552 lines
15 KiB
C++
552 lines
15 KiB
C++
// This file is part of meshoptimizer library; see meshoptimizer.h for version/license details
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#include "meshoptimizer.h"
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#include <assert.h>
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#include <string.h>
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// This work is based on:
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// John McDonald, Mark Kilgard. Crack-Free Point-Normal Triangles using Adjacent Edge Normals. 2010
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namespace meshopt
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{
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static unsigned int hashUpdate4(unsigned int h, const unsigned char* key, size_t len)
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{
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// MurmurHash2
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const unsigned int m = 0x5bd1e995;
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const int r = 24;
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while (len >= 4)
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{
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unsigned int k = *reinterpret_cast<const unsigned int*>(key);
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k *= m;
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k ^= k >> r;
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k *= m;
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h *= m;
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h ^= k;
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key += 4;
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len -= 4;
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}
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return h;
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}
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struct VertexHasher
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{
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const unsigned char* vertices;
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size_t vertex_size;
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size_t vertex_stride;
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size_t hash(unsigned int index) const
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{
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return hashUpdate4(0, vertices + index * vertex_stride, vertex_size);
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}
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bool equal(unsigned int lhs, unsigned int rhs) const
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{
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return memcmp(vertices + lhs * vertex_stride, vertices + rhs * vertex_stride, vertex_size) == 0;
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}
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};
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struct VertexStreamHasher
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{
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const meshopt_Stream* streams;
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size_t stream_count;
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size_t hash(unsigned int index) const
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{
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unsigned int h = 0;
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for (size_t i = 0; i < stream_count; ++i)
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{
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const meshopt_Stream& s = streams[i];
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const unsigned char* data = static_cast<const unsigned char*>(s.data);
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h = hashUpdate4(h, data + index * s.stride, s.size);
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}
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return h;
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}
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bool equal(unsigned int lhs, unsigned int rhs) const
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{
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for (size_t i = 0; i < stream_count; ++i)
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{
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const meshopt_Stream& s = streams[i];
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const unsigned char* data = static_cast<const unsigned char*>(s.data);
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if (memcmp(data + lhs * s.stride, data + rhs * s.stride, s.size) != 0)
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return false;
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}
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return true;
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}
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};
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struct EdgeHasher
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{
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const unsigned int* remap;
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size_t hash(unsigned long long edge) const
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{
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unsigned int e0 = unsigned(edge >> 32);
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unsigned int e1 = unsigned(edge);
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unsigned int h1 = remap[e0];
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unsigned int h2 = remap[e1];
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const unsigned int m = 0x5bd1e995;
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// MurmurHash64B finalizer
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h1 ^= h2 >> 18;
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h1 *= m;
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h2 ^= h1 >> 22;
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h2 *= m;
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h1 ^= h2 >> 17;
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h1 *= m;
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h2 ^= h1 >> 19;
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h2 *= m;
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return h2;
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}
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bool equal(unsigned long long lhs, unsigned long long rhs) const
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{
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unsigned int l0 = unsigned(lhs >> 32);
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unsigned int l1 = unsigned(lhs);
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unsigned int r0 = unsigned(rhs >> 32);
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unsigned int r1 = unsigned(rhs);
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return remap[l0] == remap[r0] && remap[l1] == remap[r1];
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}
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};
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static size_t hashBuckets(size_t count)
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{
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size_t buckets = 1;
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while (buckets < count + count / 4)
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buckets *= 2;
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return buckets;
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}
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template <typename T, typename Hash>
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static T* hashLookup(T* table, size_t buckets, const Hash& hash, const T& key, const T& empty)
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{
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assert(buckets > 0);
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assert((buckets & (buckets - 1)) == 0);
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size_t hashmod = buckets - 1;
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size_t bucket = hash.hash(key) & hashmod;
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for (size_t probe = 0; probe <= hashmod; ++probe)
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{
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T& item = table[bucket];
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if (item == empty)
