Function CookCollision

Source/Engine/Terrain/TerrainPatch.cpp:668–736

}

bool CookCollision(TerrainDataUpdateInfo& info, TextureBase::InitData* initData, int32 collisionLod, Array<byte>* collisionData)
{
#if COMPILE_WITH_PHYSICS_COOKING
    info.GetSplatMaps();
    PROFILE_CPU_NAMED("Terrain.CookCollision");

    // Prepare data
    const int32 collisionLOD = Math::Clamp<int32>(collisionLod, 0, initData->Mips.Count() - 1);
    const int32 collisionLODInv = (int32)Math::Pow(2.0f, (float)collisionLOD);
    const int32 heightFieldChunkSize = ((info.ChunkSize + 1) >> collisionLOD) - 1;
    const int32 heightFieldSize = heightFieldChunkSize * Terrain::ChunksCountEdge + 1;
    const int32 heightFieldLength = heightFieldSize * heightFieldSize;
    GET_TERRAIN_SCRATCH_BUFFER(heightFieldData, heightFieldLength, PhysicsBackend::HeightFieldSample);
    PhysicsBackend::HeightFieldSample sample;
    Platform::MemoryClear(&sample, sizeof(PhysicsBackend::HeightFieldSample));
    Platform::MemoryClear(heightFieldData, sizeof(PhysicsBackend::HeightFieldSample) * heightFieldLength);

    // Setup terrain collision information
    const auto& mip = initData->Mips[collisionLOD];
    const int32 vertexCountEdgeMip = info.VertexCountEdge >> collisionLOD;
    const int32 textureSizeMip = info.TextureSize >> collisionLOD;
    for (int32 chunkX = 0; chunkX < Terrain::ChunksCountEdge; chunkX++)
    {
        const int32 chunkTextureX = chunkX * vertexCountEdgeMip;
        const int32 chunkStartX = chunkX * heightFieldChunkSize;
        for (int32 chunkZ = 0; chunkZ < Terrain::ChunksCountEdge; chunkZ++)
        {
            const int32 chunkTextureZ = chunkZ * vertexCountEdgeMip;
            const int32 chunkStartZ = chunkZ * heightFieldChunkSize;
            for (int32 z = 0; z < vertexCountEdgeMip; z++)
            {
                const int32 heightmapZ = chunkStartZ + z;
                for (int32 x = 0; x < vertexCountEdgeMip; x++)
                {
                    const int32 heightmapX = chunkStartX + x;

                    const int32 textureIndex = (chunkTextureZ + z) * textureSizeMip + chunkTextureX + x;
                    const Color32 raw = mip.Data.Get<Color32>()[textureIndex];
                    sample.Height = int16(TERRAIN_PATCH_COLLISION_QUANTIZATION * ReadNormalizedHeight(raw));
                    sample.MaterialIndex0 = sample.MaterialIndex1 = GetPhysicalMaterial(raw, info, chunkZ, chunkX, z * collisionLODInv, x * collisionLODInv);

                    const int32 dstIndex = (heightmapX * heightFieldSize) + heightmapZ;
                    heightFieldData[dstIndex] = sample;
                }
            }
        }
    }

    // Cook height field
    MemoryWriteStream outputStream;
    if (CollisionCooking::CookHeightField(heightFieldSize, heightFieldSize, heightFieldData, outputStream))
        return true;

    // Write results
    collisionData->Resize(sizeof(TerrainCollisionDataHeader) + outputStream.GetPosition(), false);
    const auto header = (TerrainCollisionDataHeader*)collisionData->Get();
    header->CheckOldMagicNumber = MAX_int32;
    header->Version = TerrainCollisionDataHeader::CurrentVersion;