Initial release

third_party/meshoptimizer/allocator.cpp

@@ -0,0 +1,21 @@
+// This file is part of meshoptimizer library; see meshoptimizer.h for version/license details
+#include "meshoptimizer.h"
+
+#include <assert.h>
+
+#ifdef MESHOPTIMIZER_ALLOC_EXPORT
+meshopt_Allocator::Storage& meshopt_Allocator::storage()
+{
+	static Storage s = {::operator new, ::operator delete };
+	return s;
+}
+#endif
+
+void meshopt_setAllocator(void* (MESHOPTIMIZER_ALLOC_CALLCONV* allocate)(size_t), void (MESHOPTIMIZER_ALLOC_CALLCONV* deallocate)(void*))
+{
+	assert(allocate && deallocate);
+
+	meshopt_Allocator::Storage& s = meshopt_Allocator::storage();
+	s.allocate = allocate;
+	s.deallocate = deallocate;
+}

third_party/meshoptimizer/indexgenerator.cpp

@@ -0,0 +1,817 @@
+// 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:
+// Matthias Teschner, Bruno Heidelberger, Matthias Mueller, Danat Pomeranets, Markus Gross. Optimized Spatial Hashing for Collision Detection of Deformable Objects. 2003
+// John McDonald, Mark Kilgard. Crack-Free Point-Normal Triangles using Adjacent Edge Normals. 2010
+// John Hable. Variable Rate Shading with Visibility Buffer Rendering. 2024
+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 VertexCustomHasher
+{
+	const float* vertex_positions;
+	size_t vertex_stride_float;
+
+	int (*callback)(void*, unsigned int, unsigned int);
+	void* context;
+
+	size_t hash(unsigned int index) const
+	{
+		const unsigned int* key = reinterpret_cast<const unsigned int*>(vertex_positions + index * vertex_stride_float);
+
+		unsigned int x = key[0], y = key[1], z = key[2];
+
+		// replace negative zero with zero
+		x = (x == 0x80000000) ? 0 : x;
+		y = (y == 0x80000000) ? 0 : y;
+		z = (z == 0x80000000) ? 0 : z;
+
+		// scramble bits to make sure that integer coordinates have entropy in lower bits
+		x ^= x >> 17;
+		y ^= y >> 17;
+		z ^= z >> 17;
+
+		// Optimized Spatial Hashing for Collision Detection of Deformable Objects
+		return (x * 73856093) ^ (y * 19349663) ^ (z * 83492791);
+	}
+
+	bool equal(unsigned int lhs, unsigned int rhs) const
+	{
+		const float* lp = vertex_positions + lhs * vertex_stride_float;
+		const float* rp = vertex_positions + rhs * vertex_stride_float;
+
+		if (lp[0] != rp[0] || lp[1] != rp[1] || lp[2] != rp[2])
+			return false;
+
+		return callback ? callback(context, lhs, rhs) : true;
+	}
+};
+
+struct TriangleKey
+{
+	unsigned int a, b, c;
+
+	bool operator==(const TriangleKey& other) const
+	{
+		return a == other.a && b == other.b && c == other.c;
+	}
+};
+
+struct TriangleKeyHasher
+{
+	size_t hash(const TriangleKey& k) const
+	{
+		// Optimized Spatial Hashing for Collision Detection of Deformable Objects
+		return (k.a * 73856093) ^ (k.b * 19349663) ^ (k.c * 83492791);
+	}
+
+	bool equal(const TriangleKey& lhs, const TriangleKey& rhs) const
+	{
+		return lhs == rhs;
+	}
+};
+
+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 NULL;
+}
+
+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;
+	}
+
+	allocator.deallocate(vertex_table);
+}
+
+template <typename Hash>
+static size_t generateVertexRemap(unsigned int* remap, const unsigned int* indices, size_t index_count, size_t vertex_count, const Hash& hash, meshopt_Allocator& allocator)
+{
+	memset(remap, -1, vertex_count * sizeof(unsigned int));
+
+	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 (remap[index] != ~0u)
+			continue;
+
+		unsigned int* entry = hashLookup(table, table_size, hash, index, ~0u);
+
+		if (*entry == ~0u)
+		{
+			*entry = index;
+			remap[index] = next_vertex++;
+		}
+		else
+		{
+			assert(remap[*entry] != ~0u);
