Fix crash when creating new faces in edit mode

- Do not check corners count if totdisp is set to 0
- Allocate memory for such mdisps to prevent the whole disp layer erasing

1 files changed, 16 insertions, 2 deletions

diff --git a/source/blender/blenkernel/intern/multires.c b/source/blender/blenkernel/intern/multires.c
index f4e9dcf742b..5dfae6599aa 100644
--- a/source/blender/blenkernel/intern/multires.c
+++ b/source/blender/blenkernel/intern/multires.c
@@ -1614,17 +1614,31 @@ void multires_topology_changed(Object *ob)
 {
 	Mesh *me= (Mesh*)ob->data;
 	MDisps *mdisp= NULL;
-	int i;
+	int i, totlvl;
 
 	CustomData_external_read(&me->fdata, &me->id, CD_MASK_MDISPS, me->totface);
 	mdisp= CustomData_get_layer(&me->fdata, CD_MDISPS);
 
 	if(!mdisp) return;
 
+	totlvl= get_levels_from_disps(ob);
+
 	for(i = 0; i < me->totface; i++, mdisp++) {
-		int corners= multires_mdisp_corners(mdisp);
+		int corners= 0;
 		int nvert= me->mface[i].v4 ? 4 : 3;
 
+		/* allocate memory for mdisp, the whole disp layer would be erased otherwise */
+		if(!mdisp->totdisp) {
+			int side = multires_side_tot[totlvl];
+
+			mdisp->totdisp= nvert*side*side;
+			mdisp->disps= MEM_callocN(mdisp->totdisp*sizeof(float)*3, "mdisp topology");
+
+			continue;
+		}
+
+		corners= multires_mdisp_corners(mdisp);
+
 		if(corners!=nvert) {
 			mdisp->totdisp= (mdisp->totdisp/corners)*nvert;