obj: vertex colors support in importer and exporter

Adds support for vertex colors to OBJ I/O.

Importer:

- Supports both "xyzrgb" and "MRGB" vertex color formats.
- Whenever vertex color is present in the file for a model, it is
  imported and a Color attribute is created (per-vertex, full float
  color data type). Color coming from the file is assumed to be sRGB,
  and is converted to linear upon import.

Exporter:

- Option to export the vertex colors. Defaults to "off", since not
  all 3rd party software supports vertex colors.
- When the option is "on", if a mesh has a color attribute layer,
  the active one is exported in "xyzrgb" form. If the mesh has
  per-face-corner colors, they are averaged on the vertices.
  Colors are converted from linear to sRGB upon export.

Reviewed By: Howard Trickey
Differential Revision: https://developer.blender.org/D15159

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/io/wavefront_obj/exporter/obj_export_mesh.hh b/source/blender/io/wavefront_obj/exporter/obj_export_mesh.hh
index 91213ec8152..ee2e6227700 100644
--- a/source/blender/io/wavefront_obj/exporter/obj_export_mesh.hh
+++ b/source/blender/io/wavefront_obj/exporter/obj_export_mesh.hh
@@ -241,6 +241,11 @@ class OBJMesh : NonCopyable {
     return i < 0 || i >= poly_order_.size() ? i : poly_order_[i];
   }
 
+  Mesh *get_mesh() const
+  {
+    return export_mesh_eval_;
+  }
+
  private:
   /**
    * Free the mesh if _the exporter_ created it.