Add tessellation data to DerivedMesh (LoopTri)

This stores loop indices into the loop array giving easier acess
to data such as vertex-colors and UV's,
removing the need to store an MFace duplicate of custom-data.

This doesn't yet move all internal code from MFace to LoopTri just yet.

Only applies to:
- opengl drawing
- sculpting (pbvh)
- vertex/weight paint

Thanks to @psy-fi for review, fixes and improvements to drawing!

1 files changed, 11 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_meshdata_types.h b/source/blender/makesdna/DNA_meshdata_types.h
index b76f40c884d..12c6e0ec0a5 100644
--- a/source/blender/makesdna/DNA_meshdata_types.h
+++ b/source/blender/makesdna/DNA_meshdata_types.h
@@ -89,6 +89,14 @@ typedef struct MLoop {
 	unsigned int e;  /* edge index */
 } MLoop;
 
+/* runtime only */
+#
+#
+typedef struct MLoopTri {
+	unsigned int tri[3];
+	unsigned int poly;
+} MLoopTri;
+
 typedef struct MTexPoly {
 	struct Image *tpage;
 	char flag, transp;
@@ -345,6 +353,9 @@ enum {
 #define ME_POLY_LOOP_PREV(mloop, mp, i)  (&(mloop)[(mp)->loopstart + (((i) + (mp)->totloop - 1) % (mp)->totloop)])
 #define ME_POLY_LOOP_NEXT(mloop, mp, i)  (&(mloop)[(mp)->loopstart + (((i) + 1) % (mp)->totloop)])
 
+/* number of tri's that make up this polygon once tessellated */
+#define ME_POLY_TRI_TOT(mp) ((mp)->totloop - 2)
+
 /* mselect->type */
 enum {
 	ME_VSEL = 0,