+			remap[index] = remap[*entry];
+		}
+	}
+
+	assert(next_vertex <= vertex_count);
+	return next_vertex;
+}
+
+template <size_t BlockSize>
+static void remapVertices(void* destination, const void* vertices, size_t vertex_count, size_t vertex_size, const unsigned int* remap)
+{
+	size_t block_size = BlockSize == 0 ? vertex_size : BlockSize;
+	assert(block_size == vertex_size);
+
+	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] * block_size, static_cast<const unsigned char*>(vertices) + i * block_size, block_size);
+		}
+}
+
+template <typename Hash>
+static void generateShadowBuffer(unsigned int* destination, const unsigned int* indices, size_t index_count, size_t vertex_count, const Hash& hash, meshopt_Allocator& allocator)
+{
+	unsigned int* remap = allocator.allocate<unsigned int>(vertex_count);
+	memset(remap, -1, vertex_count * sizeof(unsigned int));
+
+	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, hash, index, ~0u);
+
+			if (*entry == ~0u)
+				*entry = index;
+
+			remap[index] = *entry;
+		}
+
+		destination[i] = remap[index];
+	}
+}
+
+static size_t filterIndexBuffer(unsigned int* destination, const unsigned int* indices, size_t index_count, const unsigned int* remap, size_t vertex_count, meshopt_Allocator& allocator)
+{
+	(void)vertex_count;
+
+	TriangleKeyHasher hasher = {};
+	TriangleKey empty = {~0u, ~0u, ~0u};
+
+	size_t face_count = index_count / 3;
+	size_t table_size = hashBuckets(face_count);
+	TriangleKey* table = allocator.allocate<TriangleKey>(table_size);
+	memset(table, -1, table_size * sizeof(TriangleKey));
+
+	size_t write = 0;
+
+	for (size_t i = 0; i < face_count; ++i)
+	{
+		unsigned int a = indices[i * 3 + 0], b = indices[i * 3 + 1], c = indices[i * 3 + 2];
+		assert(a < vertex_count && b < vertex_count && c < vertex_count);
+
+		unsigned int ra = remap[a], rb = remap[b], rc = remap[c];
+
+		// degenerate triangle
+		if (ra == rb || ra == rc || rb == rc)
+			continue;
+
+		// canonicalize triangle wrt winding preserving rotation
+		if (rb < ra && rb < rc)
+		{
+			// abc -> bca
+			unsigned int t = ra;
+			ra = rb, rb = rc, rc = t;
+		}
+		else if (rc < ra && rc < rb)
+		{
+			// abc -> cab
+			unsigned int t = rc;
+			rc = rb, rb = ra, ra = t;
+		}
+
+		TriangleKey key = {ra, rb, rc};
+		TriangleKey* entry = hashLookup(table, table_size, hasher, key, empty);
+
+		// duplicate triangle
+		if (entry->a != ~0u)
+			continue;
+
+		*entry = key;
+
+		destination[write + 0] = a;
+		destination[write + 1] = b;
+		destination[write + 2] = c;
+		write += 3;
+	}
+
+	return write;
+}
+
+} // 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(vertex_size > 0 && vertex_size <= 256);
+
+	meshopt_Allocator allocator;
+	VertexHasher hasher = {static_cast<const unsigned char*>(vertices), vertex_size, vertex_size};
+
+	return generateVertexRemap(destination, indices, index_count, vertex_count, hasher, allocator);
+}
+
+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(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;
+	VertexStreamHasher hasher = {streams, stream_count};
+
+	return generateVertexRemap(destination, indices, index_count, vertex_count, hasher, allocator);
+}
+
+size_t meshopt_generateVertexRemapCustom(unsigned int* destination, const unsigned int* indices, size_t index_count, const float* vertex_positions, size_t vertex_count, size_t vertex_positions_stride, int (*callback)(void*, unsigned int, unsigned int), void* context)
+{
+	using namespace meshopt;
+
+	assert(indices || index_count == vertex_count);
+	assert(vertex_positions_stride >= 12 && vertex_positions_stride <= 256);
+	assert(vertex_positions_stride % sizeof(float) == 0);
