Fix #22213: applying deform modifier in front of multires modifier crashes,

should not do multires reshape in this case, but just regular apply.

3 files changed, 14 insertions, 7 deletions

diff --git a/source/blender/blenkernel/BKE_multires.h b/source/blender/blenkernel/BKE_multires.h
index e8bbb58a895..39fc795e6ff 100644
--- a/source/blender/blenkernel/BKE_multires.h
+++ b/source/blender/blenkernel/BKE_multires.h
@@ -47,7 +47,8 @@ void multires_force_external_reload(struct Object *ob);
 struct DerivedMesh *multires_dm_create_from_derived(struct MultiresModifierData*,
 	int local_mmd, struct DerivedMesh*, struct Object *, int, int);
 
-struct MultiresModifierData *find_multires_modifier(struct Scene *scene, struct Object *ob);
+struct MultiresModifierData *find_multires_modifier_before(struct Scene *scene,
+	struct ModifierData *lastmd);
 struct DerivedMesh *get_multires_dm(struct Scene *scene, struct MultiresModifierData *mmd,
 				struct Object *ob);
 void multiresModifier_join(struct Object *);
diff --git a/source/blender/blenkernel/intern/multires.c b/source/blender/blenkernel/intern/multires.c
index 76d82889cda..56d517f1e13 100644
--- a/source/blender/blenkernel/intern/multires.c
+++ b/source/blender/blenkernel/intern/multires.c
@@ -75,11 +75,11 @@ DerivedMesh *get_multires_dm(Scene *scene, MultiresModifierData *mmd, Object *ob
 	return dm;
 }
 
-MultiresModifierData *find_multires_modifier(Scene *scene, Object *ob)
+MultiresModifierData *find_multires_modifier_before(Scene *scene, ModifierData *lastmd)
 {
 	ModifierData *md;
 
-	for(md = ob->modifiers.first; md; md = md->next) {
+	for(md = lastmd; md; md = md->prev) {
 		if(md->type == eModifierType_Multires) {
 			if (modifier_isEnabled(scene, md, eModifierMode_Realtime))
 				return (MultiresModifierData*)md;
@@ -249,6 +249,9 @@ int multiresModifier_reshapeFromDeformMod(Scene *scene, MultiresModifierData *mm
 	int numVerts, result;
 	float (*deformedVerts)[3];
 
+	if(multires_get_level(ob, mmd, 0) == 0)
+		return 0;
+
 	/* Create DerivedMesh for deformation modifier */
 	dm = get_multires_dm(scene, mmd, ob);
 	numVerts= dm->getNumVerts(dm);
diff --git a/source/blender/editors/object/object_modifier.c b/source/blender/editors/object/object_modifier.c
index ec142d23a1f..0661b675668 100644
--- a/source/blender/editors/object/object_modifier.c
+++ b/source/blender/editors/object/object_modifier.c
@@ -399,7 +399,7 @@ static int modifier_apply_obdata(ReportList *reports, Scene *scene, Object *ob,
 	if (ob->type==OB_MESH) {
 		DerivedMesh *dm;
 		Mesh *me = ob->data;
-		MultiresModifierData *mmd= find_multires_modifier(scene, ob);
+		MultiresModifierData *mmd= find_multires_modifier_before(scene, md);
 
 		if( me->key) {
 			BKE_report(reports, RPT_ERROR, "Modifier cannot be applied to Mesh with Shape Keys");
@@ -412,12 +412,15 @@ static int modifier_apply_obdata(ReportList *reports, Scene *scene, Object *ob,
 		if(md->type == eModifierType_Multires)
 			multires_force_update(ob);
 
-		if (mmd && mti->type==eModifierTypeType_OnlyDeform) {
-			multiresModifier_reshapeFromDeformMod (scene, mmd, ob, md);
+		if (mmd && mmd->totlvl && mti->type==eModifierTypeType_OnlyDeform) {
+			if(!multiresModifier_reshapeFromDeformMod (scene, mmd, ob, md)) {
+				BKE_report(reports, RPT_ERROR, "Multires modifier returned error, skipping apply");
+				return 0;
+			}
 		} else {
 			dm = mesh_create_derived_for_modifier(scene, ob, md);
 			if (!dm) {
-				BKE_report(reports, RPT_ERROR, "Modifier is returned error, skipping apply");
+				BKE_report(reports, RPT_ERROR, "Modifier returned error, skipping apply");
 				return 0;
 			}