_min_max(volume, volume_bound_min, volume_bound_max)) {
+ const pxr::VtArray<pxr::GfVec3f> volume_extent = {pxr::GfVec3f(&volume_bound_min[0]),
+ pxr::GfVec3f(&volume_bound_max[0])};
+ usd_volume.GetExtentAttr().Set(volume_extent, timecode);
+ }
+
+ BKE_volume_unload(volume);
+}
+
+std::optional<std::string> USDVolumeWriter::resolve_vdb_file(const Volume *volume) const
+{
+ std::optional<std::string> vdb_file_path;
+ if (volume->filepath[0] == '\0') {
+ /* Entering this section should mean that Volume object contains OpenVDB data that is not
+ * obtained from external .vdb file but rather generated inside of Blender (i.e. by 'Mesh to
+ * Volume' modifier). Try to save this data to a .vdb file. */
+
+ vdb_file_path = construct_vdb_file_path(volume);
+ if (!BKE_volume_save(
+ volume, usd_export_context_.bmain, NULL, vdb_file_path.value_or("").c_str())) {
+ return std::nullopt;
+ }
+ }
+
+ if (!vdb_file_path.has_value()) {
+ vdb_file_path = BKE_volume_grids_frame_filepath(volume);
+ if (vdb_file_path.value().empty()) {
+ return std::nullopt;
+ }
+ }
+
+ return vdb_file_path;
+}
+
+std::optional<std::string> USDVolumeWriter::construct_vdb_file_path(const Volume *volume) const
+{
+ const std::string usd_file_path = get_export_file_path();
+ if (usd_file_path.empty()) {
+ return std::nullopt;
+ }
+
+ char usd_directory_path[FILE_MAX];
+ char usd_file_name[FILE_MAXFILE];
+ BLI_split_dirfile(usd_file_path.c_str(),
+ usd_directory_path,
+ usd_file_name,
+ sizeof(usd_directory_path),
+ sizeof(usd_file_name));
+
+ if (usd_directory_path[0] == '\0' || usd_file_name[0] == '\0') {
+ return std::nullopt;
+ }
+
+ const char *vdb_directory_name = "volumes";
+
+ char vdb_directory_path[FILE_MAX];
+ BLI_strncpy(vdb_directory_path, usd_directory_path, FILE_MAX);
+ strcat(vdb_directory_path, vdb_directory_name);
+ BLI_dir_create_recursive(vdb_directory_path);
+
+ char vdb_file_name[FILE_MAXFILE];
+ BLI_strncpy(vdb_file_name, volume->id.name + 2, FILE_MAXFILE);
+ const pxr::UsdTimeCode timecode = get_export_time_code();
+ if (!timecode.IsDefault()) {
+ const int frame = (int)timecode.GetValue();
+ const int num_frame_digits = frame == 0 ? 1 : integer_digits_i(abs(frame));
+ BLI_path_frame(vdb_file_name, frame, num_frame_digits);
+ }
+ strcat(vdb_file_name, ".vdb");
+
+ char vdb_file_path[FILE_MAX];
+ BLI_path_join(vdb_file_path, sizeof(vdb_file_path), vdb_directory_path, vdb_file_name, NULL);
+
+ return vdb_file_path;
+}
+
+std::optional<std::string> USDVolumeWriter::construct_vdb_relative_file_path(
+ const std::string &vdb_file_path) const
+{
+ const std::string usd_file_path = get_export_file_path();
+ if (usd_file_path.empty()) {
+ return std::nullopt;
+ }
+
+ char relative_path[FILE_MAX];
+ BLI_strncpy(relative_path, vdb_file_path.c_str(), FILE_MAX);
+ BLI_path_rel(relative_path, usd_file_path.c_str());
+ if (!BLI_path_is_rel(relative_path)) {
+ return std::nullopt;
+ }
+
+ /* Following code was written with an assumption that Blender's relative paths start with
+ * // characters as well as have OS dependent slashes. Inside of USD files those relative
+ * paths should start with either ./ or ../ characters and have always forward slashes (/)
+ * separating directories. This is the convention used in USD documentation (and it seems
+ * to be used in other DCC packages as well). */
+ std::string relative_path_processed = pxr::TfNormPath(relative_path + 2);
+ if (relative_path_processed[0] != '.') {
+ relative_path_processed.insert(0, "./");
+ }
+
+ return relative_path_processed;
+}
+
+} // namespace blender::io::usd
diff --git a/source/blender/io/usd/intern/usd_writer_volume.h b/source/blender/io/usd/intern/usd_writer_volume.h
new file mode 100644
index 00000000000..8c1e36b7e53
--- /dev/null
+++ b/source/blender/io/usd/intern/usd_writer_volume.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#pragma once
+
+#include <optional>
+
+#include "BLI_math_vec_types.hh"
+#include "usd_writer_abstract.h"
+
+struct Volume;
+
+namespace blender::io::usd {
+
+/* Writer for writing OpenVDB assets to UsdVolVolume. Volume data is stored in separate .vdb files
+ * which are referenced in USD file. */
+class USDVolumeWriter : public USDAbstractWriter {
+ public:
+ USDVolumeWriter(const USDExporterContext &ctx);
+
+ protected:
+ virtual bool check_is_animated(const HierarchyContext &context) const override;
+ virtual void do_write(HierarchyContext &context) override;
+
+ private:
+ /* Try to ensure that external .vdb file is available for USD to be referenced. Blender can
+ * either reference external OpenVDB data or generate such data internally. Latter option will
+ * mean that `resolve_vdb_file` method will try to export volume data to a new .vdb file. If
+ * successful, this method returns absolute file path to the resolved .vdb file, if not, returns
+ * `std::nullopt`. */
+ std::optional<std::string> resolve_vdb_file(const Volume *volume) const;
+
+ std::optional<std::string> construct_vdb_file_path(const Volume *volume) const;
+ std::optional<std::string> construct_vdb_relative_file_path(
+ const std::string &vdb_file_path) const;
+};
+
+} // namespace blender::io::usd
diff --git a/source/blender/io/usd/usd.h b/source/blender/io/usd/usd.h
index e63cd0a4e04..deaa27a5252 100644
--- a/source/blender/io/usd/usd.h
+++ b/source/blender/io/usd/usd.h
@@ -28,7 +28,7 @@ struct USDExportParams {
bool generate_preview_surface;
bool export_textures;
bool overwrite_textures;
- bool relative_texture_paths;
+ bool relative_paths;
};
struct USDImportParams {