代码改变世界

速度向量之双轴速度

2011-12-10 13:25 by LoujaDy, ... 阅读, ... 评论, 收藏, 编辑

源码

//获取到舞台
var canvas=document.getElementById("stage");
//舞台2d绘图接口
var context=canvas.getContext("2d");
//获取中心点置
var centerX=canvas.width/2;
var centerY=canvas.height/2;
//在舞台上画一条马路
context.lineWidth = 2;
context.strokeStyle = "#ff0000";
context.beginPath();
context.moveTo(0,centerY+2);
context.lineTo(centerX*2,centerY+2);
                   context.stroke();
                   context.closePath();
                   /**
                    * 向量对象
                    
*/
                   var Vector2d=function(x,y)
                   {
this.x=x;
this.y=y;
                   } 
                   /**
                    * 球对象
                    
*/
                   var Ball=function(x,y,radius,color)
                   {
//球的中心点位置
this.x=x;
this.y=y;
//球的半径
this.radius=radius;
//球的颜色
this.color=color;
//球的边框颜色
context.strokeStyle = color;
//球体颜色
context.fillStyle=color; 
/**
        * 绘制球
        
*/ 
this.draw=function()
{
context.beginPath(); 
                           context.arc(this.x, this.y, this.radius, 0, 2 * Math.PI, false); 
                           context.fill(); 
                           context.stroke();
                           context.closePath();
}
                   } 
                   //球的半径 
                   var rd=20;
                   //创建一个球对象,让球在马路的最左边
                   var ball=new Ball(rd+1,centerY-rd-1,rd,"#ccc"); 
                   var ballVector=null;
                   //显示球
                   ball.draw(); 
                   /**
                    * 开始按钮事件
                    
*/
                   function Run()
                   { 
                        //球运行的速度[x轴速度是3,y轴速度是-1]
                         ballVector=new Vector2d(3,-1); 
                   } 
     //动画
                       var drawAsync = eval(Jscex.compile("async", function () {
                                   while(true)
                                   {
if(ballVector!=null)
{
//清空马路上方的区域
        context.clearRect(0,0, centerX*2, centerY);
        //球双向移动
                                        ball.x+=ballVector.x;
                                        ball.y+=ballVector.y;
                                        //如果球出界了还原位置
                                        if(ball.y+rd<=0)
                                        {
ball.x=rd+1;
ball.y=centerY-rd-1;
                                        }
                                        ball.draw();
}
                                        $await(Jscex.Async.sleep(1000/60));
                                    }
                       }));
                       drawAsync().start();

 作者:Louja

出处:http://loujady.cnblogs.com
本文版权归作者和博客园共有,欢迎转载,但未经作者同意必须保留此声明,且在文章页面给出原文连接,否则保留追究法律责任的权利。