[Bf-blender-cvs] [8b3b353cafd] soc-2021-uv-editor-improvements-edge-selection: Fix: Prevent deselection of surrounding UV faces

[Siddhartha Jejurkar]

Commit: 8b3b353cafd151fc6236fe8fab417fd446d5ec03
Author: Siddhartha Jejurkar
Date:   Thu Jul 29 20:02:29 2021 +0530
Branches: soc-2021-uv-editor-improvements-edge-selection
https://developer.blender.org/rB8b3b353cafd151fc6236fe8fab417fd446d5ec03

Fix: Prevent deselection of surrounding UV faces

With face + sticky loc/vertex mode, trying to deselect UV faces would
sometimes result in surrounding UV faces being deselected as well. This
commit fixes that allowing conditional deselection of shared UV
vertices based on the selection state of surrounding UV faces.

===================================================================

M	source/blender/editors/uvedit/uvedit_select.c

===================================================================

diff --git a/source/blender/editors/uvedit/uvedit_select.c b/source/blender/editors/uvedit/uvedit_select.c
index aac9b8a419d..fe505f865b6 100644
--- a/source/blender/editors/uvedit/uvedit_select.c
+++ b/source/blender/editors/uvedit/uvedit_select.c
@@ -282,19 +282,53 @@ void uvedit_face_select_set_with_sticky(const SpaceImage *sima,
     case SI_STICKY_LOC:
     case SI_STICKY_VERTEX:
     default: {
-      /* Sticky location and vertex modes. */
-      /* Fallback, in case sima->sticky is invalid */
-      BMLoop *l_iter, *l_first;
-      l_iter = l_first = BM_FACE_FIRST_LOOP(efa);
-      do {
-        uvedit_edge_select_shared_location(
-            scene, em, l_iter, select, false, do_history, cd_loop_uv_offset);
-
-        uvedit_uv_select_shared_location(
-            scene, em, l_iter, select, false, do_history, cd_loop_uv_offset);
-        uvedit_uv_select_shared_location(
-            scene, em, l_iter->next, select, false, do_history, cd_loop_uv_offset);
-      } while ((l_iter = l_iter->next) != l_first);
+      if (uvedit_face_visible_test(scene, efa)) {
+        /* Sticky location and vertex modes. */
+        /* Fallback, in case sima->sticky is invalid */
+        BMLoop *l_iter, *l_first;
+        l_iter = l_first = BM_FACE_FIRST_LOOP(efa);
+        do {
+          MLoopUV *luv = BM_ELEM_CD_GET_VOID_P(l_iter, cd_loop_uv_offset);
+          if (select) {
+            /* Set selection flag for the internal edges of the face that is being selected */
+            luv->flag |= MLOOPUV_EDGESEL;
+            /* Select all shared vertices */
+            uvedit_uv_select_shared_location(
+                scene, em, l_iter, select, false, do_history, cd_loop_uv_offset);
+          }
+          else {
+            luv->flag &= ~MLOOPUV_EDGESEL;
+
+            bool do_vert_deselect = true;
+            BMEdge *e_first = l_iter->e, *e_iter;
+            e_iter = e_first;
+            do {
+              /* If any surrounding UV face is selected then don't deselect the shared UV vertices
+               * Deselcting the shared UV vertices could deselect the surrounding UV faces as
+               * well*/
+              BMLoop *l_radial_iter = e_iter->l;
+              do {
+                MLoopUV *luv_radial_other = BM_ELEM_CD_GET_VOID_P(l_radial_iter,
+                                                                  cd_loop_uv_offset);
+                if ((l_radial_iter->f != l_iter->f) &&
+                    uvedit_face_select_test(scene, l_radial_iter->f, cd_loop_uv_offset) &&
+                    equals_v2v2(luv->uv, luv_radial_other->uv)) {
+                  do_vert_deselect = false;
+                  break;
+                }
+              } while ((l_radial_iter = l_radial_iter->radial_next) != e_iter->l);
+              if (!do_vert_deselect) {
+                break;
+              }
+            } while ((e_iter = BM_DISK_EDGE_NEXT(e_iter, l_iter->v)) != e_first);
+
+            if (do_vert_deselect) {
+              uvedit_uv_select_shared_location(
+                  scene, em, l_iter, select, false, do_history, cd_loop_uv_offset);
+            }
+          }
+        } while ((l_iter = l_iter->next) != l_first);
+      }
       break;
     }
   }
@@ -438,10 +472,10 @@ void uvedit_edge_select_set_with_sticky(const struct SpaceImage *sima,
       uvedit_edge_select_shared_location(
           scene, em, l, select, false, do_history, cd_loop_uv_offset);
 
-      /* NOTE: This is a case where we deviate from the logic of: "EDGE SELECTION MODE SHOULD
-       * IMPLY ONLY EDGES MUST BE SELECTED".
-       * The UV vertex selections done below are to avoid the cases of edge selections breaking
-       * away (/become separate entities) from the vertices/edges they were connected to */
+      /* NOTE (Design tradeoff): This is a case where we deviate from the logic of: "EDGE
+       * SELECTION MODE SHOULD IMPLY ONLY EDGES MUST BE SELECTED". The UV vertex selections done
+       * below are to avoid the cases of edge selections breaking away (/become separate
+       * entities) from the vertices/edges they were connected to */
       uvedit_uv_select_shared_location(scene, em, l, select, false, do_history, cd_loop_uv_offset);
       uvedit_uv_select_shared_location(
           scene, em, l->next, select, false, do_history, cd_loop_uv_offset);
@@ -2980,7 +3014,7 @@ static void uv_select_flush_from_tag_sticky_loc_internal(Scene *scene,
 /**
  * Flush the selection from face tags based on sticky and selection modes.
  *
- * needed because settings the selection a face is done in a number of places but it also
+ * needed because setting the selection of a face is done in a number of places but it also
  * needs to respect the sticky modes for the UV verts, so dealing with the sticky modes
  * is best done in a separate function.
  *
@@ -3063,11 +3097,11 @@ static void uv_select_flush_from_tag_face(SpaceImage *sima,
 /**
  * Flush the selection from loop tags based on sticky and selection modes.
  *
- * needed because settings the selection a face is done in a number of places but it also needs
+ * needed because setting the selection of a face is done in a number of places but it also needs
  * to respect the sticky modes for the UV verts, so dealing with the sticky modes is best done
  * in a separate function.
  *
- * \note This function is very similar to #uv_select_flush_from_tag_loop,
+ * \note This function is very similar to #uv_select_flush_from_tag_face,
  * be sure to update both upon changing.
  */
 static void uv_select_flush_from_tag_loop(SpaceImage *sima,