+
+	meshopt_Allocator allocator;
+	VertexCustomHasher hasher = {vertex_positions, vertex_positions_stride / sizeof(float), callback, context};
+
+	return generateVertexRemap(destination, indices, index_count, vertex_count, hasher, allocator);
+}
+
+void meshopt_remapVertexBuffer(void* destination, const void* vertices, size_t vertex_count, size_t vertex_size, const unsigned int* remap)
+{
+	using namespace meshopt;
+
+	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;
+	}
+
+	// specialize the loop for common vertex sizes to ensure memcpy is compiled as an inlined intrinsic
+	switch (vertex_size)
+	{
+	case 4:
+		return remapVertices<4>(destination, vertices, vertex_count, vertex_size, remap);
+
+	case 8:
+		return remapVertices<8>(destination, vertices, vertex_count, vertex_size, remap);
+
+	case 12:
+		return remapVertices<12>(destination, vertices, vertex_count, vertex_size, remap);
+
+	case 16:
+		return remapVertices<16>(destination, vertices, vertex_count, vertex_size, remap);
+
+	default:
+		return remapVertices<0>(destination, vertices, vertex_count, vertex_size, remap);
+	}
+}
+
+void meshopt_remapIndexBuffer(unsigned int* destination, const unsigned int* indices, size_t index_count, const unsigned int* remap)
+{
+	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];
+	}
+}
+
+size_t meshopt_filterIndexBuffer(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(index_count % 3 == 0);
+	assert(vertex_size > 0 && vertex_size <= 256);
+	assert(vertex_size <= vertex_stride);
+
+	meshopt_Allocator allocator;
+	VertexHasher hasher = {static_cast<const unsigned char*>(vertices), vertex_size, vertex_stride};
+
+	unsigned int* remap = allocator.allocate<unsigned int>(vertex_count);
+	generateVertexRemap(remap, indices, index_count, vertex_count, hasher, allocator);
+
+	return filterIndexBuffer(destination, indices, index_count, remap, vertex_count, allocator);
+}
+
+size_t meshopt_filterIndexBufferMulti(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(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;
+	VertexStreamHasher hasher = {streams, stream_count};
+
+	unsigned int* remap = allocator.allocate<unsigned int>(vertex_count);
+	generateVertexRemap(remap, indices, index_count, vertex_count, hasher, allocator);
+
+	return filterIndexBuffer(destination, indices, index_count, remap, vertex_count, allocator);
+}
+
+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(index_count % 3 == 0);
+	assert(vertex_size > 0 && vertex_size <= 256);
+	assert(vertex_size <= vertex_stride);
+
+	meshopt_Allocator allocator;
+	VertexHasher hasher = {static_cast<const unsigned char*>(vertices), vertex_size, vertex_stride};
+
+	generateShadowBuffer(destination, indices, index_count, vertex_count, hasher, allocator);
+}
+
+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(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;
+	VertexStreamHasher hasher = {streams, stream_count};
+
+	generateShadowBuffer(destination, indices, index_count, vertex_count, hasher, allocator);
+}
+
+void meshopt_generatePositionRemap(unsigned int* destination, const float* vertex_positions, size_t vertex_count, size_t vertex_positions_stride)
+{
+	using namespace meshopt;
+
+	assert(vertex_positions_stride >= 12 && vertex_positions_stride <= 256);
+	assert(vertex_positions_stride % sizeof(float) == 0);
+
+	meshopt_Allocator allocator;
+	VertexCustomHasher hasher = {vertex_positions, vertex_positions_stride / sizeof(float), NULL, NULL};
+
+	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 < vertex_count; ++i)
+	{
