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, 11 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_subdiv_ccg.h b/source/blender/blenkernel/BKE_subdiv_ccg.h
index 59a31e158cc..c760fb04fd3 100644
--- a/source/blender/blenkernel/BKE_subdiv_ccg.h
+++ b/source/blender/blenkernel/BKE_subdiv_ccg.h
@@ -114,6 +114,17 @@ typedef struct SubdivCCG {
 	/* TODO(sergey): Consider adding CD layers here, so we can draw final mesh
 	 * from grids, and have UVs and such work.
 	 */
+
+	/* Integration with sculpting. */
+	/* TODO(sergey): Is this really best way to go? Kind of annoying to have
+	 * such use-related flags in a more or less generic structure.
+	 */
+	struct {
+		/* Corresponds to MULTIRES_COORDS_MODIFIED. */
+		bool coords;
+		/* Corresponds to MULTIRES_HIDDEN_MODIFIED. */
+		bool hidden;
+	} dirty;
 } SubdivCCG;
 
 /* Create real hi-res CCG from subdivision.