Transform: use a threshold for UV snapping

Unlike 3Dview snapping, UV snapping is always done to the UV closest to
the mouse cursor, no matter the distance.

From the user's point of view, this appears to be an inconsistency (See
{T93538}).

Therefore, set a minimum distance for snapping and, as in 3D View and
highlight the snap with a drawing of a circle.

Release Note: https://wiki.blender.org/wiki/Reference/Release_Notes/3.3/Modeling

Reviewed By: #uv_editing, campbellbarton

Maniphest Tasks: T93538

Differential Revision: https://developer.blender.org/D13873

3 files changed, 72 insertions, 31 deletions

diff --git a/source/blender/editors/include/ED_uvedit.h b/source/blender/editors/include/ED_uvedit.h
index 4c01c75e06c..54d36f44f82 100644
--- a/source/blender/editors/include/ED_uvedit.h
+++ b/source/blender/editors/include/ED_uvedit.h
@@ -24,6 +24,7 @@ struct Object;
 struct Scene;
 struct SpaceImage;
 struct ToolSettings;
+struct View2D;
 struct ViewLayer;
 struct bContext;
 struct bNode;
@@ -242,15 +243,12 @@ void uvedit_deselect_flush(const struct Scene *scene, struct BMEditMesh *em);
  */
 void uvedit_select_flush(const struct Scene *scene, struct BMEditMesh *em);
 
-bool ED_uvedit_nearest_uv(const struct Scene *scene,
-                          struct Object *obedit,
-                          const float co[2],
-                          float *dist_sq,
-                          float r_uv[2]);
-bool ED_uvedit_nearest_uv_multi(const struct Scene *scene,
+bool ED_uvedit_nearest_uv_multi(const struct View2D *v2d,
+                                const struct Scene *scene,
                                 struct Object **objects,
                                 uint objects_len,
-                                const float co[2],
+                                const int mval[2],
+                                const bool ignore_selected,
                                 float *dist_sq,
                                 float r_uv[2]);
 
diff --git a/source/blender/editors/transform/transform_snap.c b/source/blender/editors/transform/transform_snap.c
index afad4df2c88..e119b264ae7 100644
--- a/source/blender/editors/transform/transform_snap.c
+++ b/source/blender/editors/transform/transform_snap.c
@@ -15,6 +15,7 @@
 #include "BLI_math.h"
 
 #include "GPU_immediate.h"
+#include "GPU_matrix.h"
 #include "GPU_state.h"
 
 #include "BKE_context.h"
@@ -25,6 +26,7 @@
 
 #include "RNA_access.h"
 
+#include "WM_api.h"
 #include "WM_types.h"
 
 #include "ED_gizmo_library.h"
@@ -173,20 +175,20 @@ void drawSnapping(const struct bContext *C, TransInfo *t)
     return;
   }
 
-  UI_GetThemeColor3ubv(TH_TRANSFORM, col);
-  col[3] = 128;
-
-  UI_GetThemeColor3ubv(TH_SELECT, selectedCol);
-  selectedCol[3] = 128;
-
-  UI_GetThemeColor3ubv(TH_ACTIVE, activeCol);
-  activeCol[3] = 192;
-
   if (t->spacetype == SPACE_VIEW3D) {
     bool draw_target = (t->tsnap.status & TARGET_INIT) &&
                        (t->tsnap.mode & SCE_SNAP_MODE_EDGE_PERPENDICULAR);
 
     if (draw_target || validSnap(t)) {
+      UI_GetThemeColor3ubv(TH_TRANSFORM, col);
+      col[3] = 128;
+
+      UI_GetThemeColor3ubv(TH_SELECT, selectedCol);
+      selectedCol[3] = 128;
+
+      UI_GetThemeColor3ubv(TH_ACTIVE, activeCol);
+      activeCol[3] = 192;
+
       const float *loc_cur = NULL;
       const float *loc_prev = NULL;
       const float *normal = NULL;
@@ -240,8 +242,26 @@ void drawSnapping(const struct bContext *C, TransInfo *t)
   }
   else if (t->spacetype == SPACE_IMAGE) {
     if (validSnap(t)) {
-      /* This will not draw, and I'm nor sure why - campbell */
-      /* TODO: see 2.7x for non-working code */
+      uint pos = GPU_vertformat_attr_add(
+          immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
+
+      float x, y;
+      const float snap_point[2] = {
+          t->tsnap.snapPoint[0] / t->aspect[0],
+          t->tsnap.snapPoint[1] / t->aspect[1],
+      };
+      UI_view2d_view_to_region_fl(&t->region->v2d, UNPACK2(snap_point), &x, &y);
+      float radius = 2.5f * UI_GetThemeValuef(TH_VERTEX_SIZE) * U.pixelsize;
+
+      GPU_matrix_push_projection();
+      wmOrtho2_region_pixelspace(t->region);
+
+      immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
+      immUniformColor3ub(255, 255, 255);
+      imm_draw_circle_wire_2d(pos, x, y, radius, 8);
+      immUnbindProgram();
+
+      GPU_matrix_pop_projection();
     }
   }
   else if (t->spacetype == SPACE_NODE) {
@@ -990,17 +1010,19 @@ static void snap_calc_uv_fn(TransInfo *t, float *UNUSED(vec))
 {
   BLI_assert(t->spacetype == SPACE_IMAGE);
   if (t->tsnap.mode & SCE_SNAP_MODE_VERTEX) {
-    float co[2];
-
-    UI_view2d_region_to_view(&t->region->v2d, t->mval[0], t->mval[1], &co[0], &co[1]);
-
     uint objects_len = 0;
     Object **objects = BKE_view_layer_array_from_objects_in_edit_mode_unique_data_with_uvs(
         t->view_layer, NULL, &objects_len);
 
