public unsafe World DownSample(int extraLods, out int voxelCount)
{
World subWorld = new World(dimensions, lod + extraLods);
World thisWorld = this;
int step = 1 << subWorld.lod;
int totalVoxels = 0;
// parallelize downsampling on the X-axis
System.Threading.Tasks.Parallel.For(0, dimensions.x / step, (int i) =>
{
int yVoxels = subWorld.dimensions.y >> subWorld.lod;
RLEElement[] elementBuffer = new RLEElement[yVoxels];
WorldBuilder.RLEColumnBuilder builder = new WorldBuilder.RLEColumnBuilder();
int x = i * step;
for (int z = 0; z < subWorld.dimensions.z; z += step)
{
// downsample a {step, step} grid of columns into one
RLEColumn downSampled = thisWorld.DownSampleColumn(x, z, elementBuffer, extraLods, ref builder, ref totalVoxels, ref subWorld.Storage);
*subWorld.Storage.GetColumnPointer(subWorld.GetIndexKnownInBounds(int2(x, z))) = downSampled;
}
});
voxelCount = totalVoxels;
return(subWorld);
}
/// <summary>
/// Output a column of data into the columnbuilder; after doing this with all columns the builder will be resolved to a new, merged column
/// </summary>
unsafe void DownSamplePartial(int x, int z, int extraLods, ref WorldBuilder.RLEColumnBuilder columnBuilder)
{
RLEColumn column = *Storage.GetColumnPointer(GetIndexKnownInBounds(int2(x, z)));
if (column.RunCount <= 0)
{
return;
}
int2 elementBounds = dimensions.y >> lod;
int nextLod = lod + extraLods;
ColorARGB32 *colorPointer = column.ColorPointer(ref Storage);
for (int run = 0; run < column.RunCount; run++)
{
RLEElement element = column.GetIndex(ref Storage, run);
elementBounds = int2(elementBounds.x - element.Length, elementBounds.x);
if (element.IsAir)
{
continue;
}
for (int i = 0; i < element.Length; i++)
{
int Y = elementBounds.x + i;
int colorIdx = element.ColorsIndex + element.Length - i - 1;
columnBuilder.SetVoxel(Y >> nextLod, colorPointer[colorIdx]);
}
}
}
// downsample a grid of columns into one column
public RLEColumn DownSampleColumn(int xStart, int zStart, RLEElement[] buffer, int extraLods, ref WorldBuilder.RLEColumnBuilder columnBuilder, ref int totalVoxels, ref WorldAllocator newStorage)
{
// lod 0 = 0, 1
// lod 1 = 0, 2
int stepSize = 1 << lod;
int steps = 1 << extraLods;
int nextVoxelCountY = (dimensions.y >> (lod + extraLods)) - 1;
columnBuilder.Clear();
for (int ix = 0; ix < steps; ix++)
{
int x = xStart + ix * stepSize;
for (int iz = 0; iz < steps; iz++)
{
int z = zStart + iz * stepSize;
DownSamplePartial(x, z, extraLods, ref columnBuilder);
}
}
return(columnBuilder.ToFinalColumn(1 << (lod + extraLods), (short)(nextVoxelCountY), buffer, ref totalVoxels, ref newStorage));
}
