Cycles: Fix one-tile UDIM rendering

The code checked for the presence of more than one tile before
substituting the tile number into the filename, so if a one-tile
UDIM was used (or all but one tile were culled), the substitution
was skipped and as a result the file was not found.

With this change, the code explicitly tracks whether substitution
is required, avoiding this problem.

This also fixes another problem: The Environment texture never
does substitution since it doesn't support UDIMs, but before the
syncing code still inserted the placeholder into the filename if the
user selected a tiled background image.

1 files changed, 10 insertions, 2 deletions

diff --git a/intern/cycles/blender/blender_util.h b/intern/cycles/blender/blender_util.h
index efed96ec9f5..fa7646840c9 100644
--- a/intern/cycles/blender/blender_util.h
+++ b/intern/cycles/blender/blender_util.h
@@ -231,16 +231,24 @@ static inline int render_resolution_y(BL::RenderSettings &b_render)
   return b_render.resolution_y() * b_render.resolution_percentage() / 100;
 }
 
-static inline string image_user_file_path(BL::ImageUser &iuser, BL::Image &ima, int cfra)
+static inline string image_user_file_path(BL::ImageUser &iuser,
+                                          BL::Image &ima,
+                                          int cfra,
+                                          bool *is_tiled)
 {
+  if (is_tiled != NULL) {
+    *is_tiled = false;
+  }
+
   char filepath[1024];
   iuser.tile(0);
   BKE_image_user_frame_calc(NULL, iuser.ptr.data, cfra);
   BKE_image_user_file_path(iuser.ptr.data, ima.ptr.data, filepath);
-  if (ima.source() == BL::Image::source_TILED) {
+  if (ima.source() == BL::Image::source_TILED && is_tiled != NULL) {
     char *udim_id = strstr(filepath, "1001");
     if (udim_id != NULL) {
       memcpy(udim_id, "%04d", 4);
+      *is_tiled = true;
     }
   }
   return string(filepath);