4 files changed, 63 insertions, 15 deletions

diff --git a/source/blender/blenkernel/BKE_mesh_mapping.h b/source/blender/blenkernel/BKE_mesh_mapping.h
index 2ee50fbaaee..350c4c4bb36 100644
--- a/source/blender/blenkernel/BKE_mesh_mapping.h
+++ b/source/blender/blenkernel/BKE_mesh_mapping.h
@@ -7,6 +7,10 @@
  */
 
 #ifdef __cplusplus
+#  include "BLI_array.hh"
+#endif
+
+#ifdef __cplusplus
 extern "C" {
 #endif
 
@@ -330,3 +334,19 @@ int *BKE_mesh_calc_smoothgroups(const struct MEdge *medge,
 #ifdef __cplusplus
 }
 #endif
+
+#ifdef __cplusplus
+namespace blender::mesh_topology {
+
+Array<int> build_corner_to_poly_map(Span<MPoly> polys, int loops_num);
+
+Array<Vector<int>> build_vert_to_edge_map(Span<MEdge> edges, int verts_num);
+Array<Vector<int>> build_vert_to_corner_map(Span<MLoop> loops, int verts_num);
+
+inline int previous_poly_corner(const MPoly &poly, int corner_i)
+{
+  return corner_i - 1 + (corner_i == poly.loopstart) * poly.totloop;
+}
+
+}  // namespace blender::mesh_topology
+#endif
diff --git a/source/blender/blenkernel/intern/mesh_fair.cc b/source/blender/blenkernel/intern/mesh_fair.cc
index bb0a5610cf4..df61169fa5c 100644
--- a/source/blender/blenkernel/intern/mesh_fair.cc
+++ b/source/blender/blenkernel/intern/mesh_fair.cc
@@ -26,6 +26,7 @@
 #include "MEM_guardedalloc.h"
 #include "eigen_capi.h"
 
+using blender::Array;
 using blender::Map;
 using blender::MutableSpan;
 using blender::Span;
@@ -220,12 +221,7 @@ class MeshFairingContext : public FairingContext {
       }
     }
 
-    loop_to_poly_map_.reserve(mesh->totloop);
-    for (int i = 0; i < mesh->totpoly; i++) {
-      for (int l = 0; l < mpoly_[i].totloop; l++) {
-        loop_to_poly_map_[l + mpoly_[i].loopstart] = i;
-      }
-    }
+    loop_to_poly_map_ = blender::mesh_topology::build_corner_to_poly_map(mpoly_, mloop_.size());
   }
 
   ~MeshFairingContext() override
@@ -259,7 +255,7 @@ class MeshFairingContext : public FairingContext {
   Span<MLoop> mloop_;
   Span<MPoly> mpoly_;
   Span<MEdge> medge_;
-  Vector<int> loop_to_poly_map_;
+  Array<int> loop_to_poly_map_;
 };
 
 class BMeshFairingContext : public FairingContext {
diff --git a/source/blender/blenkernel/intern/mesh_mapping.cc b/source/blender/blenkernel/intern/mesh_mapping.cc
index 2db0adce033..c1523f0a525 100644
--- a/source/blender/blenkernel/intern/mesh_mapping.cc
+++ b/source/blender/blenkernel/intern/mesh_mapping.cc
@@ -16,6 +16,7 @@
 #include "BLI_bitmap.h"
 #include "BLI_buffer.h"
 #include "BLI_math.h"
+#include "BLI_task.hh"
 #include "BLI_utildefines.h"
 
 #include "BKE_customdata.h"
@@ -552,6 +553,41 @@ void BKE_mesh_origindex_map_create_looptri(MeshElemMap **r_map,
   *r_mem = indices;
 }
 
+namespace blender::mesh_topology {
+
+Array<int> build_corner_to_poly_map(const Span<MPoly> polys, const int loops_num)
+{
+  Array<int> map(loops_num);
+  threading::parallel_for(polys.index_range(), 1024, [&](IndexRange range) {
+    for (const int64_t poly_i : range) {
+      const MPoly &poly = polys[poly_i];
+      map.as_mutable_span().slice(poly.loopstart, poly.totloop).fill(int(poly_i));
+    }
+  });
+  return map;
+}
+
+Array<Vector<int>> build_vert_to_edge_map(const Span<MEdge> edges, const int verts_num)
+{
+  Array<Vector<int>> map(verts_num);
+  for (const int64_t i : edges.index_range()) {
+    map[edges[i].v1].append(int(i));
+    map[edges[i].v2].append(int(i));
+  }
+  return map;
+}
+
+Array<Vector<int>> build_vert_to_corner_map(const Span<MLoop> loops, const int verts_num)
+{
+  Array<Vector<int>> map(verts_num);
+  for (const int64_t i : loops.index_range()) {
+    map[loops[i].v].append(int(i));
+  }
+  return map;
+}
+
+}  // namespace blender::mesh_topology
+
 /** \} */
 
 /* -------------------------------------------------------------------- */
diff --git a/source/blender/render/intern/texture_margin.cc b/source/blender/render/intern/texture_margin.cc
index 201908234fe..a69449d9386 100644
--- a/source/blender/render/intern/texture_margin.cc
+++ b/source/blender/render/intern/texture_margin.cc
@@ -14,6 +14,7 @@
 #include "BKE_DerivedMesh.h"
 #include "BKE_customdata.h"
 #include "BKE_mesh.h"
+#include "BKE_mesh_mapping.h"
 
 #include "DNA_mesh_types.h"
 #include "DNA_meshdata_types.h"
@@ -44,7 +45,7 @@ class TextureMarginMap {
   /** Maps UV-edges to their corresponding UV-edge. */
   Vector<int> loop_adjacency_map_;
   /** Maps UV-edges to their corresponding polygon. */
-  Vector<int> loop_to_poly_map_;
+  Array<int> loop_to_poly_map_;
 
   int w_, h_;
   float uv_offset_[2];
@@ -289,13 +290,8 @@ class TextureMarginMap {
 
   void build_tables()
   {
-    loop_to_poly_map_.resize(totloop_);
-    for (int i = 0; i < totpoly_; i++) {
-      for (int j = 0; j < mpoly_[i].totloop; j++) {
-        int l = j + mpoly_[i].loopstart;
-        loop_to_poly_map_[l] = i;
-      }
-    }
+    loop_to_poly_map_ = blender::mesh_topology::build_corner_to_poly_map({mpoly_, totpoly_},
+                                                                         totloop_);
 
     loop_adjacency_map_.resize(totloop_, -1);