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return &item;
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if (hash.equal(item, key))
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return &item;
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// hash collision, quadratic probing
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bucket = (bucket + probe + 1) & hashmod;
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}
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assert(false && "Hash table is full"); // unreachable
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return 0;
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}
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static void buildPositionRemap(unsigned int* remap, const float* vertex_positions, size_t vertex_count, size_t vertex_positions_stride, meshopt_Allocator& allocator)
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{
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VertexHasher vertex_hasher = {reinterpret_cast<const unsigned char*>(vertex_positions), 3 * sizeof(float), vertex_positions_stride};
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size_t vertex_table_size = hashBuckets(vertex_count);
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unsigned int* vertex_table = allocator.allocate<unsigned int>(vertex_table_size);
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memset(vertex_table, -1, vertex_table_size * sizeof(unsigned int));
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for (size_t i = 0; i < vertex_count; ++i)
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{
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unsigned int index = unsigned(i);
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unsigned int* entry = hashLookup(vertex_table, vertex_table_size, vertex_hasher, index, ~0u);
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if (*entry == ~0u)
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*entry = index;
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remap[index] = *entry;
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}
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}
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} // namespace meshopt
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size_t meshopt_generateVertexRemap(unsigned int* destination, const unsigned int* indices, size_t index_count, const void* vertices, size_t vertex_count, size_t vertex_size)
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{
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using namespace meshopt;
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assert(indices || index_count == vertex_count);
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assert(index_count % 3 == 0);
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assert(vertex_size > 0 && vertex_size <= 256);
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meshopt_Allocator allocator;
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memset(destination, -1, vertex_count * sizeof(unsigned int));
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VertexHasher hasher = {static_cast<const unsigned char*>(vertices), vertex_size, vertex_size};
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size_t table_size = hashBuckets(vertex_count);
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unsigned int* table = allocator.allocate<unsigned int>(table_size);
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memset(table, -1, table_size * sizeof(unsigned int));
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unsigned int next_vertex = 0;
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for (size_t i = 0; i < index_count; ++i)
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{
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unsigned int index = indices ? indices[i] : unsigned(i);
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assert(index < vertex_count);
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if (destination[index] == ~0u)
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{
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unsigned int* entry = hashLookup(table, table_size, hasher, index, ~0u);
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if (*entry == ~0u)
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{
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*entry = index;
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destination[index] = next_vertex++;
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}
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else
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{
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assert(destination[*entry] != ~0u);
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destination[index] = destination[*entry];
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}
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}
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}
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assert(next_vertex <= vertex_count);
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return next_vertex;
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}
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size_t meshopt_generateVertexRemapMulti(unsigned int* destination, const unsigned int* indices, size_t index_count, size_t vertex_count, const struct meshopt_Stream* streams, size_t stream_count)
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{
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using namespace meshopt;
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assert(indices || index_count == vertex_count);
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assert(index_count % 3 == 0);
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assert(stream_count > 0 && stream_count <= 16);
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for (size_t i = 0; i < stream_count; ++i)
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{
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assert(streams[i].size > 0 && streams[i].size <= 256);
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assert(streams[i].size <= streams[i].stride);
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}
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meshopt_Allocator allocator;
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memset(destination, -1, vertex_count * sizeof(unsigned int));
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VertexStreamHasher hasher = {streams, stream_count};
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size_t table_size = hashBuckets(vertex_count);
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unsigned int* table = allocator.allocate<unsigned int>(table_size);
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memset(table, -1, table_size * sizeof(unsigned int));
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unsigned int next_vertex = 0;
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for (size_t i = 0; i < index_count; ++i)
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{
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unsigned int index = indices ? indices[i] : unsigned(i);
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assert(index < vertex_count);
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if (destination[index] == ~0u)
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{
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unsigned int* entry = hashLookup(table, table_size, hasher, index, ~0u);
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if (*entry == ~0u)
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{
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*entry = index;
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destination[index] = next_vertex++;
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}
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else
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{
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assert(destination[*entry] != ~0u);
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destination[index] = destination[*entry];
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}
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}
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}
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assert(next_vertex <= vertex_count);
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return next_vertex;
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}
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void meshopt_remapVertexBuffer(void* destination, const void* vertices, size_t vertex_count, size_t vertex_size, const unsigned int* remap)
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{
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assert(vertex_size > 0 && vertex_size <= 256);
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meshopt_Allocator allocator;
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// support in-place remap
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if (destination == vertices)
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{
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unsigned char* vertices_copy = allocator.allocate<unsigned char>(vertex_count * vertex_size);
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memcpy(vertices_copy, vertices, vertex_count * vertex_size);
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vertices = vertices_copy;
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}
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for (size_t i = 0; i < vertex_count; ++i)
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{
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if (remap[i] != ~0u)
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{
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assert(remap[i] < vertex_count);
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memcpy(static_cast<unsigned char*>(destination) + remap[i] * vertex_size, static_cast<const unsigned char*>(vertices) + i * vertex_size, vertex_size);
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}
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}
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}
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void meshopt_remapIndexBuffer(unsigned int* destination, const unsigned int* indices, size_t index_count, const unsigned int* remap)
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{
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assert(index_count % 3 == 0);
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for (size_t i = 0; i < index_count; ++i)
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{
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unsigned int index = indices ? indices[i] : unsigned(i);
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assert(remap[index] != ~0u);
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destination[i] = remap[index];
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}
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}
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void meshopt_generateShadowIndexBuffer(unsigned int* destination, const unsigned int* indices, size_t index_count, const void* vertices, size_t vertex_count, size_t vertex_size, size_t vertex_stride)
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{
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using namespace meshopt;
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assert(indices);
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assert(index_count % 3 == 0);
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assert(vertex_size > 0 && vertex_size <= 256);
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assert(vertex_size <= vertex_stride);
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meshopt_Allocator allocator;
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unsigned int* remap = allocator.allocate<unsigned int>(vertex_count);
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memset(remap, -1, vertex_count * sizeof(unsigned int));
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VertexHasher hasher = {static_cast<const unsigned char*>(vertices), vertex_size, vertex_stride};
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size_t table_size = hashBuckets(vertex_count);
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unsigned int* table = allocator.allocate<unsigned int>(table_size);
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memset(table, -1, table_size * sizeof(unsigned int));
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for (size_t i = 0; i < index_count; ++i)
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{
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unsigned int index = indices[i];
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assert(index < vertex_count);
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if (remap[index] == ~0u)
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{
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unsigned int* entry = hashLookup(table, table_size, hasher, index, ~0u);
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if (*entry == ~0u)
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*entry = index;
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remap[index] = *entry;
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}
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destination[i] = remap[index];
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}
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}
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void meshopt_generateShadowIndexBufferMulti(unsigned int* destination, const unsigned int* indices, size_t index_count, size_t vertex_count, const struct meshopt_Stream* streams, size_t stream_count)
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{
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using namespace meshopt;
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assert(indices);
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assert(index_count % 3 == 0);
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assert(stream_count > 0 && stream_count <= 16);
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for (size_t i = 0; i < stream_count; ++i)
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{
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assert(streams[i].size > 0 && streams[i].size <= 256);
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assert(streams[i].size <= streams[i].stride);
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}
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meshopt_Allocator allocator;
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unsigned int* remap = allocator.allocate<unsigned int>(vertex_count);
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memset(remap, -1, vertex_count * sizeof(unsigned int));
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VertexStreamHasher hasher = {streams, stream_count};
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size_t table_size = hashBuckets(vertex_count);
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unsigned int* table = allocator.allocate<unsigned int>(table_size);
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memset(table, -1, table_size * sizeof(unsigned int));
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for (size_t i = 0; i < index_count; ++i)
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{
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unsigned int index = indices[i];
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assert(index < vertex_count);
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if (remap[index] == ~0u)
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{
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unsigned int* entry = hashLookup(table, table_size, hasher, index, ~0u);
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if (*entry == ~0u)
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*entry = index;
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remap[index] = *entry;
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}
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destination[i] = remap[index];
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}
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}
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void meshopt_generateAdjacencyIndexBuffer(unsigned int* destination, const unsigned int* indices, size_t index_count, const float* vertex_positions, size_t vertex_count, size_t vertex_positions_stride)
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{
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using namespace meshopt;
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assert(index_count % 3 == 0);
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assert(vertex_positions_stride > 0 && vertex_positions_stride <= 256);
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assert(vertex_positions_stride % sizeof(float) == 0);
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meshopt_Allocator allocator;
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static const int next[4] = {1, 2, 0, 1};
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// build position remap: for each vertex, which other (canonical) vertex does it map to?
