Fix T49860: Copying vgroups between objects sharing the same obdata was not possible.

Pretty straight forward actually, just do not bother about obdata part
of vgroups in that case, only copy object part of it.

And let's curse once again those stuff spread accross several types of
data-blocks...

1 files changed, 33 insertions, 28 deletions

diff --git a/source/blender/editors/object/object_vgroup.c b/source/blender/editors/object/object_vgroup.c
index 56f59dca9a1..3c406764157 100644
--- a/source/blender/editors/object/object_vgroup.c
+++ b/source/blender/editors/object/object_vgroup.c
@@ -363,8 +363,8 @@ void ED_vgroup_parray_remove_zero(MDeformVert **dvert_array, const int dvert_tot
 /* matching index only */
 bool ED_vgroup_array_copy(Object *ob, Object *ob_from)
 {
-	MDeformVert **dvert_array_from, **dvf;
-	MDeformVert **dvert_array, **dv;
+	MDeformVert **dvert_array_from = NULL, **dvf;
+	MDeformVert **dvert_array = NULL, **dv;
 	int dvert_tot_from;
 	int dvert_tot;
 	int i;
@@ -375,26 +375,30 @@ bool ED_vgroup_array_copy(Object *ob, Object *ob_from)
 	if (ob == ob_from)
 		return true;
 
-	ED_vgroup_parray_alloc(ob_from->data, &dvert_array_from, &dvert_tot_from, false);
-	ED_vgroup_parray_alloc(ob->data, &dvert_array, &dvert_tot, false);
-
-	if ((dvert_array == NULL) && (dvert_array_from != NULL) && BKE_object_defgroup_data_create(ob->data)) {
+	/* in case we copy vgroup between two objects using same data, we only have to care about object side of things. */
+	if (ob->data != ob_from->data) {
+		ED_vgroup_parray_alloc(ob_from->data, &dvert_array_from, &dvert_tot_from, false);
 		ED_vgroup_parray_alloc(ob->data, &dvert_array, &dvert_tot, false);
-		new_vgroup = true;
-	}
 
-	if (dvert_tot == 0 || (dvert_tot != dvert_tot_from) || dvert_array_from == NULL || dvert_array == NULL) {
+		if ((dvert_array == NULL) && (dvert_array_from != NULL) && BKE_object_defgroup_data_create(ob->data)) {
+			ED_vgroup_parray_alloc(ob->data, &dvert_array, &dvert_tot, false);
+			new_vgroup = true;
+		}
 
-		if (dvert_array) MEM_freeN(dvert_array);
-		if (dvert_array_from) MEM_freeN(dvert_array_from);
+		if (dvert_tot == 0 || (dvert_tot != dvert_tot_from) || dvert_array_from == NULL || dvert_array == NULL) {
+			if (dvert_array)
+				MEM_freeN(dvert_array);
+			if (dvert_array_from)
+				MEM_freeN(dvert_array_from);
 
-		if (new_vgroup == true) {
-			/* free the newly added vgroup since it wasn't compatible */
-			BKE_object_defgroup_remove_all(ob);
-		}
+			if (new_vgroup == true) {
+				/* free the newly added vgroup since it wasn't compatible */
+				BKE_object_defgroup_remove_all(ob);
+			}
 
-		/* if true: both are 0 and nothing needs changing, consider this a success */
-		return (dvert_tot == dvert_tot_from);
+			/* if true: both are 0 and nothing needs changing, consider this a success */
+			return (dvert_tot == dvert_tot_from);
+		}
 	}
 
 	/* do the copy */
@@ -412,22 +416,23 @@ bool ED_vgroup_array_copy(Object *ob, Object *ob_from)
 		MEM_freeN(remap);
 	}
 
-	dvf = dvert_array_from;
-	dv = dvert_array;
+	if (dvert_array_from != NULL && dvert_array != NULL) {
+		dvf = dvert_array_from;
+		dv = dvert_array;
 
-	for (i = 0; i < dvert_tot; i++, dvf++, dv++) {
-		if ((*dv)->dw)
-			MEM_freeN((*dv)->dw);
+		for (i = 0; i < dvert_tot; i++, dvf++, dv++) {
+			MEM_SAFE_FREE((*dv)->dw);
+			*(*dv) = *(*dvf);
 
-		*(*dv) = *(*dvf);
+			if ((*dv)->dw) {
+				(*dv)->dw = MEM_dupallocN((*dv)->dw);
+			}
+		}
 
-		if ((*dv)->dw)
-			(*dv)->dw = MEM_dupallocN((*dv)->dw);
+		MEM_freeN(dvert_array);
+		MEM_freeN(dvert_array_from);
 	}
 
-	MEM_freeN(dvert_array);
-	MEM_freeN(dvert_array_from);
-
 	return true;
 }