UV: Pack to closest/active UDIM

Implements T78397
Extends the functionality of pack islands operator to allow packing UVs
to either the closest or active UDIM tile.
This provides 2 new options for packing UVs :

* Closest UDIM: Selected UVs will be packed to the UDIM tile they were
  placed on. If not present on a valid UDIM tile, the UVs will be packed
  to the closest UDIM in UV space
* Active UDIM: Selected UVs will be packed to the active UDIM image tile
  In case, no image is present in the UV editor, then UVs will be packed
  to the tile on the UDIM grid where the 2D cursor is located.

Reviewed By: campbellbarton

Maniphest Tasks: T78397

Ref D12680

1 files changed, 174 insertions, 2 deletions

diff --git a/source/blender/editors/uvedit/uvedit_islands.c b/source/blender/editors/uvedit/uvedit_islands.c
index 56bcbc63de1..2aa09d7e731 100644
--- a/source/blender/editors/uvedit/uvedit_islands.c
+++ b/source/blender/editors/uvedit/uvedit_islands.c
@@ -29,6 +29,7 @@
 
 #include "DNA_meshdata_types.h"
 #include "DNA_scene_types.h"
+#include "DNA_space_types.h"
 
 #include "BLI_boxpack_2d.h"
 #include "BLI_convexhull_2d.h"
@@ -38,6 +39,7 @@
 
 #include "BKE_customdata.h"
 #include "BKE_editmesh.h"
+#include "BKE_image.h"
 
 #include "DEG_depsgraph.h"
 
@@ -232,6 +234,99 @@ static void bm_face_array_uv_scale_y(BMFace **faces,
 /** \} */
 
 /* -------------------------------------------------------------------- */
+/** \name UDIM packing helper functions
+ * \{ */
+
+/* Returns true if UV coordinates lie on a valid tile in UDIM grid or tiled image. */
+bool uv_coords_isect_udim(const Image *image, const int udim_grid[2], float coords[2])
+{
+  const float coords_floor[2] = {floorf(coords[0]), floorf(coords[1])};
+  const bool is_tiled_image = image && (image->source == IMA_SRC_TILED);
+
+  if (coords[0] < udim_grid[0] && coords[0] > 0 && coords[1] < udim_grid[1] && coords[1] > 0) {
+    return true;
+  }
+  /* Check if selection lies on a valid UDIM image tile. */
+  else if (is_tiled_image) {
+    LISTBASE_FOREACH (const ImageTile *, tile, &image->tiles) {
+      const int tile_index = tile->tile_number - 1001;
+      const int target_x = (tile_index % 10);
+      const int target_y = (tile_index / 10);
+      if (coords_floor[0] == target_x && coords_floor[1] == target_y) {
+        return true;
+      }
+    }
+  }
+  /* Probably not required since UDIM grid checks for 1001. */
+  else if (image && !is_tiled_image) {
+    if (is_zero_v2(coords_floor)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+/**
+ * Calculates distance to nearest UDIM image tile in UV space and its UDIM tile number.
+ */
+static float uv_nearest_image_tile_distance(const Image *image,
+                                            float coords[2],
+                                            float nearest_tile_co[2])
+{
+  int nearest_image_tile_index = BKE_image_find_nearest_tile(image, coords);
+  if (nearest_image_tile_index == -1) {
+    nearest_image_tile_index = 1001;
+  }
+
+  nearest_tile_co[0] = (nearest_image_tile_index - 1001) % 10;
+  nearest_tile_co[1] = (nearest_image_tile_index - 1001) / 10;
+  /* Add 0.5 to get tile center coordinates. */
+  float nearest_tile_center_co[2] = {nearest_tile_co[0], nearest_tile_co[1]};
+  add_v2_fl(nearest_tile_center_co, 0.5f);
+
+  return len_squared_v2v2(coords, nearest_tile_center_co);
+}
+
+/**
+ * Calculates distance to nearest UDIM grid tile in UV space and its UDIM tile number.
+ */
+static float uv_nearest_grid_tile_distance(const int udim_grid[2],
+                                           float coords[2],
+                                           float nearest_tile_co[2])
+{
+  const float coords_floor[2] = {floorf(coords[0]), floorf(coords[1])};
+
+  if (coords[0] > udim_grid[0]) {
+    nearest_tile_co[0] = udim_grid[0] - 1;
+  }
+  else if (coords[0] < 0) {
+    nearest_tile_co[0] = 0;
+  }
+  else {
+    nearest_tile_co[0] = coords_floor[0];
+  }
+
+  if (coords[1] > udim_grid[1]) {
+    nearest_tile_co[1] = udim_grid[1] - 1;
+  }
+  else if (coords[1] < 0) {
+    nearest_tile_co[1] = 0;
+  }
+  else {
+    nearest_tile_co[1] = coords_floor[1];
+  }
+
+  /* Add 0.5 to get tile center coordinates. */
+  float nearest_tile_center_co[2] = {nearest_tile_co[0], nearest_tile_co[1]};
+  add_v2_fl(nearest_tile_center_co, 0.5f);
+
+  return len_squared_v2v2(coords, nearest_tile_center_co);
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
 /** \name Calculate UV Islands
  *
  * \note Currently this is a private API/type, it could be made public.
@@ -357,8 +452,11 @@ static int bm_mesh_calc_uv_islands(const Scene *scene,
  * \{ */
 
 void ED_uvedit_pack_islands_multi(const Scene *scene,
+                                  const SpaceImage *sima,
                                   Object **objects,
                                   const uint objects_len,
+                                  const bool use_target_udim,
+                                  int target_udim,
                                   const struct UVPackIsland_Params *params)
 {
   /* Align to the Y axis, could make this configurable. */
@@ -407,8 +505,26 @@ void ED_uvedit_pack_islands_multi(const Scene *scene,
   BoxPack *boxarray = MEM_mallocN(sizeof(*boxarray) * island_list_len, __func__);
 
   int index;
+  /* Coordinates of bounding box containing all selected UVs. */
+  float selection_min_co[2], selection_max_co[2];
+  INIT_MINMAX2(selection_min_co, selection_max_co);
+
   LISTBASE_FOREACH_INDEX (struct FaceIsland *, island, &island_list, index) {
 