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unsigned int* remap = allocator.allocate<unsigned int>(vertex_count);
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buildPositionRemap(remap, vertex_positions, vertex_count, vertex_positions_stride, allocator);
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// build edge set; this stores all triangle edges but we can look these up by any other wedge
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EdgeHasher edge_hasher = {remap};
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size_t edge_table_size = hashBuckets(index_count);
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unsigned long long* edge_table = allocator.allocate<unsigned long long>(edge_table_size);
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unsigned int* edge_vertex_table = allocator.allocate<unsigned int>(edge_table_size);
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memset(edge_table, -1, edge_table_size * sizeof(unsigned long long));
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memset(edge_vertex_table, -1, edge_table_size * sizeof(unsigned int));
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for (size_t i = 0; i < index_count; i += 3)
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{
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for (int e = 0; e < 3; ++e)
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{
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unsigned int i0 = indices[i + e];
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unsigned int i1 = indices[i + next[e]];
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unsigned int i2 = indices[i + next[e + 1]];
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assert(i0 < vertex_count && i1 < vertex_count && i2 < vertex_count);
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unsigned long long edge = ((unsigned long long)i0 << 32) | i1;
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unsigned long long* entry = hashLookup(edge_table, edge_table_size, edge_hasher, edge, ~0ull);
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if (*entry == ~0ull)
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{
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*entry = edge;
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// store vertex opposite to the edge
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edge_vertex_table[entry - edge_table] = i2;
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}
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}
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}
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// build resulting index buffer: 6 indices for each input triangle
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for (size_t i = 0; i < index_count; i += 3)
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{
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unsigned int patch[6];
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for (int e = 0; e < 3; ++e)
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{
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unsigned int i0 = indices[i + e];
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unsigned int i1 = indices[i + next[e]];
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assert(i0 < vertex_count && i1 < vertex_count);
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// note: this refers to the opposite edge!
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unsigned long long edge = ((unsigned long long)i1 << 32) | i0;
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unsigned long long* oppe = hashLookup(edge_table, edge_table_size, edge_hasher, edge, ~0ull);
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patch[e * 2 + 0] = i0;
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patch[e * 2 + 1] = (*oppe == ~0ull) ? i0 : edge_vertex_table[oppe - edge_table];
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}
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memcpy(destination + i * 2, patch, sizeof(patch));
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}
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}
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void meshopt_generateTessellationIndexBuffer(unsigned int* destination, const unsigned int* indices, size_t index_count, const float* vertex_positions, size_t vertex_count, size_t vertex_positions_stride)
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{
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using namespace meshopt;
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assert(index_count % 3 == 0);
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assert(vertex_positions_stride > 0 && vertex_positions_stride <= 256);
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assert(vertex_positions_stride % sizeof(float) == 0);
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meshopt_Allocator allocator;
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static const int next[3] = {1, 2, 0};
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// build position remap: for each vertex, which other (canonical) vertex does it map to?
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unsigned int* remap = allocator.allocate<unsigned int>(vertex_count);
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buildPositionRemap(remap, vertex_positions, vertex_count, vertex_positions_stride, allocator);
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// build edge set; this stores all triangle edges but we can look these up by any other wedge
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EdgeHasher edge_hasher = {remap};
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size_t edge_table_size = hashBuckets(index_count);
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unsigned long long* edge_table = allocator.allocate<unsigned long long>(edge_table_size);
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memset(edge_table, -1, edge_table_size * sizeof(unsigned long long));
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for (size_t i = 0; i < index_count; i += 3)
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{
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for (int e = 0; e < 3; ++e)
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{
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unsigned int i0 = indices[i + e];
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unsigned int i1 = indices[i + next[e]];
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assert(i0 < vertex_count && i1 < vertex_count);
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unsigned long long edge = ((unsigned long long)i0 << 32) | i1;
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unsigned long long* entry = hashLookup(edge_table, edge_table_size, edge_hasher, edge, ~0ull);
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if (*entry == ~0ull)
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*entry = edge;
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}
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}
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// build resulting index buffer: 12 indices for each input triangle
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for (size_t i = 0; i < index_count; i += 3)
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{
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unsigned int patch[12];
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for (int e = 0; e < 3; ++e)
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{
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unsigned int i0 = indices[i + e];
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unsigned int i1 = indices[i + next[e]];
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assert(i0 < vertex_count && i1 < vertex_count);
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// note: this refers to the opposite edge!
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unsigned long long edge = ((unsigned long long)i1 << 32) | i0;
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|
unsigned long long oppe = *hashLookup(edge_table, edge_table_size, edge_hasher, edge, ~0ull);
|
|
|
|
// use the same edge if opposite edge doesn't exist (border)
|
|
oppe = (oppe == ~0ull) ? edge : oppe;
|
|
|
|
// triangle index (0, 1, 2)
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|
patch[e] = i0;
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|
|
|
// opposite edge (3, 4; 5, 6; 7, 8)
|
|
patch[3 + e * 2 + 0] = unsigned(oppe);
|
|
patch[3 + e * 2 + 1] = unsigned(oppe >> 32);
|
|
|
|
// dominant vertex (9, 10, 11)
|
|
patch[9 + e] = remap[i0];
|
|
}
|
|
|
|
memcpy(destination + i * 4, patch, sizeof(patch));
|
|
}
|
|
}
|