向量类

Flex绘制矢量图形时，经常用到一些小算法，比如求交点、求垂线……有的还很烦琐。如果只用Point类进行操作的话，那会是一件非常痛苦的事，而改用向量运算，则可以大大减少运算量，也使得程序条理更清晰，便于理解。于是自编（当然离不开COPY大虾的程序啦）向量类V2D.as如下:

package//注意类中所有角度均为弧度{public class V2D{public var x:Number;public var y:Number;public function V2D(x:Number=0, y:Number=0){this.x = x;this.y = y;}public static function plus(v1:V2D, v2:V2D):V2D//向量V1+V2{return new V2D(v1.x+v2.x, v1.y+v2.y);}public static function minus(v1:V2D, v2:V2D):V2D//向量V1-V2{return new V2D(v1.x-v2.x, v1.y-v2.y);}public function reset(xx:Number, yy:Number):void//向量重新赋值{this.x = xx;this.y = yy;}public function clone():V2D//克隆{return new V2D(x,y);}public function selfPlus(v:V2D):void//向量加法{x += v.x;y += v.y;}public function selMinus(v:V2D):void//向量减法{x -= v.x;y -= v.y;}public function negate():void//向量旋转180度{x = -x;y = -y;}public function scale(s:Number):void//向量缩放s倍，改变向量的大小{x *= s;y *= s;}public function length():Number//向量的模{return Math.sqrt(x*x + y*y);}public function setLength(len:Number):void//设置向量的长度{var len0:Number = length();if(len0){scale(len/len0);}else{x = len;}}public function getTangle():Number//向量角度{return Math.atan2(y,x);}public function setAngle(ang:Number):void//改变向量角度，保持向量原有长度{var len0:Number = this.length();x = len0 * Math.cos(ang);y = len0 * Math.sin(ang);}public function rotate(ang:Number):void//向里旋转ang弧度{var ca:Number = Math.cos(ang);var sa:Number = Math.sin(ang);var rx:Number = x*ca - y*sa;var ry:Number = x*sa + y*ca;this.x = rx;this.y = ry;}public function dot(v:V2D):Number//向量点乘{return x*v.x + y*v.y;}public function getNormalS():V2D//得到顺时针方向的法向量{return new V2D(y,-x);}public function getNormalN():V2D//逆时针方向的法向量{return new V2D(-y,x);}public function angleBetween(v:V2D):Number//计算两个向量之间的夹角{var dp:Number = dot(v);var cosAngle:Number = dp / (length()*v.length());return Math.acos(cosAngle);}}}