Fix #34009: multi user curves + deform modifier behavior

Issue was caused by storing BB calculated from final displist in
Curve datablock and not having Object's BB at all. This is not
clear at how could have been worked for so long.

Changed it so Curve's BB is calculated from non-deformed displist,
which matches BKE_object_min_max and BKE_curve_texspace_calc and
made it so Object's BB would be calculated from final displist.

1 files changed, 38 insertions, 29 deletions

diff --git a/source/blender/blenkernel/intern/displist.c b/source/blender/blenkernel/intern/displist.c
index 23b0d3e6e22..ada33691c15 100644
--- a/source/blender/blenkernel/intern/displist.c
+++ b/source/blender/blenkernel/intern/displist.c
@@ -63,6 +63,7 @@
 #include "BLO_sys_types.h" // for intptr_t support
 
 static void boundbox_displist(Object *ob);
+static void boundbox_dispbase(BoundBox *bb, ListBase *dispbase);
 
 void BKE_displist_elem_free(DispList *dl)
 {
@@ -1598,15 +1599,15 @@ void BKE_displist_make_curveTypes(Scene *scene, Object *ob, int forOrco)
 
 	if (ob->derivedFinal) {
 		DM_set_object_boundbox(ob, ob->derivedFinal);
+
+		/* always keep curve's  BB in sync with non-deformed displist */
+		if (cu->bb == NULL)
+			cu->bb = MEM_callocN(sizeof(BoundBox), "boundbox");
+
+		boundbox_dispbase(cu->bb, &cu->disp);
 	}
 	else {
 		boundbox_displist(ob);
-
-		/* if there is no derivedMesh, object's boundbox is unneeded */
-		if (ob->bb) {
-			MEM_freeN(ob->bb);
-			ob->bb = NULL;
-		}
 	}
 }
 
@@ -1642,42 +1643,50 @@ float *BKE_displist_make_orco(Scene *scene, Object *ob, DerivedMesh *derivedFina
 	return orco;
 }
 
-/* this is confusing, there's also min_max_object, appplying the obmat... */
-static void boundbox_displist(Object *ob)
+static void boundbox_dispbase(BoundBox *bb, ListBase *dispbase)
 {
-	BoundBox *bb = NULL;
 	float min[3], max[3];
 	DispList *dl;
 	float *vert;
 	int a, tot = 0;
+	int doit = 0;
 
 	INIT_MINMAX(min, max);
 
+	for (dl = dispbase->first; dl; dl = dl->next) {
+		tot = (dl->type == DL_INDEX3) ? dl->nr : dl->nr * dl->parts;
+		vert = dl->verts;
+		for (a = 0; a < tot; a++, vert += 3) {
+			minmax_v3v3_v3(min, max, vert);
+		}
+		doit |= (tot != 0);
+	}
+
+	if (!doit) {
+		/* there's no geometry in displist, use zero-sized boundbox */
+		zero_v3(min);
+		zero_v3(max);
+	}
+
+	BKE_boundbox_init_from_minmax(bb, min, max);
+}
+
+/* this is confusing, there's also min_max_object, appplying the obmat... */
+static void boundbox_displist(Object *ob)
+{
 	if (ELEM3(ob->type, OB_CURVE, OB_SURF, OB_FONT)) {
 		Curve *cu = ob->data;
-		int doit = 0;
 
-		if (cu->bb == NULL) cu->bb = MEM_callocN(sizeof(BoundBox), "boundbox");
-		bb = cu->bb;
+		/* calculate curve's BB based on non-deformed displist */
+		if (cu->bb == NULL)
+			cu->bb = MEM_callocN(sizeof(BoundBox), "boundbox");
 
-		for (dl = ob->disp.first; dl; dl = dl->next) {
-			tot = (dl->type == DL_INDEX3) ? dl->nr : dl->nr * dl->parts;
-			vert = dl->verts;
-			for (a = 0; a < tot; a++, vert += 3) {
-				minmax_v3v3_v3(min, max, vert);
-			}
-			doit = (tot != 0);
-		}
+		boundbox_dispbase(cu->bb, &cu->disp);
 
-		if (!doit) {
-			/* there's no geometry in displist, use zero-sized boundbox */
-			zero_v3(min);
-			zero_v3(max);
-		}
-
-	}
+		/* object's BB is calculated from final displist */
+		if (ob->bb == NULL)
+			ob->bb = MEM_callocN(sizeof(BoundBox), "boundbox");
 
-	if (bb) {
-		BKE_boundbox_init_from_minmax(bb, min, max);
+		boundbox_dispbase(ob->bb, &ob->disp);
 	}
 }