bazier.rar_elliptic curves

//////////////////////////////////////////////////////////////////////////////////// //代码由roading编写 //根据基点信息计算二次和三次Bezier曲线的点序列 import flash.geom.Point; class Bezier { var p1:Point; var p2:Point; var p3:Point; var p4:Point; var tp1:Point; var tp2:Point; var tp3:Point; var tp4:Point; var count:Number; //init Bezier data function Bezier(pt1:Point,pt2:Point,pt3:Point,pt4:Point) { if(arguments.length < 3) return; if(arguments.length == 3){ count = 3; } else { count = 4; } p1 = pt1; p2 = pt2; p3 = pt3; p4 = pt4; } // calculate point function calculate(t:Number) { var temp:Point; //(1-t)*(1-t)*p1+2*t*(1-t)*p2+t*t*p3 //Math.pow(1-t,3)*p1+3*t*(1-t)*(1-t)*p2+3*t*t*(1-t)*p3+Math.pow(t,3)*p4 //二次Bezier if(count == 3) { tp1 = multiply((1-t)*(1-t),p1); tp2 = multiply(2*t*(1-t),p2); tp3 = multiply(t*t,p3); temp = p1.add(tp2); temp = temp.add(tp3); } else //三次Bezier { tp1 = multiply(Math.pow(1-t,3),p1); tp2 = multiply(3*t*(1-t)*(1-t),p2); tp3 = multiply(3*t*t*(1-t),p3); tp4 = multiply(Math.pow(t,3),p4); temp = tp1.add(tp2); temp = temp.add(tp3); temp = temp.add(tp4); } return temp; } function multiply(num:Number,p:Point):Point { var temp:Point = new Point(); temp.x = p.x*num; temp.y = p.y*num; return temp; } } //------------------------------------------------------------------------------------------------------------ 使用方法: //根据构造函数的参数来确定二次还是三次的Bezier,第一和最后一个参数是基本点,中间的是控制点... //50,400,140,20,400,40,635,420 import flash.geom.Point; var m1 = new Point(50,400); var m2 = new Point(140,20); var m3 = new Point(400,40); var m4 = new Point(635,420); var b = new Bezier(m1,m2,m3,m4); for(var i=0;i<=100;i++) { trace(b.calculate(i/100)); } //-------------------------------------------------------- //trace结果