森汉姆算法(AS3)－检测两点之间所经过的节点

为了把A*寻到的路径中一些没必要的节点去掉，可以用到森汉姆算法，如果两点之间经过的节点都是可走的，那就把这两个点连起来，最终拿到的路径就是比较平滑的了。

下面是算法实现：

 

public static function bresenham(x1:int, y1:int, x2:int, y2:int):Array

{

	var touched:Array = [];



	var steep:Boolean = Math.abs(y2 - y1) > Math.abs(x2 - x1);



	if (steep)

	{

		var tmp:int;

		tmp = x1;

		x1 = y1;

		y1 = tmp;

		tmp = x2;

		x2 = y2;

		y2 = tmp;

	}



	if (x1 > x2)

	{

		var x1_old:int = x1;

		var y1_old:int = y1;



		x1 = x2;

		x2 = x1_old;

		y1 = y2;

		y2 = y1_old;

	}



	var deltax:int = x2 - x1;

	var deltay:int = Math.abs(y2 - y1);

	var error:int = deltax / 2;

	var ystep:int;

	var y:int = y1;



	if (y1 < y2)

	{

		ystep = 1;

	}

	else

	{

		ystep = -1;

	}



	for (var x:int = x1; x <= x2; ++x)

	{

		if (steep)

		{

			touched.push(new Point(y, x));

		}

		else

		{

			touched.push(new Point(x, y));

		}

		error = error - deltay;

		if (error < 0)

		{

			y = y + ystep;

			error = error + deltax;

		}

	}

	

	return touched;

}

 

一些资料：http://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm