Cycles microdisplacement: ngons and attributes for subdivision meshes

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

1 files changed, 7 insertions, 2 deletions

diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index a9be2ae717a..b7021dbf7f1 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -573,8 +573,13 @@ typedef enum PrimitiveType {
 
 /* Attributes */
 
-#define ATTR_PRIM_TYPES		2
-#define ATTR_PRIM_CURVE		1
+typedef enum AttributePrimitive {
+	ATTR_PRIM_TRIANGLE = 0,
+	ATTR_PRIM_CURVE,
+	ATTR_PRIM_SUBD,
+
+	ATTR_PRIM_TYPES
+} AttributePrimitive;
 
 typedef enum AttributeElement {
 	ATTR_ELEMENT_NONE,