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, 2 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_displist.h b/source/blender/blenkernel/BKE_displist.h
index 04f3aadbe3c..979ed31fb20 100644
--- a/source/blender/blenkernel/BKE_displist.h
+++ b/source/blender/blenkernel/BKE_displist.h
@@ -36,6 +36,7 @@
 #define BKE_DISPLIST_H
 
 #include "DNA_customdata_types.h"
+#include "BKE_customdata.h"
 
 /* dl->type */
 #define DL_POLY                 0
@@ -109,7 +110,7 @@ extern void addnormalsDispList(struct Object *ob, struct ListBase *lb);
 extern void count_displist(struct ListBase *lb, int *totvert, int *totface);
 extern void freedisplist(struct ListBase *lb);
 extern int displist_has_faces(struct ListBase *lb);
-extern void makeDerivedMesh(struct Object *ob);
+extern void makeDerivedMesh(struct Object *ob, CustomDataMask dataMask);
 extern void makeDispListSurf(struct Object *ob, struct ListBase *dispbase, int forRender);
 extern void makeDispListCurveTypes(struct Object *ob, int forOrco);
 extern void makeDispListMBall(struct Object *ob);