Method GetChunkGeometry

Source/Engine/Terrain/TerrainManager.cpp:83–229

}

bool TerrainManager::GetChunkGeometry(DrawCall& drawCall, int32 chunkSize, int32 lodIndex)
{
    const int32 chunkSizeLOD0 = chunkSize;

    // Try fast lookup
    GeometryData* data;
    const uint32 key = (uint32)chunkSizeLOD0 | ((uint32)lodIndex << 20);
    if (Lookup.TryGet(key, data))
    {
        data->GetChunkGeometry(drawCall);
        return false;
    }

    ASSERT(chunkSize >= 3 && chunkSize < MAX_uint16);
    ASSERT(lodIndex >= 0 && lodIndex <= TERRAIN_MAX_LODS);

    ScopeLock lock(GeometryLocker);

    // Check if someone just created buffer
    if (Lookup.TryGet(key, data))
    {
        data->GetChunkGeometry(drawCall);
        return false;
    }
    PROFILE_MEM(LevelTerrain);

    // Prepare
    const int32 vertexCount = (chunkSize + 1) >> lodIndex;
    chunkSize = vertexCount - 1;
    const bool indexUse16bits = chunkSize * chunkSize * vertexCount < MAX_uint16;
    const int32 indexSize = indexUse16bits ? sizeof(uint16) : sizeof(uint32);
    const int32 indexCount = chunkSize * chunkSize * 2 * 3;
    const int32 vertexCount2 = vertexCount * vertexCount;
    const int32 vbSize = sizeof(TerrainVertex) * vertexCount2;
    const int32 ibSize = indexSize * indexCount;
    TempData.Clear();
    TempData.EnsureCapacity(Math::Max(vbSize, ibSize));

    // Create vertex buffer
    auto vb = GPUDevice::Instance->CreateBuffer(TEXT("TerrainChunk.VB"));
    auto vertex = (TerrainVertex*)TempData.Get();
    const float vertexTexelSnapTexCoord = 1.0f / chunkSize;
    for (int32 z = 0; z < vertexCount; z++)
    {
        for (int32 x = 0; x < vertexCount; x++)
        {
            vertex->TexCoord.X = x * vertexTexelSnapTexCoord;
            vertex->TexCoord.Y = z * vertexTexelSnapTexCoord;

            // Smooth LODs morphing based on Barycentric coordinates to morph to the lower LOD near chunk edges
            Float4 coord(vertex->TexCoord.Y, vertex->TexCoord.X, 1.0f - vertex->TexCoord.X, 1.0f - vertex->TexCoord.Y);

            // Apply some contrast
            const float AdjustPower = 0.3f;
            coord.X = Math::Pow(coord.X, AdjustPower);
            coord.Y = Math::Pow(coord.Y, AdjustPower);
            coord.Z = Math::Pow(coord.Z, AdjustPower);
            coord.W = Math::Pow(coord.W, AdjustPower);