Function ModifyCollision

Source/Engine/Terrain/TerrainPatch.cpp:738–819

}

bool ModifyCollision(TerrainDataUpdateInfo& info, TextureBase::InitData* initData, int32 collisionLod, const Int2& modifiedOffset, const Int2& modifiedSize, void* heightField)
{
    info.GetSplatMaps();
    PROFILE_CPU_NAMED("Terrain.ModifyCollision");

    // Prepare data
    const Vector2 modifiedOffsetRatio((float)modifiedOffset.X / info.HeightmapSize, (float)modifiedOffset.Y / info.HeightmapSize);
    const Vector2 modifiedSizeRatio((float)modifiedSize.X / info.HeightmapSize, (float)modifiedSize.Y / info.HeightmapSize);
    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 Int2 samplesOffset(Vector2::Floor(modifiedOffsetRatio * (float)heightFieldSize));
    Int2 samplesSize(Vector2::Ceil(modifiedSizeRatio * (float)heightFieldSize));
    samplesSize.X = Math::Max(samplesSize.X, 1);
    samplesSize.Y = Math::Max(samplesSize.Y, 1);
    Int2 samplesEnd = samplesOffset + samplesSize;
    samplesEnd.X = Math::Min(samplesEnd.X, heightFieldSize);
    samplesEnd.Y = Math::Min(samplesEnd.Y, heightFieldSize);

    // Allocate data
    const int32 heightFieldDataLength = samplesSize.X * samplesSize.Y;
    GET_TERRAIN_SCRATCH_BUFFER(heightFieldData, info.HeightmapLength, PhysicsBackend::HeightFieldSample);
    PhysicsBackend::HeightFieldSample sample;
    Platform::MemoryClear(&sample, sizeof(PhysicsBackend::HeightFieldSample));
    Platform::MemoryClear(heightFieldData, sizeof(PhysicsBackend::HeightFieldSample) * heightFieldDataLength);

    // 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;
        if (chunkStartX >= samplesEnd.X || chunkStartX + vertexCountEdgeMip < samplesOffset.X)
            continue; // Skip unmodified chunks

        for (int32 chunkZ = 0; chunkZ < Terrain::ChunksCountEdge; chunkZ++)
        {
            const int32 chunkTextureZ = chunkZ * vertexCountEdgeMip;
            const int32 chunkStartZ = chunkZ * heightFieldChunkSize;
            if (chunkStartZ >= samplesEnd.Y || chunkStartZ + vertexCountEdgeMip < samplesOffset.Y)
                continue; // Skip unmodified chunks

            // TODO: adjust loop range to reduce iterations count for edge cases (skip checking unmodified samples)
            for (int32 z = 0; z < vertexCountEdgeMip; z++)
            {
                const int32 heightmapZ = chunkStartZ + z;
                const int32 heightmapLocalZ = heightmapZ - samplesOffset.Y;
                if (heightmapLocalZ < 0 || heightmapLocalZ >= samplesSize.Y)
                    continue; // Skip unmodified columns

                // TODO: adjust loop range to reduce iterations count for edge cases (skip checking unmodified samples)
                for (int32 x = 0; x < vertexCountEdgeMip; x++)
                {
                    const int32 heightmapX = chunkStartX + x;
                    const int32 heightmapLocalX = heightmapX - samplesOffset.X;