1 files changed, 23 insertions, 7 deletions

diff --git a/source/blender/blenkernel/intern/material.c b/source/blender/blenkernel/intern/material.c
index 73b64e6efb3..468f735257a 100644
--- a/source/blender/blenkernel/intern/material.c
+++ b/source/blender/blenkernel/intern/material.c
@@ -770,6 +770,7 @@ int BKE_object_material_count_eval(Object *ob)
 
 void BKE_id_material_eval_assign(ID *id, int slot, Material *material)
 {
+  BLI_assert(slot >= 1);
   Material ***materials_ptr = BKE_id_material_array_p(id);
   short *len_ptr = BKE_id_material_len_p(id);
   if (ELEM(NULL, materials_ptr, len_ptr)) {
@@ -793,6 +794,21 @@ void BKE_id_material_eval_assign(ID *id, int slot, Material *material)
   (*materials_ptr)[slot_index] = material;
 }
 
+/**
+ * Add an empty material slot if the id has no material slots. This material slot allows the
+ * material to be overwritten by object-linked materials.
+ */
+void BKE_id_material_eval_ensure_default_slot(ID *id)
+{
+  short *len_ptr = BKE_id_material_len_p(id);
+  if (len_ptr == NULL) {
+    return;
+  }
+  if (*len_ptr == 0) {
+    BKE_id_material_eval_assign(id, 1, NULL);
+  }
+}
+
 Material *BKE_gpencil_material(Object *ob, short act)
 {
   Material *ma = BKE_object_material_get(ob, act);
@@ -1497,16 +1513,16 @@ void BKE_texpaint_slots_refresh_object(Scene *scene, struct Object *ob)
 }
 
 struct FindTexPaintNodeData {
-  bNode *node;
-  short iter_index;
-  short index;
+  Image *ima;
+  bNode *r_node;
 };
 
 static bool texpaint_slot_node_find_cb(bNode *node, void *userdata)
 {
   struct FindTexPaintNodeData *find_data = userdata;
-  if (find_data->iter_index++ == find_data->index) {
-    find_data->node = node;
+  Image *ima = (Image *)node->id;
+  if (find_data->ima == ima) {
+    find_data->r_node = node;
     return false;
   }
 
@@ -1515,10 +1531,10 @@ static bool texpaint_slot_node_find_cb(bNode *node, void *userdata)
 
 bNode *BKE_texpaint_slot_material_find_node(Material *ma, short texpaint_slot)
 {
-  struct FindTexPaintNodeData find_data = {NULL, 0, texpaint_slot};
+  struct FindTexPaintNodeData find_data = {ma->texpaintslot[texpaint_slot].ima, NULL};
   ntree_foreach_texnode_recursive(ma->nodetree, texpaint_slot_node_find_cb, &find_data);
 
-  return find_data.node;
+  return find_data.r_node;
 }
 
 /* r_col = current value, col = new value, (fac == 0) is no change */