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

1 files changed, 40 insertions, 18 deletions

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];