Enhance vgroup handling when merging meshes.

We were looping over all vgroups in destination mesh and making string
comparison, for every vgroup of every vertex of merged mesh! Crazy!

Now we simply create a temp mapping of vgroup indices, seriously
simplifies things (and gives significant speedup when merging huge meshes
with lots of vgroups, here with quick stupid test went from 120ms in
vgroup merging to less than 5ms, 25 times quicker!).

1 files changed, 19 insertions, 15 deletions

diff --git a/source/blender/editors/mesh/meshtools.c b/source/blender/editors/mesh/meshtools.c
index 7faa1dd99e1..3f06ba2ced4 100644
--- a/source/blender/editors/mesh/meshtools.c
+++ b/source/blender/editors/mesh/meshtools.c
@@ -104,22 +104,26 @@ static void join_mesh_single(
 
 		/* vertex groups */
 		MDeformVert *dvert = CustomData_get(vdata, *vertofs, CD_MDEFORMVERT);
+		MDeformVert *dvert_src = CustomData_get(&me->vdata, 0, CD_MDEFORMVERT);
 
-		/* NB: vertex groups here are new version */
-		if (dvert) {
-			for (a = 0; a < me->totvert; a++) {
-				for (b = 0; b < dvert[a].totweight; b++) {
-					/*	Find the old vertex group */
-					bDeformGroup *dg, *odg = BLI_findlink(&base_src->object->defbase, dvert[a].dw[b].def_nr);
-					int index;
-					if (odg) {
-						/*	Search for a match in the new object, and set new index */
-						for (dg = ob_dst->defbase.first, index = 0; dg; dg = dg->next, index++) {
-							if (STREQ(dg->name, odg->name)) {
-								dvert[a].dw[b].def_nr = index;
-								break;
-							}
-						}
+		/* Remap to correct new vgroup indices, if needed. */
+		if (dvert_src) {
+			BLI_assert(dvert != NULL);
+
+			/* Build src to merged mapping of vgroup indices. */
+			bDeformGroup *dg_src;
+			int *vgroup_index_map = alloca(sizeof(*vgroup_index_map) * BLI_listbase_count(&base_src->object->defbase));
+			bool is_vgroup_remap_needed = false;
+
+			for (dg_src = base_src->object->defbase.first, b = 0; dg_src; dg_src = dg_src->next, b++) {
+				vgroup_index_map[b] = defgroup_name_index(ob_dst, dg_src->name);
+				is_vgroup_remap_needed = is_vgroup_remap_needed || (vgroup_index_map[b] != b);
+			}
+
+			if (is_vgroup_remap_needed) {
+				for (a = 0; a < me->totvert; a++) {
+					for (b = 0; b < dvert[a].totweight; b++) {
+						dvert[a].dw[b].def_nr = vgroup_index_map[dvert_src[a].dw[b].def_nr];
 					}
 				}
 			}