godot/thirdparty/meshoptimizer/vfetchanalyzer.cpp
reduz 77a045e902 Rework Mesh handling on scene importing.
-Reworked how meshes are treated by importer by using EditorSceneImporterMesh and EditorSceneImporterMeshNode. Instead of Mesh and MeshInstance, this allows more efficient processing of meshes before they are actually registered in the RenderingServer.
-Integrated MeshOptimizer
-Reworked internals of SurfaceTool to use arrays, making it more performant and easy to run optimizatons on.
2020-12-13 21:29:51 -03:00

59 lines
1.7 KiB
C++

// This file is part of meshoptimizer library; see meshoptimizer.h for version/license details
#include "meshoptimizer.h"
#include <assert.h>
#include <string.h>
meshopt_VertexFetchStatistics meshopt_analyzeVertexFetch(const unsigned int* indices, size_t index_count, size_t vertex_count, size_t vertex_size)
{
assert(index_count % 3 == 0);
assert(vertex_size > 0 && vertex_size <= 256);
meshopt_Allocator allocator;
meshopt_VertexFetchStatistics result = {};
unsigned char* vertex_visited = allocator.allocate<unsigned char>(vertex_count);
memset(vertex_visited, 0, vertex_count);
const size_t kCacheLine = 64;
const size_t kCacheSize = 128 * 1024;
// simple direct mapped cache; on typical mesh data this is close to 4-way cache, and this model is a gross approximation anyway
size_t cache[kCacheSize / kCacheLine] = {};
for (size_t i = 0; i < index_count; ++i)
{
unsigned int index = indices[i];
assert(index < vertex_count);
vertex_visited[index] = 1;
size_t start_address = index * vertex_size;
size_t end_address = start_address + vertex_size;
size_t start_tag = start_address / kCacheLine;
size_t end_tag = (end_address + kCacheLine - 1) / kCacheLine;
assert(start_tag < end_tag);
for (size_t tag = start_tag; tag < end_tag; ++tag)
{
size_t line = tag % (sizeof(cache) / sizeof(cache[0]));
// we store +1 since cache is filled with 0 by default
result.bytes_fetched += (cache[line] != tag + 1) * kCacheLine;
cache[line] = tag + 1;
}
}
size_t unique_vertex_count = 0;
for (size_t i = 0; i < vertex_count; ++i)
unique_vertex_count += vertex_visited[i];
result.overfetch = unique_vertex_count == 0 ? 0 : float(result.bytes_fetched) / float(unique_vertex_count * vertex_size);
return result;
}