251 lines
9.1 KiB
C++
251 lines
9.1 KiB
C++
/* SPDX-FileCopyrightText: 2023 Blender Authors
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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/** \file
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* \ingroup bke
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*/
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#include "DNA_mesh_types.h"
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#include "DNA_meshdata_types.h"
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#include "DNA_object_types.h"
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#include "BLI_map.hh"
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#include "BLI_ordered_edge.hh"
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#include "BLI_task.hh"
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#include "BLI_threads.h"
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#include "BLI_timeit.hh"
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#include "BKE_attribute.hh"
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#include "BKE_customdata.hh"
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#include "BKE_mesh.hh"
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namespace blender::bke::calc_edges {
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/**
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* Return a hash value that is likely to be different in the low bits from the normal `hash()`
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* function. This is necessary to avoid collisions in #BKE_mesh_calc_edges.
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*/
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static uint64_t edge_hash_2(const OrderedEdge &edge)
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{
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return edge.v_low;
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}
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/* The map first contains an edge pointer and later an index. */
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union OrigEdgeOrIndex {
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const int2 *original_edge;
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int index;
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};
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using EdgeMap = Map<OrderedEdge, OrigEdgeOrIndex>;
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static void reserve_hash_maps(const Mesh *mesh,
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const bool keep_existing_edges,
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MutableSpan<EdgeMap> edge_maps)
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{
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const int totedge_guess = std::max(keep_existing_edges ? mesh->totedge : 0, mesh->faces_num * 2);
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threading::parallel_for_each(
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edge_maps, [&](EdgeMap &edge_map) { edge_map.reserve(totedge_guess / edge_maps.size()); });
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}
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static void add_existing_edges_to_hash_maps(Mesh *mesh,
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MutableSpan<EdgeMap> edge_maps,
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uint32_t parallel_mask)
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{
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/* Assume existing edges are valid. */
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const Span<int2> edges = mesh->edges();
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threading::parallel_for_each(edge_maps, [&](EdgeMap &edge_map) {
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const int task_index = &edge_map - edge_maps.data();
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for (const int2 &edge : edges) {
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OrderedEdge ordered_edge{edge[0], edge[1]};
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/* Only add the edge when it belongs into this map. */
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if (task_index == (parallel_mask & edge_hash_2(ordered_edge))) {
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edge_map.add_new(ordered_edge, {&edge});
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}
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}
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});
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}
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static void add_face_edges_to_hash_maps(Mesh *mesh,
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MutableSpan<EdgeMap> edge_maps,
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uint32_t parallel_mask)
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{
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const OffsetIndices faces = mesh->faces();
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const Span<int> corner_verts = mesh->corner_verts();
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threading::parallel_for_each(edge_maps, [&](EdgeMap &edge_map) {
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const int task_index = &edge_map - edge_maps.data();
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for (const int i : faces.index_range()) {
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const Span<int> face_verts = corner_verts.slice(faces[i]);
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int vert_prev = face_verts.last();
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for (const int vert : face_verts) {
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/* Can only be the same when the mesh data is invalid. */
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if (vert_prev != vert) {
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OrderedEdge ordered_edge{vert_prev, vert};
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/* Only add the edge when it belongs into this map. */
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if (task_index == (parallel_mask & edge_hash_2(ordered_edge))) {
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edge_map.lookup_or_add(ordered_edge, {nullptr});
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}
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}
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vert_prev = vert;
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}
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}
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});
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}
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static void serialize_and_initialize_deduplicated_edges(MutableSpan<EdgeMap> edge_maps,
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MutableSpan<int2> new_edges)
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{
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/* All edges are distributed in the hash tables now. They have to be serialized into a single
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* array below. To be able to parallelize this, we have to compute edge index offsets for each
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* map. */
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Array<int> edge_index_offsets(edge_maps.size());
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edge_index_offsets[0] = 0;
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for (const int i : IndexRange(edge_maps.size() - 1)) {
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edge_index_offsets[i + 1] = edge_index_offsets[i] + edge_maps[i].size();
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}
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threading::parallel_for_each(edge_maps, [&](EdgeMap &edge_map) {
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const int task_index = &edge_map - edge_maps.data();
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int new_edge_index = edge_index_offsets[task_index];
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for (EdgeMap::MutableItem item : edge_map.items()) {
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int2 &new_edge = new_edges[new_edge_index];
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const int2 *orig_edge = item.value.original_edge;
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if (orig_edge != nullptr) {
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/* Copy values from original edge. */
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new_edge = *orig_edge;
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}
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else {
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/* Initialize new edge. */
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new_edge[0] = item.key.v_low;
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new_edge[1] = item.key.v_high;
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}
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item.value.index = new_edge_index;
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new_edge_index++;
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}
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});
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}
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static void update_edge_indices_in_face_loops(const OffsetIndices<int> faces,
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const Span<int> corner_verts,
