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Source/ThirdParty/meshoptimizer/vcacheanalyzer.cpp

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+// This file is part of meshoptimizer library; see meshoptimizer.h for version/license details
+#include "meshoptimizer.h"
+
+#include <assert.h>
+#include <string.h>
+
+meshopt_VertexCacheStatistics meshopt_analyzeVertexCache(const unsigned int* indices, size_t index_count, size_t vertex_count, unsigned int cache_size, unsigned int warp_size, unsigned int primgroup_size)
+{
+	assert(index_count % 3 == 0);
+	assert(cache_size >= 3);
+	assert(warp_size == 0 || warp_size >= 3);
+
+	meshopt_Allocator allocator;
+
+	meshopt_VertexCacheStatistics result = {};
+
+	unsigned int warp_offset = 0;
+	unsigned int primgroup_offset = 0;
+
+	unsigned int* cache_timestamps = allocator.allocate<unsigned int>(vertex_count);
+	memset(cache_timestamps, 0, vertex_count * sizeof(unsigned int));
+
+	unsigned int timestamp = cache_size + 1;
+
+	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);
+
+		bool ac = (timestamp - cache_timestamps[a]) > cache_size;
+		bool bc = (timestamp - cache_timestamps[b]) > cache_size;
+		bool cc = (timestamp - cache_timestamps[c]) > cache_size;
+
+		// flush cache if triangle doesn't fit into warp or into the primitive buffer
+		if ((primgroup_size && primgroup_offset == primgroup_size) || (warp_size && warp_offset + ac + bc + cc > warp_size))
+		{
+			result.warps_executed += warp_offset > 0;
+
+			warp_offset = 0;
+			primgroup_offset = 0;
+
+			// reset cache
+			timestamp += cache_size + 1;
+		}
+
+		// update cache and add vertices to warp
+		for (int j = 0; j < 3; ++j)
+		{
+			unsigned int index = indices[i + j];
+
+			if (timestamp - cache_timestamps[index] > cache_size)
+			{
+				cache_timestamps[index] = timestamp++;
+				result.vertices_transformed++;
+				warp_offset++;
+			}
+		}
+
+		primgroup_offset++;
+	}
+
+	size_t unique_vertex_count = 0;
+
+	for (size_t i = 0; i < vertex_count; ++i)
+		unique_vertex_count += cache_timestamps[i] > 0;
+
+	result.warps_executed += warp_offset > 0;
+
+	result.acmr = index_count == 0 ? 0 : float(result.vertices_transformed) / float(index_count / 3);
+	result.atvr = unique_vertex_count == 0 ? 0 : float(result.vertices_transformed) / float(unique_vertex_count);
+
+	return result;
+}