269 lines
9.3 KiB
C++
269 lines
9.3 KiB
C++
/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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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_edgehash.h"
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#include "BLI_map.hh"
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#include "BLI_math_base.h"
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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_customdata.h"
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#include "BKE_mesh.h"
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namespace blender::bke::calc_edges {
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/** This is used to uniquely identify edges in a hash map. */
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struct OrderedEdge {
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int v_low, v_high;
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OrderedEdge(const int v1, const int v2)
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{
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if (v1 < v2) {
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v_low = v1;
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v_high = v2;
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}
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else {
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v_low = v2;
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v_high = v1;
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}
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}
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OrderedEdge(const uint v1, const uint v2)
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: OrderedEdge(static_cast<int>(v1), static_cast<int>(v2))
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{
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}
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uint64_t hash() const
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{
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return (this->v_low << 8) ^ this->v_high;
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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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uint64_t hash2() const
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{
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return this->v_low;
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}
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friend bool operator==(const OrderedEdge &e1, const OrderedEdge &e2)
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{
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BLI_assert(e1.v_low < e1.v_high);
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BLI_assert(e2.v_low < e2.v_high);
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return e1.v_low == e2.v_low && e1.v_high == e2.v_high;
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}
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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 MEdge *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->totpoly * 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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threading::parallel_for_each(edge_maps, [&](EdgeMap &edge_map) {
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const int task_index = &edge_map - &edge_maps[0];
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for (const MEdge &edge : Span(mesh->medge, mesh->totedge)) {
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OrderedEdge ordered_edge{edge.v1, edge.v2};
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/* Only add the edge when it belongs into this map. */
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if (task_index == (parallel_mask & ordered_edge.hash2())) {
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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_polygon_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 Span<MLoop> loops{mesh->mloop, mesh->totloop};
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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[0];
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for (const MPoly &poly : Span(mesh->mpoly, mesh->totpoly)) {
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Span<MLoop> poly_loops = loops.slice(poly.loopstart, poly.totloop);
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const MLoop *prev_loop = &poly_loops.last();
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for (const MLoop &next_loop : poly_loops) {
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/* Can only be the same when the mesh data is invalid. */
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if (prev_loop->v != next_loop.v) {
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OrderedEdge ordered_edge{prev_loop->v, next_loop.v};
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/* Only add the edge when it belongs into this map. */
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if (task_index == (parallel_mask & ordered_edge.hash2())) {
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edge_map.lookup_or_add(ordered_edge, {nullptr});
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}
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}
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prev_loop = &next_loop;
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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<MEdge> new_edges,
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short new_edge_flag)
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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[0];
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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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MEdge &new_edge = new_edges[new_edge_index];
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const MEdge *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.v1 = item.key.v_low;
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new_edge.v2 = item.key.v_high;
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new_edge.flag = new_edge_flag;
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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_poly_loops(Mesh *mesh,
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Span<EdgeMap> edge_maps,
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uint32_t parallel_mask)
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{
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const MutableSpan<MLoop> loops{mesh->mloop, mesh->totloop};
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threading::parallel_for(IndexRange(mesh->totpoly), 100, [&](IndexRange range) {
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for (const int poly_index : range) {
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MPoly &poly = mesh->mpoly[poly_index];
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MutableSpan<MLoop> poly_loops = loops.slice(poly.loopstart, poly.totloop);
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MLoop *prev_loop = &poly_loops.last();
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for (MLoop &next_loop : poly_loops) {
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int edge_index;
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if (prev_loop->v != next_loop.v) {
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OrderedEdge ordered_edge{prev_loop->v, next_loop.v};
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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 & ordered_edge.hash2()];
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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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* T76514. */
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edge_index = 0;
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}
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prev_loop->e = edge_index;
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prev_loop = &next_loop;
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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->totpoly < 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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/**
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* Calculate edges from polygons.
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*/
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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 = static_cast<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_polygon_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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MutableSpan<MEdge> new_edges{
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static_cast<MEdge *>(MEM_calloc_arrayN(new_totedge, sizeof(MEdge), __func__)), new_totedge};
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const short new_edge_flag = (ME_EDGEDRAW | ME_EDGERENDER) | (select_new_edges ? SELECT : 0);
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calc_edges::serialize_and_initialize_deduplicated_edges(edge_maps, new_edges, new_edge_flag);
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calc_edges::update_edge_indices_in_poly_loops(mesh, edge_maps, parallel_mask);
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/* Free old CustomData and assign new one. */
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CustomData_free(&mesh->edata, mesh->totedge);
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CustomData_reset(&mesh->edata);
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CustomData_add_layer(&mesh->edata, CD_MEDGE, CD_ASSIGN, new_edges.data(), new_totedge);
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mesh->totedge = new_totedge;
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mesh->medge = new_edges.data();
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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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