Fix T45695: Assigning material reverts MaterialSlot.link

Setting the material was resetting the link bit, this is OK from the UI,
confusing for scripts.

1 files changed, 13 insertions, 8 deletions

diff --git a/source/blender/blenkernel/intern/material.c b/source/blender/blenkernel/intern/material.c
index 283c7a6fc88..dd69de4877f 100644
--- a/source/blender/blenkernel/intern/material.c
+++ b/source/blender/blenkernel/intern/material.c
@@ -879,8 +879,20 @@ void assign_material(Object *ob, Material *ma, short act, int assign_type)
 		*totcolp = act;
 	}
 
+	if (act > ob->totcol) {
+		/* Need more space in the material arrays */
+		ob->mat = MEM_recallocN_id(ob->mat, sizeof(void *) * act, "matarray2");
+		ob->matbits = MEM_recallocN_id(ob->matbits, sizeof(char) * act, "matbits1");
+		ob->totcol = act;
+	}
+
 	/* Determine the object/mesh linking */
-	if (assign_type == BKE_MAT_ASSIGN_USERPREF && ob->totcol && ob->actcol) {
+	if (assign_type == BKE_MAT_ASSIGN_EXISTING) {
+		/* keep existing option (avoid confusion in scripts),
+		 * intentionally ignore userpref (default to obdata). */
+		bit = ob->matbits[act - 1];
+	}
+	else if (assign_type == BKE_MAT_ASSIGN_USERPREF && ob->totcol && ob->actcol) {
 		/* copy from previous material */
 		bit = ob->matbits[ob->actcol - 1];
 	}
@@ -898,13 +910,6 @@ void assign_material(Object *ob, Material *ma, short act, int assign_type)
 				break;
 		}
 	}
-
-	if (act > ob->totcol) {
-		/* Need more space in the material arrays */
-		ob->mat = MEM_recallocN_id(ob->mat, sizeof(void *) * act, "matarray2");
-		ob->matbits = MEM_recallocN_id(ob->matbits, sizeof(char) * act, "matbits1");
-		ob->totcol = act;
-	}
 	
 	/* do it */