Multires: Initial work to get sculpting to work with OpenSubdiv

Allows to go to sculpt mode, do brush strokes, get out of sculpt mode
and have deformation preserved.

The issues currently is that the current implementation of CCG
storage is created from the limit surface, without displacement
taken into account. It is trivial to get displaced coordinates,
but it is more tricky to get displaced normals. This is something
to be solved next.

Another limitation is that this only works for sculpting at a maximal
multires level. There is code to be done to support propagation
of displacement onto a higher levels.

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_multires.h b/source/blender/blenkernel/BKE_multires.h
index 92755477d5e..26173643cbf 100644
--- a/source/blender/blenkernel/BKE_multires.h
+++ b/source/blender/blenkernel/BKE_multires.h
@@ -33,6 +33,7 @@
  */
 
 enum MultiresModifiedFlags;
+
 struct Depsgraph;
 struct DerivedMesh;
 struct MDisps;
@@ -42,6 +43,7 @@ struct Multires;
 struct MultiresModifierData;
 struct Object;
 struct Scene;
+struct SubdivCCG;
 
 struct MLoop;
 struct MVert;
@@ -126,6 +128,9 @@ bool multiresModifier_reshapeFromDeformModifier(
         struct MultiresModifierData *mmd,
         struct Object *ob,
         struct ModifierData *md);
+bool multiresModifier_reshapeFromCCG(
+        struct Object *dst,
+        struct SubdivCCG *subdiv_ccg);
 
 /* Subdivision integration, defined in multires_subdiv.c */