[ActionScript 3.0] AS3 绘制任意三角形任意顶点到对边的高

  1 package
  2 {
  3     import flash.display.Shape;
  4     import flash.display.Sprite;
  5     import flash.events.MouseEvent;
  6     import flash.geom.Point;
  7     import flash.text.TextField;
  8     
  9     /**
 10      * @author Frost.Yen
 11      * @E-mail 871979853@qq.com
 12      * @create 2015-8-18 下午3:16:57
 13      *
 14      */
 15     [SWF(width="1024",height="768")]
 16     public class DrawTriangle extends Sprite
 17     {
 18         private var _pointArr:Array = [new Point(200,150),new Point(500,300),new Point(150,400)];
 19         private var _btn:TextField;
 20         private var _container:Sprite;
 21         private var _heightShape:Shape;
 22         private var _pointA:TextField;
 23         private var _pointB:TextField;
 24         private var _pointC:TextField;
 25         private var _pointD:TextField;
 26         
 27         public function DrawTriangle()
 28         {
 29             initViews();
 30             initEventListeners();
 31         }
 32         private function initViews():void
 33         {
 34             _container = new Sprite();
 35             _btn = new TextField();
 36             _heightShape = new Shape();
 37             _btn.selectable = false;
 38             _btn.border = true;
 39             _btn.htmlText = "点击随机生成";
 40             _btn.autoSize = "left";
 41             _btn.background = true;
 42             _btn.backgroundColor = 0xdddddd;
 43             _btn.x = 100;
 44             _btn.y = 100;
 45             _pointA = getText(_container);
 46             _pointB = getText(_container);
 47             _pointC = getText(_container);
 48             _pointD = getText(_container);
 49             this.addChild(_btn);
 50             this.addChild(_container);
 51             this.addChild(_heightShape);
 52         }
 53         private function initEventListeners():void
 54         {
 55             _btn.addEventListener(MouseEvent.CLICK,onCreatClick);
 56             _pointA.addEventListener(MouseEvent.CLICK,onGetHeight);
 57             _pointB.addEventListener(MouseEvent.CLICK,onGetHeight);
 58             _pointC.addEventListener(MouseEvent.CLICK,onGetHeight);
 59         }
 60         private function onCreatClick(e:MouseEvent):void
 61         {
 62             creatTriangle();
 63         }
 64         
 65         private function creatTriangle():void
 66         {
 67             _pointArr = [];
 68             for(var i:int = 0;i<3;i++){
 69                 var point:Point = new Point(Math.floor(Math.random()*400)+150,Math.floor(Math.random()*400+150));
 70                 _pointArr.push(point);
 71             }
 72             _pointArr.sortOn("y");
 73             _heightShape.graphics.clear();
 74             _container.graphics.clear();
 75             _container.graphics.lineStyle(2,0xff0000);
 76             _container.graphics.moveTo(_pointArr[0].x,_pointArr[0].y);
 77             _container.graphics.lineTo(_pointArr[1].x,_pointArr[1].y);
 78             _container.graphics.moveTo(_pointArr[1].x,_pointArr[1].y);
 79             _container.graphics.lineTo(_pointArr[2].x,_pointArr[2].y);
 80             _container.graphics.moveTo(_pointArr[2].x,_pointArr[2].y);
 81             _container.graphics.lineTo(_pointArr[0].x,_pointArr[0].y);
 82             setText(_pointD,"");
 83             setText(_pointA,"A("+_pointArr[0].x+","+_pointArr[0].y+")",_pointArr[0].x,_pointArr[0].y);
 84             setText(_pointB,"B("+_pointArr[1].x+","+_pointArr[1].y+")",_pointArr[1].x,_pointArr[1].y);
 85             setText(_pointC,"C("+_pointArr[2].x+","+_pointArr[2].y+")",_pointArr[2].x,_pointArr[2].y);
 86         }
 87         private function onGetHeight(e:MouseEvent):void
 88         {
 89             var point:Point;
 90             var start:Point;
 91             switch(e.currentTarget){
 92                 case _pointA:
 93                     point = getCrossoverByVertex(_pointArr[0],_pointArr[1],_pointArr[2]);
 94                     break;
 95                 case _pointB:
 96                     point = getCrossoverByVertex(_pointArr[1],_pointArr[0],_pointArr[2]);
 97                     break;
 98                 case _pointC:
 99                     point = getCrossoverByVertex(_pointArr[2],_pointArr[0],_pointArr[1]);
100                     break;
101             }
102             setText(_pointD,"C("+point.x+","+point.y+")",point.x,point.y);
103             
104         }
105         /**
106          * 获取顶点的高线与对边的交点
107          * @param    vertex 顶点
108          * @param    point1 三角形另外两点之一
109          * @param    point2 三角形另外两点之一
110          * @return
111          */
112         private function getCrossoverByVertex(vertex:Point,point1:Point,point2:Point):Point
113         {
114             var k1:Number;//顶点对角线的斜率（即A点对角线为BC）
115             var b1:Number;//顶点对角线的直线方程的常数
116             var k2:Number;//高所在直线的斜率
117             var b2:Number;//高所在直线方程的常数
118             var crossPoint:Point = new Point();//高线和顶点对角线的交点
119             k1 = (point2.y - point1.y)/(point2.x - point1.x);
120             b1 = point1.y - k1 * point1.x;
121             k2 = -1 / k1 ;
122             b2 = vertex.y-k2*vertex.x;
123             crossPoint.x = (b1 - b2)/(k2 - k1);
124             crossPoint.y = k1 * ((b1 - b2)/(k2 - k1)) + b1;
125             drawHeight(vertex,crossPoint);
126             return crossPoint;
127         }
128         private function drawHeight(start:Point,end:Point):void
129         {
130             _heightShape.graphics.clear();
131             _heightShape.graphics.lineStyle(2,0xff00ff);
132             _heightShape.graphics.moveTo(start.x,start.y);
133             _heightShape.graphics.lineTo(end.x,end.y);
134             _heightShape.graphics.endFill();
135         }
136         private function getText(parent:Sprite):TextField
137         {
138             var t:TextField = new TextField;
139             t.autoSize = "left";
140             t.selectable = false;
141             parent.addChild(t);
142             return t;
143         }
144         private function setText(t:TextField,text:String,x:Number=0,y:Number=0):void
145         {
146             t.text = text;
147             t.x = x;
148             t.y = y;
149         }
150     }
151 }