Problem was zero length normal caused by a precision issue in patch evaluation.
This is somewhat of a quick fix, but is better than allowing possible NaNs to
occur and cause problems elsewhere.
These latter can cause MSVC debug asserts if the array is empty. With C++11
we'll be able to do this for std::vector later. This hopefully fixes an assert
in the Cycles subdivision code.
Enables Catmull-Clark subdivision meshes with support for creases and attribute
subdivision. Still waiting on OpenSubdiv to fully support face varying
interpolation for subdividing uv coordinates tho. Also there may be some
inconsistencies with Blender's subdivision which will be resolved at a
later time.
Code for reading patch tables and creating patch maps is borrowed
from OpenSubdiv.
Reviewed By: brecht
Differential Revision: https://developer.blender.org/D2111
This adds support for ngons and attributes on subdivision meshes. Ngons are
needed for proper attribute interpolation as well as correct Catmull-Clark
subdivision. Several changes are made to achieve this:
- new primitive `SubdFace` added to `Mesh`
- 3 more textures are used to store info on patches from subd meshes
- Blender export uses loop interface instead of tessface for subd meshes
- `Attribute` class is updated with a simplified way to pass primitive counts
around and to support ngons.
- extra points for ngons are generated for O(1) attribute interpolation
- curves are temporally disabled on subd meshes to avoid various bugs with
implementation
- old unneeded code is removed from `subd/`
- various fixes and improvements
Reviewed By: brecht
Differential Revision: https://developer.blender.org/D2108
