Update meshoptimizer to v0.20

Source/ThirdParty/meshoptimizer/indexgenerator.cpp

@@ -4,6 +4,8 @@
 #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
 {
 
@@ -83,10 +85,49 @@ struct VertexStreamHasher
 	}
 };
 
+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)
+	while (buckets < count + count / 4)
 		buckets *= 2;
 
 	return buckets;
@@ -116,7 +157,43 @@ static T* hashLookup(T* table, size_t buckets, const Hash& hash, const T& key, c
 	}
 
 	assert(false && "Hash table is full"); // unreachable
-	return 0;
+	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 <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);
+		}
 }
 
 } // namespace meshopt
@@ -126,7 +203,7 @@ size_t meshopt_generateVertexRemap(unsigned int* destination, const unsigned int
 	using namespace meshopt;
 
 	assert(indices || index_count == vertex_count);
-	assert(index_count % 3 == 0);
+	assert(!indices || index_count % 3 == 0);
 	assert(vertex_size > 0 && vertex_size <= 256);
 
 	meshopt_Allocator allocator;
@@ -227,6 +304,8 @@ size_t meshopt_generateVertexRemapMulti(unsigned int* destination, const unsigne
 
 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;
@@ -239,14 +318,23 @@ void meshopt_remapVertexBuffer(void* destination, const void* vertices, size_t v
 		vertices = vertices_copy;
 	}
 
-	for (size_t i = 0; i < vertex_count; ++i)
+	// specialize the loop for common vertex sizes to ensure memcpy is compiled as an inlined intrinsic
+	switch (vertex_size)
 	{
-		if (remap[i] != ~0u)
-		{
-			assert(remap[i] < vertex_count);
+	case 4:
+		return remapVertices<4>(destination, vertices, vertex_count, vertex_size, remap);
 
-			memcpy(static_cast<unsigned char*>(destination) + remap[i] * vertex_size, static_cast<const unsigned char*>(vertices) + i * vertex_size, vertex_size);
-		}
+	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);
 	}
 }
 
@@ -345,3 +433,146 @@ void meshopt_generateShadowIndexBufferMulti(unsigned int* destination, const uns
 		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 >= 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));
+	}
+}