+		unsigned int* entry = hashLookup(table, table_size, hasher, unsigned(i), ~0u);
+
+		if (*entry == ~0u)
+			*entry = unsigned(i);
+
+		destination[i] = *entry;
+	}
+}
+
+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 >= 12 && 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 >= 12 && 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));
+	}
+}
+
+size_t meshopt_generateProvokingIndexBuffer(unsigned int* destination, unsigned int* reorder, const unsigned int* indices, size_t index_count, size_t vertex_count)
+{
+	assert(index_count % 3 == 0);
+
+	meshopt_Allocator allocator;
+
+	unsigned int* remap = allocator.allocate<unsigned int>(vertex_count);
+	memset(remap, -1, vertex_count * sizeof(unsigned int));
+
+	// compute vertex valence; this is used to prioritize least used corner
+	// note: we use 8-bit counters for performance; for outlier vertices the valence is incorrect but that just affects the heuristic
+	unsigned char* valence = allocator.allocate<unsigned char>(vertex_count);
+	memset(valence, 0, vertex_count);
+
+	for (size_t i = 0; i < index_count; ++i)
+	{
+		unsigned int index = indices[i];
+		assert(index < vertex_count);
+
+		valence[index]++;
+	}
+
+	unsigned int reorder_offset = 0;
+
+	// assign provoking vertices; leave the rest for the next pass
+	for (size_t i = 0; i < index_count; i += 3)
+	{
+		unsigned int a = indices[i + 0], b = indices[i + 1], c = indices[i + 2];
+		assert(a < vertex_count && b < vertex_count && c < vertex_count);
+
+		// try to rotate triangle such that provoking vertex hasn't been seen before
+		// if multiple vertices are new, prioritize the one with least valence
+		// this reduces the risk that a future triangle will have all three vertices seen
+		unsigned int va = remap[a] == ~0u ? valence[a] : ~0u;
+		unsigned int vb = remap[b] == ~0u ? valence[b] : ~0u;
+		unsigned int vc = remap[c] == ~0u ? valence[c] : ~0u;
+
+		if (vb != ~0u && vb <= va && vb <= vc)
+		{
+			// abc -> bca
+			unsigned int t = a;
+			a = b, b = c, c = t;
+		}
+		else if (vc != ~0u && vc <= va && vc <= vb)
+		{
+			// abc -> cab
+			unsigned int t = c;
+			c = b, b = a, a = t;
+		}
+
+		unsigned int newidx = reorder_offset;
+
+		// now remap[a] = ~0u or all three vertices are old
+		// recording remap[a] makes it possible to remap future references to the same index, conserving space
+		if (remap[a] == ~0u)
+			remap[a] = newidx;
+
+		// we need to clone the provoking vertex to get a unique index
+		// if all three are used the choice is arbitrary since no future triangle will be able to reuse any of these
+		reorder[reorder_offset++] = a;
+
+		// note: first vertex is final, the other two will be fixed up in next pass
+		destination[i + 0] = newidx;
+		destination[i + 1] = b;
+		destination[i + 2] = c;
+
+		// update vertex valences for corner heuristic
+		valence[a]--;
+		valence[b]--;
+		valence[c]--;
+	}
+
+	// remap or clone non-provoking vertices (iterating to skip provoking vertices)
+	int step = 1;
+
+	for (size_t i = 1; i < index_count; i += step, step ^= 3)
+	{
+		unsigned int index = destination[i];
+
+		if (remap[index] == ~0u)
+		{
+			// we haven't seen the vertex before as a provoking vertex
+			// to maintain the reference to the original vertex we need to clone it
+			unsigned int newidx = reorder_offset;
+
+			remap[index] = newidx;
+			reorder[reorder_offset++] = index;
+		}
+
+		destination[i] = remap[index];
+	}
+
+	assert(reorder_offset <= vertex_count + index_count / 3);
+	return reorder_offset;
+}

third_party/meshoptimizer/vfetchoptimizer.cpp

@@ -0,0 +1,71 @@
+// This file is part of meshoptimizer library; see meshoptimizer.h for version/license details
