Fix T81247: Constrain selected UVs to correct UDIM

With Constrain to Image Bounds selected, UVs will be constrained to the
correct/closest UDIM if the image is tiled.
UVs will be constrained to the 0-1 UV space if the image is not tiled.
This will override the present behavior of always constraining selected
UVs to the 0-1 UV space (UDIM 1001).

Reviewed By: campbellbarton

Ref D11202

1 files changed, 44 insertions, 19 deletions

diff --git a/source/blender/editors/transform/transform_convert.c b/source/blender/editors/transform/transform_convert.c
index c021c084a23..7239bed1eeb 100644
--- a/source/blender/editors/transform/transform_convert.c
+++ b/source/blender/editors/transform/transform_convert.c
@@ -37,6 +37,7 @@
 #include "BKE_context.h"
 #include "BKE_fcurve.h"
 #include "BKE_global.h"
+#include "BKE_image.h"
 #include "BKE_layer.h"
 #include "BKE_lib_id.h"
 #include "BKE_main.h"
@@ -505,9 +506,27 @@ bool clipUVTransform(TransInfo *t, float vec[2], const bool resize)
   bool clipx = true, clipy = true;
   float min[2], max[2];
 
-  min[0] = min[1] = 0.0f;
-  max[0] = t->aspect[0];
-  max[1] = t->aspect[1];
+  /* Check if the current image in UV editor is a tiled image or not. */
+  const SpaceImage *sima = t->area->spacedata.first;
+  const Image *image = sima->image;
+  const bool is_tiled_image = image && (image->source == IMA_SRC_TILED);
+  /* Stores the coordinates of the closest UDIM tile.
+   * Also acts as an offset to the tile from the origin of UV space. */
+  float base_offset[2] = {0.0f, 0.0f};
+
+  /* If tiled image then constrain to correct/closest UDIM tile, else 0-1 UV space. */
+  if (is_tiled_image) {
+    int nearest_tile_index = BKE_image_find_nearest_tile(image, t->center_global);
+    if (nearest_tile_index != -1) {
+      nearest_tile_index -= 1001;
+      /* Getting coordinates of nearest tile from the tile index. */
+      base_offset[0] = nearest_tile_index % 10;
+      base_offset[1] = nearest_tile_index / 10;
+    }
+  }
+
+  min[0] = min[1] = FLT_MAX;
+  max[0] = max[1] = FLT_MIN;
 
   FOREACH_TRANS_DATA_CONTAINER (t, tc) {
 
@@ -520,42 +539,48 @@ bool clipUVTransform(TransInfo *t, float vec[2], const bool resize)
   }
 
   if (resize) {
-    if (min[0] < 0.0f && t->center_global[0] > 0.0f && t->center_global[0] < t->aspect[0] * 0.5f) {
-      vec[0] *= t->center_global[0] / (t->center_global[0] - min[0]);
+    if (min[0] < base_offset[0] && t->center_global[0] > base_offset[0] &&
+        t->center_global[0] < base_offset[0] + (t->aspect[0] * 0.5f)) {
+      vec[0] *= (t->center_global[0] - base_offset[0]) / (t->center_global[0] - min[0]);
     }
-    else if (max[0] > t->aspect[0] && t->center_global[0] < t->aspect[0]) {
-      vec[0] *= (t->center_global[0] - t->aspect[0]) / (t->center_global[0] - max[0]);
+    else if (max[0] > (base_offset[0] + t->aspect[0]) &&
+             t->center_global[0] < (base_offset[0] + t->aspect[0])) {
+      vec[0] *= (t->center_global[0] - (base_offset[0] + t->aspect[0])) /
+                (t->center_global[0] - max[0]);
     }
     else {
       clipx = 0;
     }
 
-    if (min[1] < 0.0f && t->center_global[1] > 0.0f && t->center_global[1] < t->aspect[1] * 0.5f) {
-      vec[1] *= t->center_global[1] / (t->center_global[1] - min[1]);
+    if (min[1] < base_offset[1] && t->center_global[1] > base_offset[1] &&
+        t->center_global[1] < base_offset[1] + (t->aspect[1] * 0.5f)) {
+      vec[1] *= (t->center_global[1] - base_offset[1]) / (t->center_global[1] - min[1]);
     }
-    else if (max[1] > t->aspect[1] && t->center_global[1] < t->aspect[1]) {
-      vec[1] *= (t->center_global[1] - t->aspect[1]) / (t->center_global[1] - max[1]);
+    else if (max[1] > (base_offset[1] + t->aspect[1]) &&
+             t->center_global[1] < (base_offset[1] + t->aspect[1])) {
+      vec[1] *= (t->center_global[1] - (base_offset[1] + t->aspect[1])) /
+                (t->center_global[1] - max[1]);
     }
     else {
       clipy = 0;
     }
   }
   else {
-    if (min[0] < 0.0f) {
-      vec[0] -= min[0];
+    if (min[0] < base_offset[0]) {
+      vec[0] += base_offset[0] - min[0];
     }
-    else if (max[0] > t->aspect[0]) {
-      vec[0] -= max[0] - t->aspect[0];
+    else if (max[0] > base_offset[0] + t->aspect[0]) {
+      vec[0] -= max[0] - base_offset[0] - t->aspect[0];
     }
     else {
       clipx = 0;
     }
 
-    if (min[1] < 0.0f) {
-      vec[1] -= min[1];
+    if (min[1] < base_offset[1]) {
+      vec[1] += base_offset[1] - min[1];
     }
-    else if (max[1] > t->aspect[1]) {
-      vec[1] -= max[1] - t->aspect[1];
+    else if (max[1] > base_offset[1] + t->aspect[1]) {
+      vec[1] -= max[1] - base_offset[1] - t->aspect[1];
     }
     else {
       clipy = 0;