as3绘制抛物线(二)

上一篇文章，只是简单的求出了抛物线的坐标，而且也不够灵活。如果只是单纯的画线，使用as3自带的curveTo(二次贝塞尔曲线)就已经足够了。

二次贝塞尔曲线演示动画 t in [0, 1]  (图片来源于wiki贝塞尔曲线>>)

 

下面的例子，根据鼠标的位置，绘制经过指定起始点、结束点和鼠标位置的曲线。

package

   2: {

import flash.display.Sprite;

import flash.events.Event;

   5:     

/**

     * ...

     * @author Meteoric

     */

extends Sprite

  11:     {

private var x0:Number = 100;

private var y0:Number = 400;

private var x1:Number;

private var y1:Number;

private var x2:Number = 500;

private var y2:Number = 400;

  18:         

public function DrawCurveDemo() 

  20:         {

  21:             initView();

  22:         }

  23:         

void

  25:         {

  26:             addEventListener(Event.ENTER_FRAME, onEnterFrameHandler);

  27:             

  28:             onEnterFrameHandler();

  29:         }

  30:         

void 

  32:         {

  33:             x1 = mouseX;

  34:             y1 = mouseY;

  35:             

  36:             graphics.clear();

  37:             graphics.lineStyle(2, 0x3399cc);

  38:             graphics.moveTo(x0, y0);

  39:             graphics.curveTo(x1, y1, x2, y2);

  40:         }

  41:         

  42:     }

  43:  

  44: }