Fix T70163: Error painting with Subdivision at end of stack

Deformation of subdivision surface modifier was using wrong coordinates
for the coarse mesh: as the modifier flow goes the coordinates are to be
taken from the input array of coordinates.

5 files changed, 20 insertions, 9 deletions

diff --git a/source/blender/blenkernel/intern/multires_reshape.c b/source/blender/blenkernel/intern/multires_reshape.c
index 3257bc1b193..4e4a8831518 100644
--- a/source/blender/blenkernel/intern/multires_reshape.c
+++ b/source/blender/blenkernel/intern/multires_reshape.c
@@ -795,7 +795,7 @@ static Subdiv *multires_create_subdiv_for_reshape(struct Depsgraph *depsgraph,
   SubdivSettings subdiv_settings;
   BKE_multires_subdiv_settings_init(&subdiv_settings, mmd);
   Subdiv *subdiv = BKE_subdiv_new_from_mesh(&subdiv_settings, deformed_mesh);
-  if (!BKE_subdiv_eval_update_from_mesh(subdiv, deformed_mesh)) {
+  if (!BKE_subdiv_eval_update_from_mesh(subdiv, deformed_mesh, NULL)) {
     BKE_subdiv_free(subdiv);
     return NULL;
   }
diff --git a/source/blender/blenkernel/intern/subdiv_ccg.c b/source/blender/blenkernel/intern/subdiv_ccg.c
index 843e68108c3..471cca53900 100644
--- a/source/blender/blenkernel/intern/subdiv_ccg.c
+++ b/source/blender/blenkernel/intern/subdiv_ccg.c
@@ -591,7 +591,7 @@ Mesh *BKE_subdiv_to_ccg_mesh(Subdiv *subdiv,
 {
   /* Make sure evaluator is ready. */
   BKE_subdiv_stats_begin(&subdiv->stats, SUBDIV_STATS_SUBDIV_TO_CCG);
-  if (!BKE_subdiv_eval_update_from_mesh(subdiv, coarse_mesh)) {
+  if (!BKE_subdiv_eval_update_from_mesh(subdiv, coarse_mesh, NULL)) {
     if (coarse_mesh->totpoly) {
       return false;
     }
diff --git a/source/blender/blenkernel/intern/subdiv_deform.c b/source/blender/blenkernel/intern/subdiv_deform.c
index 5b9335a503e..9c7949e7bdb 100644
--- a/source/blender/blenkernel/intern/subdiv_deform.c
+++ b/source/blender/blenkernel/intern/subdiv_deform.c
@@ -195,7 +195,7 @@ void BKE_subdiv_deform_coarse_vertices(struct Subdiv *subdiv,
   /* Make sure evaluator is up to date with possible new topology, and that
    * is is refined for the new positions of coarse vertices.
    */
-  if (!BKE_subdiv_eval_update_from_mesh(subdiv, coarse_mesh)) {
+  if (!BKE_subdiv_eval_update_from_mesh(subdiv, coarse_mesh, vertex_cos)) {
     /* This could happen in two situations:
      * - OpenSubdiv is disabled.
      * - Something totally bad happened, and OpenSubdiv rejected our
diff --git a/source/blender/blenkernel/intern/subdiv_eval.c b/source/blender/blenkernel/intern/subdiv_eval.c
index 419371c7a4b..bf5e886dd22 100644
--- a/source/blender/blenkernel/intern/subdiv_eval.c
+++ b/source/blender/blenkernel/intern/subdiv_eval.c
@@ -61,7 +61,9 @@ bool BKE_subdiv_eval_begin(Subdiv *subdiv)
   return true;
 }
 
-static void set_coarse_positions(Subdiv *subdiv, const Mesh *mesh)
+static void set_coarse_positions(Subdiv *subdiv,
+                                 const Mesh *mesh,
+                                 const float (*coarse_vertex_cos)[3])
 {
   const MVert *mvert = mesh->mvert;
   const MLoop *mloop = mesh->mloop;
@@ -83,8 +85,15 @@ static void set_coarse_positions(Subdiv *subdiv, const Mesh *mesh)
     if (!BLI_BITMAP_TEST_BOOL(vertex_used_map, vertex_index)) {
       continue;
     }
-    const MVert *vertex = &mvert[vertex_index];
-    subdiv->evaluator->setCoarsePositions(subdiv->evaluator, vertex->co, manifold_veretx_index, 1);
+    const float *vertex_co;
+    if (coarse_vertex_cos != NULL) {
+      vertex_co = coarse_vertex_cos[vertex_index];
+    }
+    else {
+      const MVert *vertex = &mvert[vertex_index];
+      vertex_co = vertex->co;
+    }
+    subdiv->evaluator->setCoarsePositions(subdiv->evaluator, vertex_co, manifold_veretx_index, 1);
     manifold_veretx_index++;
   }
   MEM_freeN(vertex_used_map);
@@ -112,7 +121,9 @@ static void set_face_varying_data_from_uv(Subdiv *subdiv,
   }
 }
 
-bool BKE_subdiv_eval_update_from_mesh(Subdiv *subdiv, const Mesh *mesh)
+bool BKE_subdiv_eval_update_from_mesh(Subdiv *subdiv,
+                                      const Mesh *mesh,
+                                      const float (*coarse_vertex_cos)[3])
 {
   if (!BKE_subdiv_eval_begin(subdiv)) {
     return false;
@@ -123,7 +134,7 @@ bool BKE_subdiv_eval_update_from_mesh(Subdiv *subdiv, const Mesh *mesh)
     return false;
   }
   /* Set coordinates of base mesh vertices. */
-  set_coarse_positions(subdiv, mesh);
+  set_coarse_positions(subdiv, mesh, coarse_vertex_cos);
   /* Set face-varyign data to UV maps. */
   const int num_uv_layers = CustomData_number_of_layers(&mesh->ldata, CD_MLOOPUV);
   for (int layer_index = 0; layer_index < num_uv_layers; layer_index++) {
diff --git a/source/blender/blenkernel/intern/subdiv_mesh.c b/source/blender/blenkernel/intern/subdiv_mesh.c
index 57330575735..a30dde6284b 100644
--- a/source/blender/blenkernel/intern/subdiv_mesh.c
+++ b/source/blender/blenkernel/intern/subdiv_mesh.c
@@ -1166,7 +1166,7 @@ Mesh *BKE_subdiv_to_mesh(Subdiv *subdiv,
   /* Make sure evaluator is up to date with possible new topology, and that
    * is is refined for the new positions of coarse vertices.
    */
-  if (!BKE_subdiv_eval_update_from_mesh(subdiv, coarse_mesh)) {
+  if (!BKE_subdiv_eval_update_from_mesh(subdiv, coarse_mesh, NULL)) {
     /* This could happen in two situations:
      * - OpenSubdiv is disabled.
      * - Something totally bad happened, and OpenSubdiv rejected our