[Bf-blender-cvs] [4cfa4f7551e] master: Geometry Nodes: Parallelize flip faces node

[Hans Goudey]

Commit: 4cfa4f7551ee537bdefd99c0b3d93243fdcb729b
Author: Hans Goudey
Date:   Thu Jan 19 14:14:12 2023 -0600
Branches: master
https://developer.blender.org/rB4cfa4f7551ee537bdefd99c0b3d93243fdcb729b

Geometry Nodes: Parallelize flip faces node

I observed a 2x performance improvement for a large mesh.

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

M	source/blender/nodes/geometry/nodes/node_geo_flip_faces.cc

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

diff --git a/source/blender/nodes/geometry/nodes/node_geo_flip_faces.cc b/source/blender/nodes/geometry/nodes/node_geo_flip_faces.cc
index e88ade18764..561579aef88 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_flip_faces.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_flip_faces.cc
@@ -1,11 +1,10 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 
+#include "BLI_task.hh"
+
 #include "BKE_mesh.h"
 #include "BKE_mesh_runtime.h"
 
-#include "DNA_mesh_types.h"
-#include "DNA_meshdata_types.h"
-
 #include "BKE_attribute_math.hh"
 
 #include "node_geometry_util.hh"
@@ -33,16 +32,18 @@ static void mesh_flip_faces(Mesh &mesh, const Field<bool> &selection_field)
   const Span<MPoly> polys = mesh.polys();
   MutableSpan<MLoop> loops = mesh.loops_for_write();
 
-  for (const int i : selection.index_range()) {
-    const MPoly &poly = polys[selection[i]];
-    int start = poly.loopstart;
-    for (const int j : IndexRange(poly.totloop / 2)) {
-      const int index1 = start + j + 1;
-      const int index2 = start + poly.totloop - j - 1;
-      std::swap(loops[index1].v, loops[index2].v);
-      std::swap(loops[index1 - 1].e, loops[index2].e);
+  threading::parallel_for(selection.index_range(), 1024, [&](const IndexRange range) {
+    for (const int i : selection.slice(range)) {
+      const IndexRange poly(polys[i].loopstart, polys[i].totloop);
+      int start = poly.start();
+      for (const int j : IndexRange(poly.size() / 2)) {
+        const int index1 = start + j + 1;
+        const int index2 = start + poly.size() - j - 1;
+        std::swap(loops[index1].v, loops[index2].v);
+        std::swap(loops[index1 - 1].e, loops[index2].e);
+      }
     }
-  }
+  });
 
   MutableAttributeAccessor attributes = mesh.attributes_for_write();
   attributes.for_all(
@@ -56,10 +57,12 @@ static void mesh_flip_faces(Mesh &mesh, const Field<bool> &selection_field)
           attribute_math::convert_to_static_type(meta_data.data_type, [&](auto dummy) {
             using T = decltype(dummy);
             MutableSpan<T> dst_span = attribute.span.typed<T>();
-            for (const int j : selection.index_range()) {
-              const MPoly &poly = polys[selection[j]];
-              dst_span.slice(poly.loopstart + 1, poly.totloop - 1).reverse();
-            }
+            threading::parallel_for(selection.index_range(), 1024, [&](const IndexRange range) {
+              for (const int i : selection.slice(range)) {
+                const IndexRange poly(polys[i].loopstart, polys[i].totloop);
+                dst_span.slice(poly.drop_front(1)).reverse();
+              }
+            });
           });
           attribute.finish();
         }