@@ -98,1 +98,4 @@
 
+template<typename T, typename IndexT>
+inline void scatter(const VArray<T> &src,
+                    const Span<IndexT> indices,

@@ -1148,0 +1180,4 @@
+    grease_pencil_result.attributes_for_write().remove_anonymous();
+
+    /* Get the original material pointers from the result geometry. */
+    VectorSet<Material *> all_result_materials;

@@ -1148,0 +1184,4 @@
+    for (Material *eval_material :
+         Span{grease_pencil_result.material_array, grease_pencil_result.material_array_num})
+    {
+      BLI_assert(eval_material->id.orig_id != nullptr);

@@ -1148,0 +1192,4 @@
+    for (const int mat_i : IndexRange(grease_pencil_orig.material_array_num)) {
+      Material *material = grease_pencil_orig.material_array[mat_i];
+      const int map_index = all_result_materials.index_of_try(material);
+      BLI_assert(map_index != -1);

@@ -1148,0 +1205,4 @@
+      Drawing *drawing_eval = grease_pencil_result.get_drawing_at(*layer_eval, eval_frame);
+      if (drawing_eval) {
+        /* Anonymous attributes shouldn't be available on original geometry. */
+        drawing_eval->strokes_for_write().attributes_for_write().remove_anonymous();

@@ -1148,0 +1152,4 @@
+    if (mti->modify_geometry_set == nullptr) {
+      return false;
+    }
+    GreasePencil &grease_pencil_orig = *static_cast<GreasePencil *>(ob->data);

@@ -1148,0 +1263,4 @@
+      bke::MutableAttributeAccessor attributes =
+          drawing.strokes_for_write().attributes_for_write();
+      bke::SpanAttributeWriter<int> material_indices =
+          attributes.lookup_or_add_for_write_span<int>("material_index", bke::AttrDomain::Curve);

@@ -1148,0 +1273,4 @@
+    }
+
+    /* Copy layer attributes from the result to the original. */
+    bke::scatter_attributes(grease_pencil_result.attributes(),

@@ -988,0 +1129,4 @@
+    if (meta_data.data_type == CD_PROP_STRING) {
+      return true;
+    }
+    const GAttributeReader src = src_attributes.lookup(id, AttrDomain::Layer);

@@ -988,0 +1139,4 @@
+      using T = decltype(dummy);
+      array_utils::scatter(
+          src.varray.typed<T>(), eval_to_orig_layer_indices_map.as_span(), dst.span.typed<T>());
+      src.varray.type().default_construct_indices(dst.span.data(), unmapped_original_layers);

@@ -988,0 +1089,4 @@
+  for (Material *eval_material :
+       Span{grease_pencil_result.material_array, grease_pencil_result.material_array_num})
+  {
+    BLI_assert(eval_material->id.orig_id != nullptr);

@@ -988,0 +1098,4 @@
+  for (const int mat_i : IndexRange(grease_pencil_orig.material_array_num)) {
+    Material *material = grease_pencil_orig.material_array[mat_i];
+    const int map_index = original_materials.index_of_try(material);
+    BLI_assert(map_index != -1);

@@ -988,0 +1027,4 @@
+  for (const int layer_eval_i : grease_pencil_result.layers().index_range()) {
+    const Layer *layer_eval = grease_pencil_result.layer(layer_eval_i);
+    /* Check if the original geometry has a layer with the same name. */
+    TreeNode *node_orig = grease_pencil_orig.find_node_by_name(layer_eval->name());

@@ -988,0 +1060,4 @@
+      drawing_eval->strokes_for_write().attributes_for_write().remove_anonymous();
+    }
+    Drawing *drawing_orig = grease_pencil_orig.get_drawing_at(*layer_orig, eval_frame);
+    if (drawing_orig && drawing_eval) {

@@ -988,0 +1089,4 @@
+  for (Material *eval_material :
+       Span{grease_pencil_result.material_array, grease_pencil_result.material_array_num})
+  {
+    if (eval_material->id.orig_id != nullptr) {

@@ -988,0 +1095,4 @@
+  }
+
+  /* Build material indices mapping. */
+  Array<int> material_indices_map(grease_pencil_orig.material_array_num);