/// <summary>
/// The constructor of the grid spatial partition algorithm
/// </summary>
/// <param name="maxX">The max x value</param>
/// <param name="maxY">The max y value</param>
/// <param name="areaSize">The Size of a grid area</param>
/// <param name="xOffset"></param>
/// <param name="yOffset"></param>
/// <param name="distance"></param>
public Grid2(int maxX, int maxY, int areaSize, int xOffset, int yOffset, int distance = 0)
{
if (distance > areaSize)
{
throw new ArgumentException("Distance shouldn't be larger then area size:");
}
this.maxX = maxX + xOffset;
this.maxY = maxY + yOffset;
this.areaSize = areaSize;
this.xOffset = xOffset;
this.yOffset = yOffset;
this.distance = distance;
maxXAreaIndex = this.maxX / areaSize;
maxYAreaIndex = this.maxY / areaSize;
entityAreas = new GridEntity[maxXAreaIndex][];
for (var i = 0; i < maxXAreaIndex; i++)
{
entityAreas[i] = new GridEntity[maxYAreaIndex];
for (var j = 0; j < maxYAreaIndex; j++)
{
entityAreas[i][j] = null;
}
}
}
public override void Add(IEntity entity)
{
var entityPositionX = entity.Position.X + xOffset;
var entityPositionY = entity.Position.Y + yOffset;
var range = entity.Range;
// we actually have a circle but we use this as a square for performance reasons
// we now find all areas that are inside this square
var squareMaxX = entityPositionX + range;
var squareMaxY = entityPositionY + range;
var squareMinX = entityPositionX - range;
var squareMinY = entityPositionY - range;
// We first use starting y index to start filling
var startingYIndex = (int)Math.Floor(squareMinY / areaSize);
// We now define starting x index to start filling
var startingXIndex = (int)Math.Floor(squareMinX / areaSize);
// Also define stopping indexes
var stoppingYIndex =
(int)Math.Ceiling(squareMaxY / areaSize);
var stoppingXIndex =
(int)Math.Ceiling(squareMaxX / areaSize);
if (startingXIndex < 0)
{
return;
}
if (startingYIndex < 0)
{
return;
}
if (stoppingXIndex >= maxXAreaIndex)
{
return;
}
if (stoppingYIndex >= maxYAreaIndex)
{
return;
}
// Now fill all areas from min {x, y} to max {x, y}
for (var j = startingXIndex; j <= stoppingXIndex; j++)
{
var xArr = entityAreas[j];
for (var i = startingYIndex; i <= stoppingYIndex; i++)
{
var gridEntity = new GridEntity(entity, null, xArr[i]);
xArr[i] = gridEntity;
if (gridEntity.Next != null)
{
gridEntity.Next.Prev = gridEntity;
}
}
}
}