348 lines
8.2 KiB
C++
348 lines
8.2 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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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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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)
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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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} // 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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