Cleanup: Alembic, moved axis conversion functions into their own files

The long-term goal is to move code out of `abc_util.{h,cc}` into either
files with better, more concrete names, or simply into the one file
where they are used.

No functional changes.

1 files changed, 166 insertions, 0 deletions

diff --git a/source/blender/io/alembic/intern/abc_axis_conversion.cc b/source/blender/io/alembic/intern/abc_axis_conversion.cc
new file mode 100644
index 00000000000..17db5e9c99f
--- /dev/null
+++ b/source/blender/io/alembic/intern/abc_axis_conversion.cc
@@ -0,0 +1,166 @@
+/*
+ * 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 Alembic
+ */
+
+#include "abc_axis_conversion.h"
+
+extern "C" {
+#include "BLI_assert.h"
+#include "DNA_object_types.h"
+
+#include "BLI_math_geom.h"
+}
+
+void create_swapped_rotation_matrix(float rot_x_mat[3][3],
+                                    float rot_y_mat[3][3],
+                                    float rot_z_mat[3][3],
+                                    const float euler[3],
+                                    AbcAxisSwapMode mode)
+{
+  const float rx = euler[0];
+  float ry;
+  float rz;
+
+  /* Apply transformation */
+  switch (mode) {
+    case ABC_ZUP_FROM_YUP:
+      ry = -euler[2];
+      rz = euler[1];
+      break;
+    case ABC_YUP_FROM_ZUP:
+      ry = euler[2];
+      rz = -euler[1];
+      break;
+    default:
+      ry = 0.0f;
+      rz = 0.0f;
+      BLI_assert(false);
+      break;
+  }
+
+  unit_m3(rot_x_mat);
+  unit_m3(rot_y_mat);
+  unit_m3(rot_z_mat);
+
+  rot_x_mat[1][1] = cos(rx);
+  rot_x_mat[2][1] = -sin(rx);
+  rot_x_mat[1][2] = sin(rx);
+  rot_x_mat[2][2] = cos(rx);
+
+  rot_y_mat[2][2] = cos(ry);
+  rot_y_mat[0][2] = -sin(ry);
+  rot_y_mat[2][0] = sin(ry);
+  rot_y_mat[0][0] = cos(ry);
+
+  rot_z_mat[0][0] = cos(rz);
+  rot_z_mat[1][0] = -sin(rz);
+  rot_z_mat[0][1] = sin(rz);
+  rot_z_mat[1][1] = cos(rz);
+}
+
+/* Convert matrix from Z=up to Y=up or vice versa.
+ * Use yup_mat = zup_mat for in-place conversion. */
+void copy_m44_axis_swap(float dst_mat[4][4], float src_mat[4][4], AbcAxisSwapMode mode)
+{
+  float dst_rot[3][3], src_rot[3][3], dst_scale_mat[4][4];
+  float rot_x_mat[3][3], rot_y_mat[3][3], rot_z_mat[3][3];
+  float src_trans[3], dst_scale[3], src_scale[3], euler[3];
+
+  zero_v3(src_trans);
+  zero_v3(dst_scale);
+  zero_v3(src_scale);
+  zero_v3(euler);
+  unit_m3(src_rot);
+  unit_m3(dst_rot);
+  unit_m4(dst_scale_mat);
+
+  /* TODO(Sybren): This code assumes there is no sheer component and no
+   * homogeneous scaling component, which is not always true when writing
+   * non-hierarchical (e.g. flat) objects (e.g. when parent has non-uniform
+   * scale and the child rotates). This is currently not taken into account
+   * when axis-swapping. */
+
+  /* Extract translation, rotation, and scale form matrix. */
+  mat4_to_loc_rot_size(src_trans, src_rot, src_scale, src_mat);
+
+  /* Get euler angles from rotation matrix. */
+  mat3_to_eulO(euler, ROT_MODE_XZY, src_rot);
+
+  /* Create X, Y, Z rotation matrices from euler angles. */
+  create_swapped_rotation_matrix(rot_x_mat, rot_y_mat, rot_z_mat, euler, mode);
+
+  /* Concatenate rotation matrices. */
+  mul_m3_m3m3(dst_rot, dst_rot, rot_z_mat);
+  mul_m3_m3m3(dst_rot, dst_rot, rot_y_mat);
+  mul_m3_m3m3(dst_rot, dst_rot, rot_x_mat);
+
+  mat3_to_eulO(euler, ROT_MODE_XZY, dst_rot);
+
+  /* Start construction of dst_mat from rotation matrix */
+  unit_m4(dst_mat);
+  copy_m4_m3(dst_mat, dst_rot);
+
+  /* Apply translation */
+  switch (mode) {
+    case ABC_ZUP_FROM_YUP:
+      copy_zup_from_yup(dst_mat[3], src_trans);
+      break;
+    case ABC_YUP_FROM_ZUP:
+      copy_yup_from_zup(dst_mat[3], src_trans);
+      break;
+    default:
+      BLI_assert(false);
+  }
+
+  /* Apply scale matrix. Swaps y and z, but does not
+   * negate like translation does. */
+  dst_scale[0] = src_scale[0];
+  dst_scale[1] = src_scale[2];
+  dst_scale[2] = src_scale[1];
+
+  size_to_mat4(dst_scale_mat, dst_scale);
+  mul_m4_m4m4(dst_mat, dst_mat, dst_scale_mat);
+}
+
+/* Recompute transform matrix of object in new coordinate system
+ * (from Z-Up to Y-Up). */
+void create_transform_matrix(Object *obj,
+                             float r_yup_mat[4][4],
+                             AbcMatrixMode mode,
+                             Object *proxy_from)
+{
+  float zup_mat[4][4];
+
+  /* get local or world matrix. */
+  if (mode == ABC_MATRIX_LOCAL && obj->parent) {
+    /* Note that this produces another matrix than the local matrix, due to
+     * constraints and modifiers as well as the obj->parentinv matrix. */
+    invert_m4_m4(obj->parent->imat, obj->parent->obmat);
+    mul_m4_m4m4(zup_mat, obj->parent->imat, obj->obmat);
+  }
+  else {
+    copy_m4_m4(zup_mat, obj->obmat);
+  }
+
+  if (proxy_from) {
+    mul_m4_m4m4(zup_mat, proxy_from->obmat, zup_mat);
+  }
+
+  copy_m44_axis_swap(r_yup_mat, zup_mat, ABC_YUP_FROM_ZUP);
+}