[Bf-blender-cvs] [4ae0da1bbc6] master: Geometry Nodes: Avoid mesh copy in some cases

[Hans Goudey]

Commit: 4ae0da1bbc61e5b712508646ef7b4bbea9014abf
Author: Hans Goudey
Date:   Mon Dec 19 14:24:49 2022 -0600
Branches: master
https://developer.blender.org/rB4ae0da1bbc61e5b712508646ef7b4bbea9014abf

Geometry Nodes: Avoid mesh copy in some cases

Accessing a mesh with write access can be costly if it is used
elsewhere at the same time because of copy-on-write. When always did
that at the end of the modifier calculation, but it's trivial to only
do that when we might need actually use the mesh to add original
index layers.

===================================================================

M	source/blender/modifiers/intern/MOD_nodes.cc

===================================================================

diff --git a/source/blender/modifiers/intern/MOD_nodes.cc b/source/blender/modifiers/intern/MOD_nodes.cc
index f5ede42b0ad..258971c3565 100644
--- a/source/blender/modifiers/intern/MOD_nodes.cc
+++ b/source/blender/modifiers/intern/MOD_nodes.cc
@@ -1282,29 +1282,29 @@ static void modifyGeometry(ModifierData *md,
   bool use_orig_index_verts = false;
   bool use_orig_index_edges = false;
   bool use_orig_index_polys = false;
-  if (geometry_set.has_mesh()) {
-    const Mesh &mesh = *geometry_set.get_mesh_for_read();
-    use_orig_index_verts = CustomData_has_layer(&mesh.vdata, CD_ORIGINDEX);
-    use_orig_index_edges = CustomData_has_layer(&mesh.edata, CD_ORIGINDEX);
-    use_orig_index_polys = CustomData_has_layer(&mesh.pdata, CD_ORIGINDEX);
+  if (const Mesh *mesh = geometry_set.get_mesh_for_read()) {
+    use_orig_index_verts = CustomData_has_layer(&mesh->vdata, CD_ORIGINDEX);
+    use_orig_index_edges = CustomData_has_layer(&mesh->edata, CD_ORIGINDEX);
+    use_orig_index_polys = CustomData_has_layer(&mesh->pdata, CD_ORIGINDEX);
   }
 
   geometry_set = compute_geometry(
       tree, *lf_graph_info, *output_node, std::move(geometry_set), nmd, ctx);
 
-  if (geometry_set.has_mesh()) {
-    /* Add #CD_ORIGINDEX layers if they don't exist already. This is required because the
-     * #eModifierTypeFlag_SupportsMapping flag is set. If the layers did not exist before, it is
-     * assumed that the output mesh does not have a mapping to the original mesh. */
-    Mesh &mesh = *geometry_set.get_mesh_for_write();
-    if (use_orig_index_verts) {
-      CustomData_add_layer(&mesh.vdata, CD_ORIGINDEX, CD_SET_DEFAULT, nullptr, mesh.totvert);
-    }
-    if (use_orig_index_edges) {
-      CustomData_add_layer(&mesh.edata, CD_ORIGINDEX, CD_SET_DEFAULT, nullptr, mesh.totedge);
-    }
-    if (use_orig_index_polys) {
-      CustomData_add_layer(&mesh.pdata, CD_ORIGINDEX, CD_SET_DEFAULT, nullptr, mesh.totpoly);
+  if (use_orig_index_verts || use_orig_index_edges || use_orig_index_polys) {
+    if (Mesh *mesh = geometry_set.get_mesh_for_write()) {
+      /* Add #CD_ORIGINDEX layers if they don't exist already. This is required because the
+       * #eModifierTypeFlag_SupportsMapping flag is set. If the layers did not exist before, it is
+       * assumed that the output mesh does not have a mapping to the original mesh. */
+      if (use_orig_index_verts) {
+        CustomData_add_layer(&mesh->vdata, CD_ORIGINDEX, CD_SET_DEFAULT, nullptr, mesh->totvert);
+      }
+      if (use_orig_index_edges) {
+        CustomData_add_layer(&mesh->edata, CD_ORIGINDEX, CD_SET_DEFAULT, nullptr, mesh->totedge);
+      }
+      if (use_orig_index_polys) {
+        CustomData_add_layer(&mesh->pdata, CD_ORIGINDEX, CD_SET_DEFAULT, nullptr, mesh->totpoly);
+      }
     }
   }
 }