UDIM: Support tile sets that do not start at 1001

Removes the artificial requirement that UDIM tile sets start at 1001.
Blender was already capable of handling sparse tile sets (non-contiguous
tiles) so the restriction around starting at 1001 was unnecessary in
general.

This required fixing a few UDIM-related python bugs around manually
updating the `tile_number` field on images as well. See the differential
for details. No script changes are necessary but they will now work,
correctly, in many more cases.

Differential Revision: https://developer.blender.org/D11859

1 files changed, 5 insertions, 1 deletions

diff --git a/intern/cycles/blender/blender_util.h b/intern/cycles/blender/blender_util.h
index 82da3512269..d441575e8af 100644
--- a/intern/cycles/blender/blender_util.h
+++ b/intern/cycles/blender/blender_util.h
@@ -246,7 +246,11 @@ static inline string image_user_file_path(BL::ImageUser &iuser,
 
   string filepath_str = string(filepath);
   if (load_tiled && ima.source() == BL::Image::source_TILED) {
-    string_replace(filepath_str, "1001", "<UDIM>");
+    string udim;
+    if (ima.tiles.length() > 0) {
+      udim = to_string(ima.tiles[0].number());
+    }
+    string_replace(filepath_str, udim, "<UDIM>");
   }
   return filepath_str;
 }