Fix T91923: Save/Apply as Shape Key ignores shape keys

Support virtual modifiers when using applying the modifier as a shape.

3 files changed, 51 insertions, 10 deletions

diff --git a/source/blender/blenkernel/BKE_mesh.h b/source/blender/blenkernel/BKE_mesh.h
index f44d35c62a3..be9b84ccd62 100644
--- a/source/blender/blenkernel/BKE_mesh.h
+++ b/source/blender/blenkernel/BKE_mesh.h
@@ -209,6 +209,7 @@ struct Mesh *BKE_mesh_create_derived_for_modifier(struct Depsgraph *depsgraph,
                                                   struct Scene *scene,
                                                   struct Object *ob_eval,
                                                   struct ModifierData *md_eval,
+                                                  const bool use_virtual_modifiers,
                                                   const bool build_shapekey_layers);
 
 /* Copies a nomain-Mesh into an existing Mesh. */
diff --git a/source/blender/blenkernel/intern/mesh_convert.cc b/source/blender/blenkernel/intern/mesh_convert.cc
index adfbe4b8c94..b8fcc10be44 100644
--- a/source/blender/blenkernel/intern/mesh_convert.cc
+++ b/source/blender/blenkernel/intern/mesh_convert.cc
@@ -1277,10 +1277,16 @@ static void add_shapekey_layers(Mesh *mesh_dest, Mesh *mesh_src)
   }
 }
 
+/**
+ * \param use_virtual_modifiers: When enabled calculate virtual-modifiers before applying `md_eval`
+ * support this since virtual-modieirs are not modifiers from auser perspective,
+ * allowing shape keys to be included with the modifier being applied, see: T91923.
+ */
 Mesh *BKE_mesh_create_derived_for_modifier(struct Depsgraph *depsgraph,
                                            Scene *scene,
                                            Object *ob_eval,
                                            ModifierData *md_eval,
+                                           const bool use_virtual_modifiers,
                                            const bool build_shapekey_layers)
 {
   Mesh *me = ob_eval->runtime.data_orig ? (Mesh *)ob_eval->runtime.data_orig :
@@ -1303,22 +1309,49 @@ Mesh *BKE_mesh_create_derived_for_modifier(struct Depsgraph *depsgraph,
     BKE_keyblock_convert_to_mesh(kb, me);
   }
 
-  if (mti->type == eModifierTypeType_OnlyDeform) {
-    int numVerts;
-    float(*deformedVerts)[3] = BKE_mesh_vert_coords_alloc(me, &numVerts);
+  Mesh *mesh_temp = (Mesh *)BKE_id_copy_ex(nullptr, &me->id, nullptr, LIB_ID_COPY_LOCALIZE);
+  int numVerts = 0;
+  float(*deformedVerts)[3] = nullptr;
+
+  if (use_virtual_modifiers) {
+    VirtualModifierData virtualModifierData;
+    for (ModifierData *md_eval_virt =
+             BKE_modifiers_get_virtual_modifierlist(ob_eval, &virtualModifierData);
+         md_eval_virt && (md_eval_virt != ob_eval->modifiers.first);
+         md_eval_virt = md_eval_virt->next) {
+      if (!BKE_modifier_is_enabled(scene, md_eval_virt, eModifierMode_Realtime)) {
+        continue;
+      }
+      /* All virtual modifiers are deform modifiers. */
+      const ModifierTypeInfo *mti_virt = BKE_modifier_get_info((ModifierType)md_eval_virt->type);
+      BLI_assert(mti_virt->type == eModifierTypeType_OnlyDeform);
+      if (mti_virt->type != eModifierTypeType_OnlyDeform) {
+        continue;
+      }
+
+      if (deformedVerts == nullptr) {
+        deformedVerts = BKE_mesh_vert_coords_alloc(me, &numVerts);
+      }
+      mti_virt->deformVerts(md_eval_virt, &mectx, mesh_temp, deformedVerts, numVerts);
+    }
+  }
 
-    result = (Mesh *)BKE_id_copy_ex(nullptr, &me->id, nullptr, LIB_ID_COPY_LOCALIZE);
+  if (mti->type == eModifierTypeType_OnlyDeform) {
+    if (deformedVerts == nullptr) {
+      deformedVerts = BKE_mesh_vert_coords_alloc(me, &numVerts);
+    }
+    result = mesh_temp;
     mti->deformVerts(md_eval, &mectx, result, deformedVerts, numVerts);
     BKE_mesh_vert_coords_apply(result, deformedVerts);
 
     if (build_shapekey_layers) {
       add_shapekey_layers(result, me);
     }
-
-    MEM_freeN(deformedVerts);
   }
   else {
-    Mesh *mesh_temp = (Mesh *)BKE_id_copy_ex(nullptr, &me->id, nullptr, LIB_ID_COPY_LOCALIZE);
+    if (deformedVerts != nullptr) {
+      BKE_mesh_vert_coords_apply(mesh_temp, deformedVerts);
+    }
 
     if (build_shapekey_layers) {
       add_shapekey_layers(mesh_temp, me);
@@ -1332,6 +1365,10 @@ Mesh *BKE_mesh_create_derived_for_modifier(struct Depsgraph *depsgraph,
     }
   }
 
+  if (deformedVerts != nullptr) {
+    MEM_freeN(deformedVerts);
+  }
+
   return result;
 }
 
diff --git a/source/blender/editors/object/object_modifier.c b/source/blender/editors/object/object_modifier.c
index efe19785f31..21b978268d9 100644
--- a/source/blender/editors/object/object_modifier.c
+++ b/source/blender/editors/object/object_modifier.c
@@ -666,12 +666,13 @@ bool ED_object_modifier_convert(ReportList *UNUSED(reports),
 static Mesh *modifier_apply_create_mesh_for_modifier(Depsgraph *depsgraph,
                                                      Object *object,
                                                      ModifierData *md_eval,
+                                                     bool use_virtual_modifiers,
                                                      bool build_shapekey_layers)
 {
   Scene *scene_eval = DEG_get_evaluated_scene(depsgraph);
   Object *object_eval = DEG_get_evaluated_object(depsgraph, object);
   Mesh *mesh_applied = BKE_mesh_create_derived_for_modifier(
-      depsgraph, scene_eval, object_eval, md_eval, build_shapekey_layers);
+      depsgraph, scene_eval, object_eval, md_eval, use_virtual_modifiers, build_shapekey_layers);
   return mesh_applied;
 }
 
@@ -708,7 +709,8 @@ static bool modifier_apply_shape(Main *bmain,
       return false;
     }
 
-    Mesh *mesh_applied = modifier_apply_create_mesh_for_modifier(depsgraph, ob, md_eval, false);
+    Mesh *mesh_applied = modifier_apply_create_mesh_for_modifier(
+        depsgraph, ob, md_eval, true, false);
     if (!mesh_applied) {
       BKE_report(reports, RPT_ERROR, "Modifier is disabled or returned error, skipping apply");
       return false;
@@ -767,7 +769,8 @@ static bool modifier_apply_obdata(
       }
     }
     else {
-      Mesh *mesh_applied = modifier_apply_create_mesh_for_modifier(depsgraph, ob, md_eval, true);
+      Mesh *mesh_applied = modifier_apply_create_mesh_for_modifier(
+          depsgraph, ob, md_eval, true, true);
       if (!mesh_applied) {
         BKE_report(reports, RPT_ERROR, "Modifier returned error, skipping apply");
         return false;