io_mesh_uv_layout/__init__.py

@@ -60,9 +60,9 @@ class ExportUVLayout(bpy.types.Operator):
             ('NONE', "None",
              "Export only UVs in the [0, 1] range"),
             ('UDIM', "UDIM",
-             "Export tiles in the UDIM notation: 1001 + u-tile + 10*v-tile"),
-            ('UV', "UV Tiles",
-             "Export tiles in the UV notation: u(u-tile + 1)_v(v-tile + 1)"),
+             "Export tiles in the UDIM numbering scheme: 1001 + u-tile + 10*v-tile"),
+            ('UV', "UVTILE",
+             "Export tiles in the UVTILE numbering scheme: u(u-tile + 1)_v(v-tile + 1)"),
         ),
         description="Choose whether to export only the [0, 1 range], or all UV tiles",
         default='NONE',
@@ -165,7 +165,7 @@ class ExportUVLayout(bpy.types.Operator):
         if match:
             filename = match.groups()[0]
 
-        for tile in tiles:
+        for tile in sorted(tiles):
             filepath = os.path.join(dirname, filename)
             if self.export_tiles == 'UDIM':
                 filepath += f".{1001 + tile[0] + tile[1] * 10:04}"
@@ -210,7 +210,16 @@ class ExportUVLayout(bpy.types.Operator):
         tiles = set()
         for poly in polygon_data:
             for uv in poly[0]:
-                tiles.add((floor(uv[0]), floor(uv[1])))
+                # Ignore UVs at corners - precisely touching the right or upper edge
+                # of a tile should not load its right/upper neighbor as well.
+                # From intern/cycles/scene/attribute.cpp
+                u, v = (uv[0], uv[1])
+                x, y = (floor(u), floor(v))
+                if (x > 0 and (u < x + 1e-6)):
+                    x -= 1
+                if (y > 0 and (v < y + 1e-6)):
+                    y -= 1
+                tiles.add((x, y))
         return tiles
 
     @staticmethod