Fix assertion snapping to selected in mesh edit-mode

ED_transverts_create_from_obedit expected an evaluated object.

Add flag to request TX_VERT_USE_MAPLOC to be set, which avoids having to
calculate this data when it's not used as well as the requirement
that the input object be evaluated from the depsgraph.

3 files changed, 23 insertions, 11 deletions

diff --git a/source/blender/editors/include/ED_transverts.h b/source/blender/editors/include/ED_transverts.h
index cbcf28d53d5..dbf156d480f 100644
--- a/source/blender/editors/include/ED_transverts.h
+++ b/source/blender/editors/include/ED_transverts.h
@@ -28,6 +28,7 @@ extern "C" {
 #endif
 
 struct Object;
+struct bContext;
 
 typedef struct TransVert {
   float *loc;
@@ -42,10 +43,14 @@ typedef struct TransVertStore {
   int mode;
 } TransVertStore;
 
-void ED_transverts_create_from_obedit(TransVertStore *tvs, struct Object *obedit, int mode);
+/**
+ * \param obedit: When `mode` has the #TM_CALC_MAPLOC flag set, `obedit` must be evaluated,
+ * to access evaluated vertices.
+ */
+void ED_transverts_create_from_obedit(TransVertStore *tvs, const struct Object *obedit, int mode);
 void ED_transverts_update_obedit(TransVertStore *tvs, struct Object *obedit);
 void ED_transverts_free(TransVertStore *tvs);
-bool ED_transverts_check_obedit(Object *obedit);
+bool ED_transverts_check_obedit(const struct Object *obedit);
 bool ED_transverts_poll(struct bContext *C);
 
 /* currently only used for bmesh index values */
@@ -66,12 +71,16 @@ enum {
   TM_SKIP_HANDLES = (1 << 1),
   /** fill in normals when available */
   TM_CALC_NORMALS = (1 << 2),
+  /** Calculates #TransVert.maploc where possible. */
+  TM_CALC_MAPLOC = (1 << 2),
 };
 
 enum {
   /* SELECT == (1 << 0) */
+  /** Calculated when #TM_CALC_MAPLOC is set. */
   TX_VERT_USE_MAPLOC = (1 << 1),
-  TX_VERT_USE_NORMAL = (1 << 2), /* avoid nonzero check */
+  /** Calculated when #TM_CALC_NORMALS is set, avoid nonzero check. */
+  TX_VERT_USE_NORMAL = (1 << 2),
 };
 
 #ifdef __cplusplus
diff --git a/source/blender/editors/space_view3d/view3d_snap.c b/source/blender/editors/space_view3d/view3d_snap.c
index 53bd181f544..4334ede0a06 100644
--- a/source/blender/editors/space_view3d/view3d_snap.c
+++ b/source/blender/editors/space_view3d/view3d_snap.c
@@ -1033,7 +1033,7 @@ bool ED_view3d_minmax_verts(Object *obedit, float r_min[3], float r_max[3])
   }
 
   if (ED_transverts_check_obedit(obedit)) {
-    ED_transverts_create_from_obedit(&tvs, obedit, TM_ALL_JOINTS);
+    ED_transverts_create_from_obedit(&tvs, obedit, TM_ALL_JOINTS | TM_CALC_MAPLOC);
   }
 
   if (tvs.transverts_tot == 0) {
diff --git a/source/blender/editors/util/ed_transverts.c b/source/blender/editors/util/ed_transverts.c
index b8efbad1ad9..b9e90670a4d 100644
--- a/source/blender/editors/util/ed_transverts.c
+++ b/source/blender/editors/util/ed_transverts.c
@@ -195,12 +195,12 @@ static void set_mapped_co(void *vuserdata, int index, const float co[3], const f
   }
 }
 
-bool ED_transverts_check_obedit(Object *obedit)
+bool ED_transverts_check_obedit(const Object *obedit)
 {
   return (ELEM(obedit->type, OB_ARMATURE, OB_LATTICE, OB_MESH, OB_SURF, OB_CURVE, OB_MBALL));
 }
 
-void ED_transverts_create_from_obedit(TransVertStore *tvs, Object *obedit, const int mode)
+void ED_transverts_create_from_obedit(TransVertStore *tvs, const Object *obedit, const int mode)
 {
   Nurb *nu;
   BezTriple *bezt;
@@ -214,7 +214,7 @@ void ED_transverts_create_from_obedit(TransVertStore *tvs, Object *obedit, const
   tvs->transverts_tot = 0;
 
   if (obedit->type == OB_MESH) {
-    BMEditMesh *em = BKE_editmesh_from_object(obedit);
+    BMEditMesh *em = BKE_editmesh_from_object((Object *)obedit);
     BMesh *bm = em->bm;
     BMIter iter;
     void *userdata[2] = {em, NULL};
@@ -312,10 +312,13 @@ void ED_transverts_create_from_obedit(TransVertStore *tvs, Object *obedit, const
       userdata[1] = tvs->transverts;
     }
 
-    struct Mesh *editmesh_eval_cage = BKE_object_get_editmesh_eval_cage(obedit);
-    if (tvs->transverts && editmesh_eval_cage) {
-      BM_mesh_elem_table_ensure(bm, BM_VERT);
-      BKE_mesh_foreach_mapped_vert(editmesh_eval_cage, set_mapped_co, userdata, MESH_FOREACH_NOP);
+    if (mode & TM_CALC_MAPLOC) {
+      struct Mesh *editmesh_eval_cage = BKE_object_get_editmesh_eval_cage(obedit);
+      if (tvs->transverts && editmesh_eval_cage) {
+        BM_mesh_elem_table_ensure(bm, BM_VERT);
+        BKE_mesh_foreach_mapped_vert(
+            editmesh_eval_cage, set_mapped_co, userdata, MESH_FOREACH_NOP);
+      }
     }
   }
   else if (obedit->type == OB_ARMATURE) {