[Bf-blender-cvs] [e3947dfd103] soc-2021-adaptive-cloth: adaptive_cloth: AdaptiveMesh: splittable edges indices set changes

[ishbosamiya]

Commit: e3947dfd103404a37527139054973d58f3a53db6
Author: ishbosamiya
Date:   Thu Aug 5 15:05:06 2021 +0530
Branches: soc-2021-adaptive-cloth
https://developer.blender.org/rBe3947dfd103404a37527139054973d58f3a53db6

adaptive_cloth: AdaptiveMesh: splittable edges indices set changes

Earlier, an edge wouldn't be tested for if one of it's verts was
already selected (for another edge). This would seems almost correct
but leads to non symmetrical remeshing. So it makes sense to get all
the splittable edges, sort them based on their size and then split the
edge only if it still exists in the mesh.

So changes added:
Give the entire set of splittable edges instead of maximally
independent.
Sort the set based on the edge size.

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

M	source/blender/blenkernel/intern/cloth_remesh.cc

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

diff --git a/source/blender/blenkernel/intern/cloth_remesh.cc b/source/blender/blenkernel/intern/cloth_remesh.cc
index e79e5b058b9..348bd31b3b5 100644
--- a/source/blender/blenkernel/intern/cloth_remesh.cc
+++ b/source/blender/blenkernel/intern/cloth_remesh.cc
@@ -36,6 +36,7 @@
 #include "BKE_cloth.h"
 #include "BKE_cloth_remesh.hh"
 
+#include <algorithm>
 #include <cstddef>
 #include <functional>
 #include <limits>
@@ -377,6 +378,10 @@ class AdaptiveMesh : public Mesh<NodeData<END>, VertData, EdgeData, internal::Em
     auto splittable_edges_set = this->get_splittable_edge_indices_set();
     do {
       for (const auto &edge_index : splittable_edges_set) {
+        auto op_edge = this->get_edges().get(edge_index);
+        if (!op_edge) {
+          continue;
+        }
         auto &edge = this->get_checked_edge(edge_index);
         auto mesh_diff = this->split_edge_triangulate(edge.get_self_index(), true);
 
@@ -440,22 +445,45 @@ class AdaptiveMesh : public Mesh<NodeData<END>, VertData, EdgeData, internal::Em
    */
   blender::Vector<EdgeIndex> get_splittable_edge_indices_set()
   {
+    /* TODO(ish): Reference [1] says that the splittable edges should
+     * be a set so this is done by checking if the verts are already
+     * selected or not.
+     *
+     * This can lead to non symmetrical remeshing which wouldn't be
+     * valid. So don't consider this at least for now. Will check
+     * later again to see if it makes sense.
+     *
+     * An example of why selected verts may not work.
+     *             v1__v2
+     *              |  /
+     *              | /
+     *              |/
+     *             /|v3
+     *            / |
+     *           /__|
+     *          v5   v4
+     *
+     * Splitting (v1, v3) (v3, v4) can be done without it affecting
+     * each other but one of the edges wouldn't be selected because v3
+     * was already selected. This can lead to non symmetrical
+     * splitting of the edges.
+     */
     /* Deselect all verts */
-    for (auto &vert : this->get_verts_mut()) {
-      auto &vert_data = vert.get_checked_extra_data_mut();
-      auto &flag = vert_data.get_flag_mut();
-      flag &= ~VERT_SELECTED_FOR_SPLIT;
-    }
+    /* for (auto &vert : this->get_verts_mut()) { */
+    /*   auto &vert_data = vert.get_checked_extra_data_mut(); */
+    /*   auto &flag = vert_data.get_flag_mut(); */
+    /*   flag &= ~VERT_SELECTED_FOR_SPLIT; */
+    /* } */
 
     blender::Vector<EdgeIndex> splittable_edge_indices;
     /* It is assumed that the edges sizes have been computed earlier
      * and stored in the extra data of the edges */
     for (const auto &edge : this->get_edges()) {
       auto [v1, v2] = this->get_checked_verts_of_edge(edge, false);
-      if (v1.get_checked_extra_data().get_flag() & VERT_SELECTED_FOR_SPLIT ||
-          v2.get_checked_extra_data().get_flag() & VERT_SELECTED_FOR_SPLIT) {
-        continue;
-      }
+      /* if (v1.get_checked_extra_data().get_flag() & VERT_SELECTED_FOR_SPLIT || */
+      /*     v2.get_checked_extra_data().get_flag() & VERT_SELECTED_FOR_SPLIT) { */
+      /*   continue; */
+      /* } */
       const auto &edge_data = edge.get_checked_extra_data();
       auto edge_size = edge_data.get_size();
       if (edge_size > 1.0) {
@@ -469,6 +497,18 @@ class AdaptiveMesh : public Mesh<NodeData<END>, VertData, EdgeData, internal::Em
       }
     }
 
+    /* Sort all the splittable edges based on their edge size,
+     * largest to smallest. */
+    std::sort(splittable_edge_indices.begin(),
+              splittable_edge_indices.end(),
+              [this](const auto &edge_index_1, const auto &edge_index_2) {
+                const auto &edge_1 = this->get_checked_edge(edge_index_1);
+                const auto &edge_2 = this->get_checked_edge(edge_index_2);
+
+                return edge_1.get_checked_extra_data().get_size() >
+                       edge_2.get_checked_extra_data().get_size();
+              });
+
     return splittable_edge_indices;
   }