public static async Task <Dictionary <Vector2Ushort, ZoneChunkFilledCellsCounter> > CalculateZoneChunks(
IQuadTreeNode quadTree,
int chunkSize,
Func <Task> callbackYieldIfOutOfTime)
{
// this is a heavy method so we will try to yield every few nodes to reduce the load
const int defaultCounterToYieldValue = 100;
var counterToYield = defaultCounterToYieldValue;
var dict = new Dictionary <Vector2Ushort, ZoneChunkFilledCellsCounter>();
if (false)
{
// slow algorithm (each tile added separately into the dictionary)
ZoneChunkFilledCellsCounter lastCounter = new ZoneChunkFilledCellsCounter(Vector2Ushort.Max);
foreach (var filledNode in quadTree.EnumerateFilledNodes())
{
var size = filledNode.Size;
var startPosition = filledNode.Position;
var endPosition = startPosition + new Vector2Ushort(size, size);
for (var y = startPosition.Y; y < endPosition.Y; y++)
{
for (var x = startPosition.X; x < endPosition.X; x++)
{
var chunkPosition = new Vector2Ushort((ushort)(x / chunkSize), (ushort)(y / chunkSize));
if (lastCounter.ChunkOffset == chunkPosition ||
dict.TryGetValue(chunkPosition, out lastCounter))
{
lastCounter.Count++;
}
else
{
lastCounter = new ZoneChunkFilledCellsCounter(chunkPosition)
{
Count = 1
};
dict[chunkPosition] = lastCounter;
}
}
}
}
}
// fast algorithm (each quad tree node can instantly fill each chunk)
foreach (var node in quadTree.EnumerateFilledNodes())
{
await YieldIfOutOfTime();
var nodeStartPosition = node.Position;
var startChunksOffset = new Vector2Ushort(
(ushort)(chunkSize * (nodeStartPosition.X / chunkSize)),
(ushort)(chunkSize * (nodeStartPosition.Y / chunkSize)));
var nodeSize = node.Size;
if (nodeSize == 1)
{
// short path
var chunkPosition = new Vector2Ushort(startChunksOffset.X, startChunksOffset.Y);
if (!dict.TryGetValue(chunkPosition, out var counter))
{
counter = new ZoneChunkFilledCellsCounter(chunkPosition);
dict[chunkPosition] = counter;
}
counter.Count++;
continue;
}
// long path (for nodes > 1*1 size)
var nodeEndPosition = nodeStartPosition.AddAndClamp(new Vector2Ushort(node.Size, node.Size));
var endChunksOffset = new Vector2Ushort(
(ushort)(chunkSize * Math.Ceiling(nodeEndPosition.X / (double)chunkSize)),
(ushort)(chunkSize * Math.Ceiling(nodeEndPosition.Y / (double)chunkSize)));
for (var chunkY = startChunksOffset.Y;
chunkY < endChunksOffset.Y;
chunkY = (ushort)(chunkY + chunkSize))
{
for (var chunkX = startChunksOffset.X;
chunkX < endChunksOffset.X;
chunkX = (ushort)(chunkX + chunkSize))
{
var chunkPosition = new Vector2Ushort(chunkX, chunkY);
var cellsCount = CalculateCellsCount(nodeStartPosition, nodeEndPosition, chunkX, chunkY, chunkSize);
if (!dict.TryGetValue(chunkPosition, out var counter))
{
counter = new ZoneChunkFilledCellsCounter(chunkPosition);
dict[chunkPosition] = counter;
}
counter.Count += cellsCount;
}
}
}
return(dict);
Task YieldIfOutOfTime()
{
if (--counterToYield > 0)
{
return(Task.CompletedTask);
}
counterToYield = defaultCounterToYieldValue;
return(callbackYieldIfOutOfTime());
}
}
