Function FixMips

Source/Engine/Terrain/TerrainPatch.cpp:566–628

}

void FixMips(const TerrainDataUpdateInfo& info, TextureBase::InitData* initData, int32 pixelStride)
{
    PROFILE_CPU_NAMED("Terrain.FixMips");

    for (int32 mipIndex = 1; mipIndex < initData->Mips.Count(); mipIndex++)
    {
        auto& mip = initData->Mips[mipIndex];
        auto& mipHigher = initData->Mips[mipIndex - 1];
        byte* mipData = mip.Data.Get();
        const byte* mipDataHigher = mipHigher.Data.Get();
        const int32 vertexCountEdgeMip = info.VertexCountEdge >> mipIndex;
        const int32 textureSizeMip = info.TextureSize >> mipIndex;
        const int32 vertexCountEdgeMipHigher = vertexCountEdgeMip << 1;
        const int32 textureSizeMipHigher = textureSizeMip << 1;

        // Make heightmap values on left edge the same as the left edge of the chunk on the higher LOD
        for (int32 chunkX = 0; chunkX < Terrain::ChunksCountEdge; chunkX++)
        {
            for (int32 chunkZ = 0; chunkZ < Terrain::ChunksCountEdge; chunkZ++)
            {
                const int32 chunkTextureX = chunkX * vertexCountEdgeMip;
                const int32 chunkTextureZ = chunkZ * vertexCountEdgeMip;

                const int32 chunkTextureXHigher = chunkX * vertexCountEdgeMipHigher;
                const int32 chunkTextureZHigher = chunkZ * vertexCountEdgeMipHigher;

                // Exclude patch edges
                int32 z = 0, zCount = vertexCountEdgeMip;
                int32 x = 0, xCount = vertexCountEdgeMip;
                if (chunkX == 0)
                    x = 1;
                else if (chunkX == Terrain::ChunksCountEdge - 1)
                    xCount--;
                if (chunkZ == 0)
                    z = 1;
                else if (chunkZ == Terrain::ChunksCountEdge - 1)
                    zCount--;

                for (; z < zCount; z++)
                {
                    const int32 textureIndex = (chunkTextureZ + z) * textureSizeMip + chunkTextureX;

                    const int32 zHigher = (int32)(((float)z / vertexCountEdgeMip) * vertexCountEdgeMipHigher);
                    const int32 textureIndexHigherMip = (chunkTextureZHigher + zHigher) * textureSizeMipHigher + chunkTextureXHigher;
                    const byte* higherMipData = mipDataHigher + textureIndexHigherMip * pixelStride;

                    Platform::MemoryCopy(mipData + textureIndex * pixelStride, higherMipData, pixelStride);
                }

                for (; x < xCount; x++)
                {
                    const int32 textureIndex = chunkTextureZ * textureSizeMip + chunkTextureX + x;

                    const int32 xHigher = (int32)(((float)x / vertexCountEdgeMip) * vertexCountEdgeMipHigher);
                    const int32 textureIndexHigherMip = chunkTextureZHigher * textureSizeMipHigher + chunkTextureXHigher + xHigher;
                    const byte* higherMipData = mipDataHigher + textureIndexHigherMip * pixelStride;

                    Platform::MemoryCopy(mipData + textureIndex * pixelStride, higherMipData, pixelStride);