[Bf-blender-cvs] [c5ed6fab1fa] soc-2021-adaptive-cloth: adaptive_cloth: fix: Mesh: collapse_edge_triangulate() invalid faces generated

[ishbosamiya]

Commit: c5ed6fab1fa46610e7d2947539ab99b0fafa192e
Author: ishbosamiya
Date:   Tue Jul 13 10:36:06 2021 +0530
Branches: soc-2021-adaptive-cloth
https://developer.blender.org/rBc5ed6fab1fa46610e7d2947539ab99b0fafa192e

adaptive_cloth: fix: Mesh: collapse_edge_triangulate() invalid faces generated

The edge between v1 and ov should be removed only if the edge doesn't have any linked faces. If it has any linked faces, it will make those faces invalid and cause problems down the line. For the face to have (v2, ov, vx), this becomes impossible since (v1, ov) has been removed, this is wrong.

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

M	source/blender/blenkernel/BKE_cloth_remesh.hh

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

diff --git a/source/blender/blenkernel/BKE_cloth_remesh.hh b/source/blender/blenkernel/BKE_cloth_remesh.hh
index fbed31942a1..d77e91a73e6 100644
--- a/source/blender/blenkernel/BKE_cloth_remesh.hh
+++ b/source/blender/blenkernel/BKE_cloth_remesh.hh
@@ -1201,14 +1201,10 @@ template<typename END, typename EVD, typename EED, typename EFD> class Mesh {
     /* TODO(ish): ensure normal information properly, right now need
      * to just assume it is not dirty for faster development */
     this->node_normals_dirty = false;
-
-    std::cout << __func__ << " mesh:" << std::endl << *this << std::endl;
   }
 
   MeshIO write() const
   {
-    std::cout << __func__ << " mesh:" << std::endl << *this << std::endl;
-
     using FaceData = std::tuple<usize, usize, usize>;
     blender::Vector<float3> positions;
     blender::Vector<float2> uvs;
@@ -1317,8 +1313,6 @@ template<typename END, typename EVD, typename EED, typename EFD> class Mesh {
       }
     }
 
-    /* std::cout << "line_indices: " << line_indices << std::endl; */
-
     MeshIO result;
     result.set_positions(std::move(positions));
     result.set_uvs(std::move(uvs));
@@ -1326,8 +1320,6 @@ template<typename END, typename EVD, typename EED, typename EFD> class Mesh {
     result.set_face_indices(std::move(face_indices));
     result.set_line_indices(std::move(line_indices));
 
-    std::cout << "MeshIO result: " << std::endl << result << std::endl;
-
     return result;
   }
 
@@ -1383,8 +1375,6 @@ template<typename END, typename EVD, typename EED, typename EFD> class Mesh {
       edge_indices = this->get_connecting_edge_indices(edge_node_1, edge_node_2);
     }
 
-    std::cout << "edge_indices: " << edge_indices << std::endl;
-
     /* Create the new new by interpolating the nodes of the edge */
     auto &new_node = this->add_empty_interp_node(edge_node_1, edge_node_2);
 
@@ -1549,10 +1539,6 @@ template<typename END, typename EVD, typename EED, typename EFD> class Mesh {
     auto [v1_a, v2] = this->get_checked_verts_of_edge(e, verts_swapped);
     auto v1_index = v1_a.self_index;
     auto v2_index = v2.self_index;
-    {
-      std::cout << "v1_index: " << v1_index << std::endl;
-      std::cout << "v2_index: " << v2_index << std::endl;
-    }
     BLI_assert(v1_a.node); /* ensure v1 has a node */
     auto n1_index = v1_a.node.value();
 
@@ -1563,21 +1549,21 @@ template<typename END, typename EVD, typename EED, typename EFD> class Mesh {
       this->delink_face_edges(face_index);
       auto face = this->delete_face(face_index);
 
-      std::cout << "face_edges: " << this->get_edge_indices_of_face(face) << std::endl;
-
       auto &ov = this->get_checked_other_vert(e, face);
 
       auto op_v1_ov_edge_index = this->get_connecting_edge_index(v1_index, ov.self_index);
       BLI_assert(op_v1_ov_edge_index);
-      auto v1_ov_edge = this->delete_edge(op_v1_ov_edge_index.value());
-
+      auto v1_ov_edge = this->get_checked_edge(op_v1_ov_edge_index.value());
+      /* delete `v1_ov_edge` only if it doesn't have any faces */
+      if (v1_ov_edge.faces.is_empty()) {
+        auto v1_ov_edge = this->delete_edge(op_v1_ov_edge_index.value());
+        deleted_edges.append(std::move(v1_ov_edge));
+      }
       deleted_faces.append(std::move(face));
-      deleted_edges.append(std::move(v1_ov_edge));
     }
 
     auto &v1 = this->get_checked_vert(v1_index);
     auto v1_edge_indices = v1.edges;
-    std::cout << "v1_edge_indices: " << v1_edge_indices << std::endl;
 
     /* edges should have verts (v2, vx) instead of (v1, vx) and the
      * face should have (v2, vx, vy) instead of (v1, vx, vy) */
@@ -1587,8 +1573,6 @@ template<typename END, typename EVD, typename EED, typename EFD> class Mesh {
       BLI_assert(v1_vx_edge.verts);
       auto &verts = v1_vx_edge.verts.value();
 
-      std::cout << "v1_vx_edge.verts: " << verts << std::endl;
-
       if (v1_vx_edge.has_vert(v2_index)) {
         /* don't need to mess with (v1, v2), only (v1, vx) */
         continue;
@@ -1601,8 +1585,6 @@ template<typename END, typename EVD, typename EED, typename EFD> class Mesh {
         v1_vx_edge.verts = {std::get<0>(verts), v2_index};
       }
 
-      /* TODO(ish): this particular `v1_vx_edge_index` should be
-       * removed from v1, cannot just clear out `v1.edges` */
       /* since the edge no longer refers to `v1`, we should remove the
        * edge from `v1.edges` */
       v1.edges.remove_first_occurrence_and_reorder(v1_vx_edge_index);