-    float dist_sq = FLT_MAX;
-    if (ED_uvedit_nearest_uv_multi(
-            t->scene, objects, objects_len, co, &dist_sq, t->tsnap.snapPoint)) {
+    float dist_sq = square_f((float)SNAP_MIN_DISTANCE);
+    if (ED_uvedit_nearest_uv_multi(&t->region->v2d,
+                                   t->scene,
+                                   objects,
+                                   objects_len,
+                                   t->mval,
+                                   true,
+                                   &dist_sq,
+                                   t->tsnap.snapPoint)) {
       t->tsnap.snapPoint[0] *= t->aspect[0];
       t->tsnap.snapPoint[1] *= t->aspect[1];
 
diff --git a/source/blender/editors/uvedit/uvedit_select.c b/source/blender/editors/uvedit/uvedit_select.c
index 1287804d9ee..13dac431b57 100644
--- a/source/blender/editors/uvedit/uvedit_select.c
+++ b/source/blender/editors/uvedit/uvedit_select.c
@@ -1019,8 +1019,13 @@ bool uv_find_nearest_vert_multi(Scene *scene,
   return found;
 }
 
-bool ED_uvedit_nearest_uv(
-    const Scene *scene, Object *obedit, const float co[2], float *dist_sq, float r_uv[2])
+static bool uvedit_nearest_uv(const Scene *scene,
+                              Object *obedit,
+                              const float co[2],
+                              const float scale[2],
+                              const bool ignore_selected,
+                              float *dist_sq,
+                              float r_uv[2])
 {
   BMEditMesh *em = BKE_editmesh_from_object(obedit);
   BMIter iter;
@@ -1035,8 +1040,14 @@ bool ED_uvedit_nearest_uv(
     BMLoop *l_iter, *l_first;
     l_iter = l_first = BM_FACE_FIRST_LOOP(efa);
     do {
+      if (ignore_selected && uvedit_uv_select_test(scene, l_iter, cd_loop_uv_offset)) {
+        continue;
+      }
+
       const float *uv = ((const MLoopUV *)BM_ELEM_CD_GET_VOID_P(l_iter, cd_loop_uv_offset))->uv;
-      const float dist_test = len_squared_v2v2(co, uv);
+      float co_tmp[2];
+      mul_v2_v2v2(co_tmp, scale, uv);
+      const float dist_test = len_squared_v2v2(co, co_tmp);
       if (dist_best > dist_test) {
         dist_best = dist_test;
         uv_best = uv;
@@ -1052,17 +1063,27 @@ bool ED_uvedit_nearest_uv(
   return false;
 }
 
-bool ED_uvedit_nearest_uv_multi(const Scene *scene,
+bool ED_uvedit_nearest_uv_multi(const View2D *v2d,
+                                const Scene *scene,
                                 Object **objects,
                                 const uint objects_len,
-                                const float co[2],
+                                const int mval[2],
+                                const bool ignore_selected,
                                 float *dist_sq,
                                 float r_uv[2])
 {
   bool found = false;
+
+  float scale[2], offset[2];
+  UI_view2d_scale_get(v2d, &scale[0], &scale[1]);
+  UI_view2d_view_to_region_fl(v2d, 0.0f, 0.0f, &offset[0], &offset[1]);
+
+  float co[2];
+  sub_v2_v2v2(co, (float[2]){UNPACK2(mval)}, offset);
+
   for (uint ob_index = 0; ob_index < objects_len; ob_index++) {
     Object *obedit = objects[ob_index];
-    if (ED_uvedit_nearest_uv(scene, obedit, co, dist_sq, r_uv)) {
+    if (uvedit_nearest_uv(scene, obedit, co, scale, ignore_selected, dist_sq, r_uv)) {
       found = true;
     }
   }