Transfer Data: add main core code and operators.

This add code needed to map a CD data layout from source mesh towards destination one,
and code needed to actually transfer data, using BKE's mesh remap generated data.

This allows to transfer most CD layers (vgroups, vcols, uvs...) as well as fake, boolean ones
(like smooth/sharp edges/faces, etc.). Some types are not yet transferable, mainly
shape keys, this is known TODO.

Data transfer can also use some advanced mixing in some cases (mostly, vgroups and vcols).

Notes:
* New transfer operators transfer data from active object towards selected ones.
* Modifier will be committed separately.
* Old weight transfer code (for vgroups) is kept for now, mostly because it is the only
  usable one in weightpaint mode (it transfers from selected object to active one,
  this is not sensible in Object mode, but needed in WeightPaint one). This will be addressed soon.

Again, heavily reviewed and enhanced by Campbell, thanks!

1 files changed, 17 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_deform.h b/source/blender/blenkernel/BKE_deform.h
index e203549fef5..08312035e40 100644
--- a/source/blender/blenkernel/BKE_deform.h
+++ b/source/blender/blenkernel/BKE_deform.h
@@ -39,6 +39,10 @@ struct Object;
 struct ListBase;
 struct bDeformGroup;
 struct MDeformVert;
+struct MVert;
+struct MEdge;
+struct MLoop;
+struct MPoly;
 
 struct bDeformGroup *BKE_defgroup_new(struct Object *ob, const char *name);
 void                 defgroup_copy_list(struct ListBase *lb1, struct ListBase *lb2);
@@ -85,6 +89,19 @@ void defvert_normalize_lock_map(struct MDeformVert *dvert,
                                 const bool *vgroup_subset, const int vgroup_tot,
                                 const bool *lock_flags, const int defbase_tot);
 
+/* Utilities to 'extract' a given vgroup into a simple float array, for verts, but also edges/polys/loops. */
+void BKE_defvert_extract_vgroup_to_vertweights(
+        struct MDeformVert *dvert, const int defgroup, const int num_verts, float *r_weights, const bool invert_vgroup);
+void BKE_defvert_extract_vgroup_to_edgeweights(
+        struct MDeformVert *dvert, const int defgroup, const int num_verts, struct MEdge *edges, const int num_edges,
+        float *r_weights, const bool invert_vgroup);
+void BKE_defvert_extract_vgroup_to_loopweights(
+        struct MDeformVert *dvert, const int defgroup, const int num_verts, struct MLoop *loops, const int num_loops,
+        float *r_weights, const bool invert_vgroup);
+void BKE_defvert_extract_vgroup_to_polyweights(
+        struct MDeformVert *dvert, const int defgroup, const int num_verts, struct MLoop *loops, const int num_loops,
+        struct MPoly *polys, const int num_polys, float *r_weights, const bool invert_vgroup);
+
 /* utility function, note that MAX_VGROUP_NAME chars is the maximum string length since its only
  * used with defgroups currently */