Cleanup: Alembic, moved exporter code into separate directory

This moves most of the exporter-related code
from `source/blender/io/alembic/intern`
to   `source/blender/io/alembic/exporter`

This is to prepare the Alembic code for the switchover to using
`blender::io::AbstractHierarchyIterator`. When that happens, a few more
files will be added, and having things in a separate 'exporter'
directory makes things less cluttered.

Note that exporting consists of multiple steps (determine export
hierarchy, create Alembic archive, and then write data into it), which
is why the directory is called "exporter", but many of the files are
called "writer".

No functional changes.

1 files changed, 124 insertions, 0 deletions

diff --git a/source/blender/io/alembic/exporter/abc_writer_transform.cc b/source/blender/io/alembic/exporter/abc_writer_transform.cc
new file mode 100644
index 00000000000..46130cb8675
--- /dev/null
+++ b/source/blender/io/alembic/exporter/abc_writer_transform.cc
@@ -0,0 +1,124 @@
+/*
+ * 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.
+ */
+
+/** \file
+ * \ingroup balembic
+ */
+
+#include "abc_writer_transform.h"
+#include "intern/abc_axis_conversion.h"
+
+#include <OpenEXR/ImathBoxAlgo.h>
+
+#include "DNA_object_types.h"
+
+#include "BLI_math.h"
+
+#include "DEG_depsgraph_query.h"
+
+using Alembic::AbcGeom::OObject;
+using Alembic::AbcGeom::OXform;
+
+AbcTransformWriter::AbcTransformWriter(Object *ob,
+                                       const OObject &abc_parent,
+                                       AbcTransformWriter *parent,
+                                       unsigned int time_sampling,
+                                       ExportSettings &settings)
+    : AbcObjectWriter(ob, time_sampling, settings, parent), m_proxy_from(NULL)
+{
+  m_is_animated = hasAnimation(m_object);
+
+  if (!m_is_animated) {
+    time_sampling = 0;
+  }
+
+  m_xform = OXform(abc_parent, get_id_name(m_object), time_sampling);
+  m_schema = m_xform.getSchema();
+
+  /* Blender objects can't have a parent without inheriting the transform. */
+  m_inherits_xform = parent != NULL;
+}
+
+void AbcTransformWriter::do_write()
+{
+  Object *ob_eval = DEG_get_evaluated_object(m_settings.depsgraph, m_object);
+
+  if (m_first_frame) {
+    m_visibility = Alembic::AbcGeom::CreateVisibilityProperty(
+        m_xform, m_xform.getSchema().getTimeSampling());
+  }
+
+  m_visibility.set(!(ob_eval->restrictflag & OB_RESTRICT_VIEWPORT));
+
+  if (!m_first_frame && !m_is_animated) {
+    return;
+  }
+
+  float yup_mat[4][4];
+  create_transform_matrix(
+      ob_eval, yup_mat, m_inherits_xform ? ABC_MATRIX_LOCAL : ABC_MATRIX_WORLD, m_proxy_from);
+
+  /* If the parent is a camera, undo its to-Maya rotation (see below). */
+  bool is_root_object = !m_inherits_xform || ob_eval->parent == nullptr;
+  if (!is_root_object && ob_eval->parent->type == OB_CAMERA) {
+    float rot_mat[4][4];
+    axis_angle_to_mat4_single(rot_mat, 'X', M_PI_2);
+    mul_m4_m4m4(yup_mat, rot_mat, yup_mat);
+  }
+
+  /* If the object is a camera, apply an extra rotation to Maya camera orientation. */
+  if (ob_eval->type == OB_CAMERA) {
+    float rot_mat[4][4];
+    axis_angle_to_mat4_single(rot_mat, 'X', -M_PI_2);
+    mul_m4_m4m4(yup_mat, yup_mat, rot_mat);
+  }
+
+  if (is_root_object) {
+    /* Only apply scaling to root objects, parenting will propagate it. */
+    float scale_mat[4][4];
+    scale_m4_fl(scale_mat, m_settings.global_scale);
+    scale_mat[3][3] = m_settings.global_scale; /* also scale translation */
+    mul_m4_m4m4(yup_mat, yup_mat, scale_mat);
+    yup_mat[3][3] /= m_settings.global_scale; /* normalise the homogeneous component */
+  }
+
+  m_matrix = convert_matrix_datatype(yup_mat);
+  m_sample.setMatrix(m_matrix);
+
+  /* Always export as "inherits transform", as this is the only way in which Blender works. The
+   * above code has already taken care of writing the correct matrix so that this option is not
+   * necessary. However, certain packages (for example the USD Alembic exporter) are incompatible
+   * with non-inheriting transforms and will completely ignore the transform if that is used. */
+  m_sample.setInheritsXforms(true);
+  m_schema.set(m_sample);
+}
+
+Imath::Box3d AbcTransformWriter::bounds()
+{
+  Imath::Box3d bounds;
+
+  for (int i = 0; i < m_children.size(); i++) {
+    Imath::Box3d box(m_children[i]->bounds());
+    bounds.extendBy(box);
+  }
+
+  return Imath::transform(bounds, m_matrix);
+}
+
+bool AbcTransformWriter::hasAnimation(Object * /*ob*/) const
+{
+  return true;
+}