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