+    /* Skip calculation if using specified UDIM option. */
+    if (!use_target_udim) {
+      float bounds_min[2], bounds_max[2];
+      INIT_MINMAX2(bounds_min, bounds_max);
+      for (int i = 0; i < island->faces_len; i++) {
+        BMFace *f = island->faces[i];
+        BM_face_uv_minmax(f, bounds_min, bounds_max, island->cd_loop_uv_offset);
+      }
+
+      selection_min_co[0] = MIN2(bounds_min[0], selection_min_co[0]);
+      selection_min_co[1] = MIN2(bounds_min[1], selection_min_co[1]);
+      selection_max_co[0] = MAX2(bounds_max[0], selection_max_co[0]);
+      selection_max_co[1] = MAX2(bounds_max[1], selection_max_co[1]);
+    }
     if (params->rotate) {
       if (island->aspect_y != 1.0f) {
         bm_face_array_uv_scale_y(
@@ -441,6 +557,13 @@ void ED_uvedit_pack_islands_multi(const Scene *scene,
     }
   }
 
+  /* Center of bounding box containing all selected UVs. */
+  float selection_center[2];
+  if (!use_target_udim) {
+    selection_center[0] = (selection_min_co[0] + selection_max_co[0]) / 2.0f;
+    selection_center[1] = (selection_min_co[1] + selection_max_co[1]) / 2.0f;
+  }
+
   if (margin > 0.0f) {
     /* Logic matches behavior from #param_pack,
      * use area so multiply the margin by the area to give
@@ -464,6 +587,55 @@ void ED_uvedit_pack_islands_multi(const Scene *scene,
 
   const float scale[2] = {1.0f / boxarray_size[0], 1.0f / boxarray_size[1]};
 
+  /* Tile offset. */
+  float base_offset[2] = {0.0f, 0.0f};
+
+  /* CASE: Active/specified(smart uv project) UDIM. */
+  if (use_target_udim) {
+    /* Calculate offset based on specified_tile_index. */
+    base_offset[0] = (target_udim - 1001) % 10;
+    base_offset[1] = (target_udim - 1001) / 10;
+  }
+
+  /* CASE: Closest UDIM. */
+  else {
+    const Image *image;
+    int udim_grid[2] = {1, 1};
+    /* To handle cases where `sima == NULL` - Smart UV project in 3D viewport. */
+    if (sima != NULL) {
+      image = sima->image;
+      udim_grid[0] = sima->tile_grid_shape[0];
+      udim_grid[1] = sima->tile_grid_shape[1];
+    }
+
+    /* Check if selection lies on a valid UDIM grid tile. */
+    bool is_valid_udim = uv_coords_isect_udim(image, udim_grid, selection_center);
+    if (is_valid_udim) {
+      base_offset[0] = floorf(selection_center[0]);
+      base_offset[1] = floorf(selection_center[1]);
+    }
+    /* If selection doesn't lie on any UDIM then find the closest UDIM grid or image tile. */
+    else {
+      float nearest_image_tile_co[2] = {FLT_MAX, FLT_MAX};
+      float nearest_image_tile_dist = FLT_MAX, nearest_grid_tile_dist = FLT_MAX;
+      if (image) {
+        nearest_image_tile_dist = uv_nearest_image_tile_distance(
+            image, selection_center, nearest_image_tile_co);
+      }
+
+      float nearest_grid_tile_co[2] = {0.0f, 0.0f};
+      nearest_grid_tile_dist = uv_nearest_grid_tile_distance(
+          udim_grid, selection_center, nearest_grid_tile_co);
+
+      base_offset[0] = (nearest_image_tile_dist < nearest_grid_tile_dist) ?
+                           nearest_image_tile_co[0] :
+                           nearest_grid_tile_co[0];
+      base_offset[1] = (nearest_image_tile_dist < nearest_grid_tile_dist) ?
+                           nearest_image_tile_co[1] :
+                           nearest_grid_tile_co[1];
+    }
+  }
+
   for (int i = 0; i < island_list_len; i++) {
     struct FaceIsland *island = island_array[boxarray[i].index];
     const float pivot[2] = {
@@ -471,8 +643,8 @@ void ED_uvedit_pack_islands_multi(const Scene *scene,
         island->bounds_rect.ymin,
     };
     const float offset[2] = {
-        (boxarray[i].x * scale[0]) - island->bounds_rect.xmin,
-        (boxarray[i].y * scale[1]) - island->bounds_rect.ymin,
+        (boxarray[i].x * scale[0]) - island->bounds_rect.xmin + base_offset[0],
+        (boxarray[i].y * scale[1]) - island->bounds_rect.ymin + base_offset[1],
     };
     for (int j = 0; j < island->faces_len; j++) {
       BMFace *efa = island->faces[j];