+#include "meshoptimizer.h"
+
+#include <assert.h>
+#include <string.h>
+
+size_t meshopt_optimizeVertexFetchRemap(unsigned int* destination, const unsigned int* indices, size_t index_count, size_t vertex_count)
+{
+	memset(destination, -1, vertex_count * sizeof(unsigned int));
+
+	unsigned int next_vertex = 0;
+
+	for (size_t i = 0; i < index_count; ++i)
+	{
+		unsigned int index = indices[i];
+		assert(index < vertex_count);
+
+		if (destination[index] == ~0u)
+		{
+			destination[index] = next_vertex++;
+		}
+	}
+
+	assert(next_vertex <= vertex_count);
+
+	return next_vertex;
+}
+
+size_t meshopt_optimizeVertexFetch(void* destination, unsigned int* indices, size_t index_count, const void* vertices, size_t vertex_count, size_t vertex_size)
+{
+	assert(vertex_size > 0 && vertex_size <= 256);
+
+	meshopt_Allocator allocator;
+
+	// support in-place optimization
+	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;
+	}
+
+	// build vertex remap table
+	unsigned int* vertex_remap = allocator.allocate<unsigned int>(vertex_count);
+	memset(vertex_remap, -1, vertex_count * sizeof(unsigned int));
+
+	unsigned int next_vertex = 0;
+
+	for (size_t i = 0; i < index_count; ++i)
+	{
+		unsigned int index = indices[i];
+		assert(index < vertex_count);
+
+		unsigned int& remap = vertex_remap[index];
+
+		if (remap == ~0u) // vertex was not added to destination VB
+		{
+			// add vertex
+			memcpy(static_cast<unsigned char*>(destination) + next_vertex * vertex_size, static_cast<const unsigned char*>(vertices) + index * vertex_size, vertex_size);
+
+			remap = next_vertex++;
+		}
+
+		// modify indices in place
+		indices[i] = remap;
+	}
+
+	assert(next_vertex <= vertex_count);
+
+	return next_vertex;
+}

third_party/xatlas/xatlas.h

@@ -0,0 +1,269 @@
+/*
+MIT License
+
+Copyright (c) 2018-2020 Jonathan Young
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+/*
+thekla_atlas
+MIT License
+https://github.com/Thekla/thekla_atlas
+Copyright (c) 2013 Thekla, Inc
+Copyright NVIDIA Corporation 2006 -- Ignacio Castano <icastano@nvidia.com>
+*/
+#pragma once
+#ifndef XATLAS_H
+#define XATLAS_H
+#include <stddef.h>
+#include <stdint.h>
+
+namespace xatlas {
+
+enum class ChartType
+{
+	Planar,
+	Ortho,
+	LSCM,
+	Piecewise,
+	Invalid
+};
+
+// A group of connected faces, belonging to a single atlas.
+struct Chart
+{
+	uint32_t *faceArray;
+	uint32_t atlasIndex; // Sub-atlas index.
+	uint32_t faceCount;
+	ChartType type;
+	uint32_t material;
+};
+
+// Output vertex.
+struct Vertex
+{
+	int32_t atlasIndex; // Sub-atlas index. -1 if the vertex doesn't exist in any atlas.
+	int32_t chartIndex; // -1 if the vertex doesn't exist in any chart.
+	float uv[2]; // Not normalized - values are in Atlas width and height range.
+	uint32_t xref; // Index of input vertex from which this output vertex originated.
+};
+
+// Output mesh.
+struct Mesh
+{
+	Chart *chartArray;
+	uint32_t *indexArray;
+	Vertex *vertexArray;
+	uint32_t chartCount;
+	uint32_t indexCount;
+	uint32_t vertexCount;
+};
+
+static const uint32_t kImageChartIndexMask = 0x1FFFFFFF;
+static const uint32_t kImageHasChartIndexBit = 0x80000000;
+static const uint32_t kImageIsBilinearBit = 0x40000000;
+static const uint32_t kImageIsPaddingBit = 0x20000000;
+
+// Empty on creation. Populated after charts are packed.
+struct Atlas
+{
+	uint32_t *image;
+	Mesh *meshes; // The output meshes, corresponding to each AddMesh call.
+	float *utilization; // Normalized atlas texel utilization array. E.g. a value of 0.8 means 20% empty space. atlasCount in length.
+	uint32_t width; // Atlas width in texels.
