Method BuildIndexBuffer

Source/Engine/Graphics/Models/ModelData.Tool.cpp:284–371

}

void MeshData::BuildIndexBuffer()
{
    PROFILE_CPU();
    Stopwatch stopwatch;

    const int32 vertexCount = Positions.Count();
    MeshData newMesh;
    newMesh.Indices.EnsureCapacity(vertexCount);
    Array<int32> mapping;
    mapping.Resize(vertexCount);
    int32 newVertexCounter = 0;

#if USE_SPATIAL_SORT
    // Set up a SpatialSort to quickly find all vertices close to a given position
    Assimp::SpatialSort vertexFinder;
    vertexFinder.Fill((const aiVector3D*)Positions.Get(), vertexCount, sizeof(Float3));
    std::vector<unsigned int> spatialSortCache;
#endif

    // Build index buffer
    for (int32 vertexIndex = 0; vertexIndex < vertexCount; vertexIndex++)
    {
        // Find duplicated vertex before the current one
        const int32 reuseVertexIndex = FindVertex(*this, vertexIndex, 0, vertexIndex, mapping
#if USE_SPATIAL_SORT
                                                  , vertexFinder, spatialSortCache
#endif
        );
        if (reuseVertexIndex == INVALID_INDEX)
        {
            newMesh.Indices.Add(newVertexCounter);
            mapping[vertexIndex] = newVertexCounter;
            newVertexCounter++;
        }
        else
        {
            // Remove vertex
            const int32 mapped = mapping[reuseVertexIndex];
            ASSERT(mapped != INVALID_INDEX && mapped < vertexIndex);
            newMesh.Indices.Add(mapped);
            mapping[vertexIndex] = INVALID_INDEX;
        }
    }

    // Skip if no change
    if (vertexCount == newVertexCounter)
        return;

    // Remove unused vertices
    newMesh.SwapBuffers(*this);
#define REMAP_BUFFER(name) RemapBuffer(newMesh.name, name, mapping, newVertexCounter)
    REMAP_BUFFER(Positions);
    REMAP_BUFFER(Normals);
    REMAP_BUFFER(Tangents);
    REMAP_BUFFER(BitangentSigns);
    REMAP_BUFFER(Colors);
    REMAP_BUFFER(BlendIndices);
    REMAP_BUFFER(BlendWeights);