检测点是否在三角形内

数据类：

package
{
	import flash.geom.Point;
	/**
	 * 三角形数据类
	 * @author Jave.Lin
	 */
	public class Triangle
	{
		public var p1:Point;
		public var p2:Point;
		public var p3:Point;
		
		public function Triangle($p1:Point,$p2:Point,$p3:Point)
		{
			p1=$p1;
			p2=$p2;
			p3=$p3;
		}
		
		public function checkPointIn(tp:Point):Boolean
		{
			var area:Number=getArea();
			var targetThreeTimesArea:Number=0;
			targetThreeTimesArea+=getAreaByPoints(tp,p1,p2);
			targetThreeTimesArea+=getAreaByPoints(tp,p2,p3);
			targetThreeTimesArea+=getAreaByPoints(tp,p3,p1);
			return targetThreeTimesArea==area||Math.abs(targetThreeTimesArea-area)