+	uint32_t height; // Atlas height in texels.
+	uint32_t atlasCount; // Number of sub-atlases. Equal to 0 unless PackOptions resolution is changed from default (0).
+	uint32_t chartCount; // Total number of charts in all meshes.
+	uint32_t meshCount; // Number of output meshes. Equal to the number of times AddMesh was called.
+	float texelsPerUnit; // Equal to PackOptions texelsPerUnit if texelsPerUnit > 0, otherwise an estimated value to match PackOptions resolution.
+};
+
+// Create an empty atlas.
+Atlas *Create();
+
+void Destroy(Atlas *atlas);
+
+enum class IndexFormat
+{
+	UInt16,
+	UInt32
+};
+
+// Input mesh declaration.
+struct MeshDecl
+{
+	const void *vertexPositionData = nullptr;
+	const void *vertexNormalData = nullptr; // optional
+	const void *vertexUvData = nullptr; // optional. The input UVs are provided as a hint to the chart generator.
+	const void *indexData = nullptr; // optional
+
+	// Optional. Must be faceCount in length.
+	// Don't atlas faces set to true. Ignored faces still exist in the output meshes, Vertex uv is set to (0, 0) and Vertex atlasIndex to -1.
+	const bool *faceIgnoreData = nullptr;
+
+	// Optional. Must be faceCount in length.
+	// Only faces with the same material will be assigned to the same chart.
+	const uint32_t *faceMaterialData = nullptr;
+
+	// Optional. Must be faceCount in length.
+	// Polygon / n-gon support. Faces are assumed to be triangles if this is null.
+	const uint8_t *faceVertexCount = nullptr;
+
+	uint32_t vertexCount = 0;
+	uint32_t vertexPositionStride = 0;
+	uint32_t vertexNormalStride = 0; // optional
+	uint32_t vertexUvStride = 0; // optional
+	uint32_t indexCount = 0;
+	int32_t indexOffset = 0; // optional. Add this offset to all indices.
+	uint32_t faceCount = 0; // Optional if faceVertexCount is null. Otherwise assumed to be indexCount / 3.
+	IndexFormat indexFormat = IndexFormat::UInt16;
+
+	// Vertex positions within epsilon distance of each other are considered colocal.
+	float epsilon = 1.192092896e-07F;
+};
+
+enum class AddMeshError
+{
+	Success, // No error.
+	Error, // Unspecified error.
+	IndexOutOfRange, // An index is >= MeshDecl vertexCount.
+	InvalidFaceVertexCount, // Must be >= 3.
+	InvalidIndexCount // Not evenly divisible by 3 - expecting triangles.
+};
+
+// Add a mesh to the atlas. MeshDecl data is copied, so it can be freed after AddMesh returns.
+AddMeshError AddMesh(Atlas *atlas, const MeshDecl &meshDecl, uint32_t meshCountHint = 0);
+
+// Wait for AddMesh async processing to finish. ComputeCharts / Generate call this internally.
+void AddMeshJoin(Atlas *atlas);
+
+struct UvMeshDecl
+{
+	const void *vertexUvData = nullptr;
+	const void *indexData = nullptr; // optional
+	const uint32_t *faceMaterialData = nullptr; // Optional. Overlapping UVs should be assigned a different material. Must be indexCount / 3 in length.
+	uint32_t vertexCount = 0;
+	uint32_t vertexStride = 0;
+	uint32_t indexCount = 0;
+	int32_t indexOffset = 0; // optional. Add this offset to all indices.
+	IndexFormat indexFormat = IndexFormat::UInt16;
+};
+
+AddMeshError AddUvMesh(Atlas *atlas, const UvMeshDecl &decl);
+
+// Custom parameterization function. texcoords initial values are an orthogonal parameterization.
+typedef void (*ParameterizeFunc)(const float *positions, float *texcoords, uint32_t vertexCount, const uint32_t *indices, uint32_t indexCount);
+
+struct ChartOptions
+{
+	ParameterizeFunc paramFunc = nullptr;
+
+	float maxChartArea = 0.0f; // Don't grow charts to be larger than this. 0 means no limit.
+	float maxBoundaryLength = 0.0f; // Don't grow charts to have a longer boundary than this. 0 means no limit.
+
+	// Weights determine chart growth. Higher weights mean higher cost for that metric.
+	float normalDeviationWeight = 2.0f; // Angle between face and average chart normal.
+	float roundnessWeight = 0.01f;
+	float straightnessWeight = 6.0f;
+	float normalSeamWeight = 4.0f; // If > 1000, normal seams are fully respected.
+	float textureSeamWeight = 0.5f;
+
+	float maxCost = 2.0f; // If total of all metrics * weights > maxCost, don't grow chart. Lower values result in more charts.
+	uint32_t maxIterations = 1; // Number of iterations of the chart growing and seeding phases. Higher values result in better charts.
+
+	bool useInputMeshUvs = false; // Use MeshDecl::vertexUvData for charts.
+	bool fixWinding = false; // Enforce consistent texture coordinate winding.
+};
+
+// Call after all AddMesh calls. Can be called multiple times to recompute charts with different options.
+void ComputeCharts(Atlas *atlas, ChartOptions options = ChartOptions());
+
+struct PackOptions
+{
+	// Charts larger than this will be scaled down. 0 means no limit.
+	uint32_t maxChartSize = 0;
+
+	// Number of pixels to pad charts with.
+	uint32_t padding = 0;
+
+	// Unit to texel scale. e.g. a 1x1 quad with texelsPerUnit of 32 will take up approximately 32x32 texels in the atlas.
+	// If 0, an estimated value will be calculated to approximately match the given resolution.
+	// If resolution is also 0, the estimated value will approximately match a 1024x1024 atlas.
+	float texelsPerUnit = 0.0f;
+
+	// If 0, generate a single atlas with texelsPerUnit determining the final resolution.
+	// If not 0, and texelsPerUnit is not 0, generate one or more atlases with that exact resolution.
+	// If not 0, and texelsPerUnit is 0, texelsPerUnit is estimated to approximately match the resolution.
+	uint32_t resolution = 0;
+
+	// Leave space around charts for texels that would be sampled by bilinear filtering.
+	bool bilinear = true;
+
+	// Align charts to 4x4 blocks. Also improves packing speed, since there are fewer possible chart locations to consider.
+	bool blockAlign = false;
+
+	// Slower, but gives the best result. If false, use random chart placement.
+	bool bruteForce = false;
+
+	// Create Atlas::image
+	bool createImage = false;
+
+	// Rotate charts to the axis of their convex hull.
+	bool rotateChartsToAxis = true;
+
+	// Rotate charts to improve packing.
+	bool rotateCharts = true;
+};
+
+// Call after ComputeCharts. Can be called multiple times to re-pack charts with different options.
+void PackCharts(Atlas *atlas, PackOptions packOptions = PackOptions());
+
+// Equivalent to calling ComputeCharts and PackCharts in sequence. Can be called multiple times to regenerate with different options.
+void Generate(Atlas *atlas, ChartOptions chartOptions = ChartOptions(), PackOptions packOptions = PackOptions());
+
+// Progress tracking.
+enum class ProgressCategory
+{
+	AddMesh,
+	ComputeCharts,
+	PackCharts,
+	BuildOutputMeshes
+};
+
+// May be called from any thread. Return false to cancel.
+typedef bool (*ProgressFunc)(ProgressCategory category, int progress, void *userData);
+
+void SetProgressCallback(Atlas *atlas, ProgressFunc progressFunc = nullptr, void *progressUserData = nullptr);
+
+// Custom memory allocation.
+typedef void *(*ReallocFunc)(void *, size_t);
+typedef void (*FreeFunc)(void *);
+void SetAlloc(ReallocFunc reallocFunc, FreeFunc freeFunc = nullptr);
+
+// Custom print function.
+typedef int (*PrintFunc)(const char *, ...);
+void SetPrint(PrintFunc print, bool verbose);
+
+// Helper functions for error messages.
+const char *StringForEnum(AddMeshError error);
+const char *StringForEnum(ProgressCategory category);
+
+} // namespace xatlas
+
+#endif // XATLAS_H