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const Span<EdgeMap> edge_maps,
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const uint32_t parallel_mask,
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MutableSpan<int> corner_edges)
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{
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threading::parallel_for(faces.index_range(), 100, [&](IndexRange range) {
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for (const int face_index : range) {
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const IndexRange face = faces[face_index];
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int prev_corner = face.last();
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for (const int next_corner : face) {
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const int vert = corner_verts[next_corner];
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const int vert_prev = corner_verts[prev_corner];
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int edge_index;
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if (vert_prev != vert) {
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OrderedEdge ordered_edge{vert_prev, vert};
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/* Double lookup: First find the map that contains the edge, then lookup the edge. */
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const EdgeMap &edge_map = edge_maps[parallel_mask & edge_hash_2(ordered_edge)];
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edge_index = edge_map.lookup(ordered_edge).index;
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}
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else {
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/* This is an invalid edge; normally this does not happen in Blender,
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* but it can be part of an imported mesh with invalid geometry. See
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* #76514. */
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edge_index = 0;
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}
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corner_edges[prev_corner] = edge_index;
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prev_corner = next_corner;
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}
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}
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});
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}
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static int get_parallel_maps_count(const Mesh *mesh)
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{
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/* Don't use parallelization when the mesh is small. */
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if (mesh->faces_num < 1000) {
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return 1;
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}
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/* Use at most 8 separate hash tables. Using more threads has diminishing returns. These threads
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* can better do something more useful instead. */
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const int system_thread_count = BLI_system_thread_count();
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return power_of_2_min_i(std::min(8, system_thread_count));
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}
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static void clear_hash_tables(MutableSpan<EdgeMap> edge_maps)
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{
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threading::parallel_for_each(edge_maps, [](EdgeMap &edge_map) { edge_map.clear(); });
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}
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} // namespace blender::bke::calc_edges
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void BKE_mesh_calc_edges(Mesh *mesh, bool keep_existing_edges, const bool select_new_edges)
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{
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using namespace blender;
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using namespace blender::bke;
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using namespace blender::bke::calc_edges;
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/* Parallelization is achieved by having multiple hash tables for different subsets of edges.
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* Each edge is assigned to one of the hash maps based on the lower bits of a hash value. */
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const int parallel_maps = get_parallel_maps_count(mesh);
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BLI_assert(is_power_of_2_i(parallel_maps));
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const uint32_t parallel_mask = uint32_t(parallel_maps) - 1;
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Array<EdgeMap> edge_maps(parallel_maps);
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reserve_hash_maps(mesh, keep_existing_edges, edge_maps);
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/* Add all edges. */
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if (keep_existing_edges) {
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calc_edges::add_existing_edges_to_hash_maps(mesh, edge_maps, parallel_mask);
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}
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calc_edges::add_face_edges_to_hash_maps(mesh, edge_maps, parallel_mask);
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/* Compute total number of edges. */
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int new_totedge = 0;
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for (EdgeMap &edge_map : edge_maps) {
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new_totedge += edge_map.size();
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}
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/* Create new edges. */
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MutableAttributeAccessor attributes = mesh->attributes_for_write();
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attributes.add<int>(".corner_edge", ATTR_DOMAIN_CORNER, AttributeInitConstruct());
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MutableSpan<int2> new_edges{
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static_cast<int2 *>(MEM_calloc_arrayN(new_totedge, sizeof(int2), __func__)), new_totedge};
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calc_edges::serialize_and_initialize_deduplicated_edges(edge_maps, new_edges);
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calc_edges::update_edge_indices_in_face_loops(mesh->faces(),
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mesh->corner_verts(),
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edge_maps,
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parallel_mask,
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mesh->corner_edges_for_write());
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/* Free old CustomData and assign new one. */
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CustomData_free(&mesh->edge_data, mesh->totedge);
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CustomData_reset(&mesh->edge_data);
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mesh->totedge = new_totedge;
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attributes.add<int2>(".edge_verts", ATTR_DOMAIN_EDGE, AttributeInitMoveArray(new_edges.data()));
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if (select_new_edges) {
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MutableAttributeAccessor attributes = mesh->attributes_for_write();
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SpanAttributeWriter<bool> select_edge = attributes.lookup_or_add_for_write_span<bool>(
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".select_edge", ATTR_DOMAIN_EDGE);
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if (select_edge) {
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int new_edge_index = 0;
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for (const EdgeMap &edge_map : edge_maps) {
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for (EdgeMap::Item item : edge_map.items()) {
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if (item.value.original_edge == nullptr) {
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select_edge.span[new_edge_index] = true;
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}
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new_edge_index++;
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}
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}
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select_edge.finish();
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}
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}
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if (!keep_existing_edges) {
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/* All edges are rebuilt from the faces, so there are no loose edges. */
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mesh->tag_loose_edges_none();
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}
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/* Explicitly clear edge maps, because that way it can be parallelized. */
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clear_hash_tables(edge_maps);
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}
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