void RecursivelyPropagateLight(World world, BlockPosition blockPosition, byte incomingLightValue)
{
TotalNumberOfRecursions++;
NumberOfRecursions++;
if (incomingLightValue < 1)
{
return;
}
var block = world.GetBlockAt(blockPosition);
if (block.LightLevel >= incomingLightValue)
{
return;
}
if (!block.CanPropagateLight)
{
return;
}
world.SetLightLevel(blockPosition, incomingLightValue);
//Trace.WriteLine(string.Format("Replaced light value {0} with {1} at {2}", block.LightLevel, incomingLightValue, blockPosition));
var outgoingLightLevel = (byte)(incomingLightValue - 1);
// TODO: right now this is a depth-first fill. We really need to do a breadth-first fill so that blocks gets filled
// first with the highest possible levels of light and we don't spend time overwriting lower levels from long recursion
// chains that doubled back with higher levels from shorter recursion chains.
// http://en.wikipedia.org/wiki/Iterative_deepening
// It would probably be smart to get some unit tests going before messing with this too much.
// It might also be interesting to do iterative deepening across the whole chunk so that multiple
// sunlit blocks contributing to a large dark space fill it in cooperatively rather than the first
// block flood-filling the whole space, then the second doing the same with slightly different values.
// That would probably not be a net win but it's worth thinking about. We could do a first pass on all
// sunlit blocks and make a list of just the ones that managed to propogate light somewhere, then do
// iterative deepening on just those.
if (outgoingLightLevel > 0)
{
RecursivelyPropagateLight(world, blockPosition.Left, outgoingLightLevel);
RecursivelyPropagateLight(world, blockPosition.Right, outgoingLightLevel);
RecursivelyPropagateLight(world, blockPosition.Up, outgoingLightLevel);
RecursivelyPropagateLight(world, blockPosition.Down, outgoingLightLevel);
RecursivelyPropagateLight(world, blockPosition.Front, outgoingLightLevel);
RecursivelyPropagateLight(world, blockPosition.Back, outgoingLightLevel);
}
}
