3 files changed, 53 insertions, 25 deletions

diff --git a/source/blender/blenkernel/BKE_multires.h b/source/blender/blenkernel/BKE_multires.h
index cccb5547603..a7a5e7b8bd5 100644
--- a/source/blender/blenkernel/BKE_multires.h
+++ b/source/blender/blenkernel/BKE_multires.h
@@ -96,11 +96,12 @@ struct Mesh *BKE_multires_create_mesh(struct Depsgraph *depsgraph,
                                       struct Object *object,
                                       struct MultiresModifierData *mmd);
 
-/* Creates mesh with all deform modifiers leading the multires one applied.
+/* Get coordinates of a deformed base mesh which is an ionput to the given multires modifier.
  * NOTE: The modifiers will be re-evaluated. */
-struct Mesh *BKE_multires_create_deformed_base_mesh(struct Depsgraph *depsgraph,
-                                                    struct Object *object,
-                                                    struct MultiresModifierData *mmd);
+float (*BKE_multires_create_deformed_base_mesh_vert_coords(struct Depsgraph *depsgraph,
+                                                           struct Object *object,
+                                                           struct MultiresModifierData *mmd,
+                                                           int *r_num_deformed_verts))[3];
 
 void multiresModifier_del_levels(struct MultiresModifierData *mmd,
                                  struct Scene *scene,
diff --git a/source/blender/blenkernel/intern/multires.c b/source/blender/blenkernel/intern/multires.c
index fd91f80b047..234273b5158 100644
--- a/source/blender/blenkernel/intern/multires.c
+++ b/source/blender/blenkernel/intern/multires.c
@@ -293,23 +293,55 @@ Mesh *BKE_multires_create_mesh(struct Depsgraph *depsgraph,
   return result;
 }
 
-Mesh *BKE_multires_create_deformed_base_mesh(struct Depsgraph *depsgraph,
-                                             Object *object,
-                                             MultiresModifierData *mmd)
+float (*BKE_multires_create_deformed_base_mesh_vert_coords(struct Depsgraph *depsgraph,
+                                                           struct Object *object,
+                                                           struct MultiresModifierData *mmd,
+                                                           int *r_num_deformed_verts))[3]
 {
   Scene *scene_eval = DEG_get_evaluated_scene(depsgraph);
   Object *object_eval = DEG_get_evaluated_object(depsgraph, object);
 
-  const int mmd_index = BLI_findindex(&object->modifiers, &mmd->modifier);
-  BLI_assert(mmd_index != -1);
-
   Object object_for_eval = *object_eval;
   object_for_eval.data = object->data;
 
-  Mesh *base_mesh = mesh_create_eval_final_view_index(
-      depsgraph, scene_eval, object, &CD_MASK_BAREMESH, mmd_index - 1);
+  const bool use_render = (DEG_get_mode(depsgraph) == DAG_EVAL_RENDER);
+  ModifierEvalContext mesh_eval_context = {depsgraph, &object_for_eval, 0};
+  if (use_render) {
+    mesh_eval_context.flag |= MOD_APPLY_RENDER;
+  }
+  const int required_mode = use_render ? eModifierMode_Render : eModifierMode_Realtime;
+
+  VirtualModifierData virtual_modifier_data;
+  ModifierData *first_md = modifiers_getVirtualModifierList(&object_for_eval,
+                                                            &virtual_modifier_data);
+
+  Mesh *base_mesh = object->data;
+
+  int num_deformed_verts;
+  float(*deformed_verts)[3] = BKE_mesh_vert_coords_alloc(base_mesh, &num_deformed_verts);
+
+  for (ModifierData *md = first_md; md != NULL; md = md->next) {
+    const ModifierTypeInfo *mti = modifierType_getInfo(md->type);
+
+    if (md == &mmd->modifier) {
+      break;
+    }
+
+    if (!modifier_isEnabled(scene_eval, md, required_mode)) {
+      continue;
+    }
 
-  return base_mesh;
+    if (mti->type != eModifierTypeType_OnlyDeform) {
+      break;
+    }
+
+    modwrap_deformVerts(md, &mesh_eval_context, base_mesh, deformed_verts, num_deformed_verts);
+  }
+
+  if (r_num_deformed_verts != NULL) {
+    *r_num_deformed_verts = num_deformed_verts;
+  }
+  return deformed_verts;
 }
 
 MultiresModifierData *find_multires_modifier_before(Scene *scene, ModifierData *lastmd)
diff --git a/source/blender/blenkernel/intern/multires_reshape_apply_base.c b/source/blender/blenkernel/intern/multires_reshape_apply_base.c
index 958fb60bbdc..62418150ff1 100644
--- a/source/blender/blenkernel/intern/multires_reshape_apply_base.c
+++ b/source/blender/blenkernel/intern/multires_reshape_apply_base.c
@@ -189,16 +189,11 @@ void multires_reshape_apply_base_refine_from_deform(MultiresReshapeContext *resh
   BLI_assert(object != NULL);
   BLI_assert(mmd != NULL);
 
-  /* If there are no modifiers prior to the multires can use base mesh as it have all the updated
-   * vertices already. */
-  if (mmd->modifier.prev == NULL) {
-    BKE_subdiv_eval_update_from_mesh(reshape_context->subdiv, reshape_context->base_mesh, NULL);
-  }
-  else {
-    /* TODO(sergey): Possible optimization is to only evaluate new verticies positions without
-     * construction of the entire mesh. */
-    Mesh *deformed_base_mesh = BKE_multires_create_deformed_base_mesh(depsgraph, object, mmd);
-    BKE_subdiv_eval_update_from_mesh(reshape_context->subdiv, deformed_base_mesh, NULL);
-    BKE_id_free(NULL, deformed_base_mesh);
-  }
+  float(*deformed_verts)[3] = BKE_multires_create_deformed_base_mesh_vert_coords(
+      depsgraph, object, mmd, NULL);
+
+  BKE_subdiv_eval_update_from_mesh(
+      reshape_context->subdiv, reshape_context->base_mesh, deformed_verts);
+
+  MEM_freeN(deformed_verts);
 }