Modifier Stack: Limit calculation to required data.

This commit upgrades the modifier stack to only calculate the data which is
needed, either by modifiers further down the stack or by other functions at
the end of the stack (e.g. drawing functions).

This speeds up modifier stack recalculation, especially where vertex
groups and UV coordinates are concerned. For example, a mesh with an Armature
modifier followed by a Subsurf modifier would previously have required the
Subsurf modifier to interpolate all the vertex groups in the mesh, slowing
down modifier calculations considerably. With this update, vertex group data
is not propagated beyond the Armature modifier, so calculations are faster.

Note that this depends on the order of modifiers in the stack. If the Armature
and Subsurf modifiers were swapped in the above example, the Subsurf modifier
would have to interpolate vertex groups, as they are needed by the Armature
modifier.

1 files changed, 12 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_customdata_types.h b/source/blender/makesdna/DNA_customdata_types.h
index 08b0345af8d..00c303c0357 100644
--- a/source/blender/makesdna/DNA_customdata_types.h
+++ b/source/blender/makesdna/DNA_customdata_types.h
@@ -62,6 +62,18 @@ typedef struct CustomData {
 #define CD_FLAGS		9
 #define CD_NUMTYPES		10
 
+/* Bits for CustomDataMask */
+#define CD_MASK_MVERT		(1 << CD_MVERT)
+#define CD_MASK_MSTICKY		(1 << CD_MSTICKY)
+#define CD_MASK_MDEFORMVERT	(1 << CD_MDEFORMVERT)
+#define CD_MASK_MEDGE		(1 << CD_MEDGE)
+#define CD_MASK_MFACE		(1 << CD_MFACE)
+#define CD_MASK_MTFACE		(1 << CD_MTFACE)
+#define CD_MASK_MCOL		(1 << CD_MCOL)
+#define CD_MASK_ORIGINDEX	(1 << CD_ORIGINDEX)
+#define CD_MASK_NORMAL		(1 << CD_NORMAL)
+#define CD_MASK_FLAGS		(1 << CD_FLAGS)
+
 /* CustomData.flag */
 
 /* indicates layer should not be copied by CustomData_from_template or