Alembic: new exporter based on the USD exporter structure

The Alembic exporter has been restructured by leverages the
`AbstractHierarchyIterator` introduced by the USD exporter. The produced
Alembic files have not changed much (details below), as the Alembic
writing code has simply been moved from the old exporter to the new. How
the export hierarchy is handled changed a lot, though, and also the way
in which transforms are computed. As a result, T71395 is fixed.

Differences between the old and new exporter, in terms of the produced
Alembic file:
- Duplicated objects now have a unique numerical suffix.
- Matrices are computed differently, namely by simply computing the
  evaluated transform of the object relative to the evaluated transform
  of its export-parent. This fixes {T71395}, but otherwise should
  produce the same result as before (but with simpler code).

Compared to the old Alembic exporter, Subdivision modifiers are now
disabled in a cleaner, more efficient way (they are disabled when
exporting with the "Apply Subdivisions" option is unchecked). Previously
the exporter would move to a new frame, disable the modifier, evaluate
the object, and enable the modifier again. This is now done before
exporting starts, and modifiers are only restored when exporting ends.

Some issues with the old Alembic exporter that have NOT been fixed in
this patch:
- Exporting NURBS patches and curves (see T49114 for example).
- Exporting flattened hierarchy in combination with dupli-objects. This
  seems to be broken in the old Alembic exporter as well, but nobody
  reported this yet.

Differential Revision: https://developer.blender.org/D7664

Reviewed By: Sergey

1 files changed, 0 insertions, 131 deletions

diff --git a/source/blender/io/alembic/exporter/abc_exporter.h b/source/blender/io/alembic/exporter/abc_exporter.h
deleted file mode 100644
index af30f2ceb50..00000000000
--- a/source/blender/io/alembic/exporter/abc_exporter.h
+++ /dev/null
@@ -1,131 +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.
- */
-#pragma once
-
-/** \file
- * \ingroup balembic
- */
-
-#include <Alembic/Abc/All.h>
-#include <map>
-#include <set>
-#include <vector>
-
-#include "intern/abc_util.h"
-
-struct Base;
-struct Depsgraph;
-struct Main;
-struct Object;
-struct Scene;
-struct ViewLayer;
-
-namespace blender {
-namespace io {
-namespace alembic {
-
-class AbcObjectWriter;
-class AbcTransformWriter;
-class ArchiveWriter;
-
-struct ExportSettings {
-  ExportSettings();
-
-  Scene *scene;
-  /** Scene layer to export; all its objects will be exported, unless selected_only=true. */
-  ViewLayer *view_layer;
-  Depsgraph *depsgraph;
-  SimpleLogger logger;
-
-  bool selected_only;
-  bool visible_objects_only;
-  bool renderable_only;
-
-  double frame_start, frame_end;
-  double frame_samples_xform;
-  double frame_samples_shape;
-  double shutter_open;
-  double shutter_close;
-  float global_scale;
-
-  bool flatten_hierarchy;
-
-  bool export_normals;
-  bool export_uvs;
-  bool export_vcols;
-  bool export_face_sets;
-  bool export_vweigths;
-  bool export_hair;
-  bool export_particles;
-
-  bool apply_subdiv;
-  bool curves_as_mesh;
-  bool use_subdiv_schema;
-  bool export_child_hairs;
-  bool pack_uv;
-  bool triangulate;
-
-  int quad_method;
-  int ngon_method;
-};
-
-class AbcExporter {
-  Main *m_bmain;
-  ExportSettings &m_settings;
-
-  const char *m_filename;
-
-  unsigned int m_trans_sampling_index, m_shape_sampling_index;
-
-  ArchiveWriter *m_writer;
-
-  /* mapping from name to transform writer */
-  typedef std::map<std::string, AbcTransformWriter *> m_xforms_type;
-  m_xforms_type m_xforms;
-
-  std::vector<AbcObjectWriter *> m_shapes;
-
- public:
-  AbcExporter(Main *bmain, const char *filename, ExportSettings &settings);
-  ~AbcExporter();
-
-  void operator()(short *do_update, float *progress, bool *was_canceled);
-
- protected:
-  void getShutterSamples(unsigned int nr_of_samples,
-                         bool time_relative,
-                         std::vector<double> &samples);
-  void getFrameSet(unsigned int nr_of_samples, std::set<double> &frames);
-
- private:
-  Alembic::Abc::TimeSamplingPtr createTimeSampling(double step);
-
-  void createTransformWritersHierarchy();
-  AbcTransformWriter *createTransformWriter(Object *ob, Object *parent, Object *dupliObParent);
-  void exploreTransform(Base *base, Object *object, Object *parent, Object *dupliObParent);
-  void exploreObject(Base *base, Object *object, Object *dupliObParent);
-  void createShapeWriters();
-  void createShapeWriter(Object *ob, Object *dupliObParent);
-  void createParticleSystemsWriters(Object *ob, AbcTransformWriter *xform);
-
-  AbcTransformWriter *getXForm(const std::string &name);
-
-  void setCurrentFrame(Main *bmain, double t);
-};
-
-}  // namespace alembic
-}  // namespace io
-}  // namespace blender