curvethru.as

来自「这是《Flash MX编程与创意实现》的源代码」· AS 代码 · 共 32 行

/*
  CurveThru v1.1
  Oct. 29, 2002
  (c) 2002 Robert Penner
  
  MovieClip methods to draw a quadratic bezier (three control points)
  through a given point..
  
  Dependencies: _xpen and _ypen movie clip properties (drawing_api_core_extensions.as)
  
  The _xpen and _ypen properties are discussed in Chapter 10 of 
  Robert Penner's Programming Macromedia Flash MX
  
  http://www.robertpenner.com/profmx
  http://www.amazon.com/exec/obidos/ASIN/0072223561/robertpennerc-20
*/


MovieClip.prototype.drawCurve3Pts = function (x1, y1, x2, y2, x3, y3) {
    var cx = 2*x2 - .5*(x1 + x3);
    var cy = 2*y2 - .5*(y1 + y3);
    this.moveTo (x1, y1);
    this.curveTo (cx, cy, x3, y3);
}; 

MovieClip.prototype.curveToThru = function (px, py, ax, ay) {
    var cx = 2*px - .5*(this._xpen + ax);
    var cy = 2*py - .5*(this._ypen + ay);
    this.curveTo (cx, cy, ax, ay);
};