AS 3.0学习笔记
最近学习 as3.0，虽然 感觉不如Silverlight 好使，但是有些方面还是不错的，各有各优点吧。但是今天 学习遇到了个问题，从书上面照到打的一段代码运行无果，没有任何效果，最后拷贝代码下来运行也是这样，试了好久，找到原因，就是因为把stage.scaleMode 设成了 NoScale .猜想原因是初始化的时候他的舞台效果只能够定义一次吧，整个程序就只有两个类，像在一个棋盘上面画围棋，下面这个是ball类
package
{
import flash.display.Sprite;
public class Ball extends Sprite
{
private var _Color:uint;
private var _Radius:Number;
private var _vx:Number=0;
private var _vy:Number=0;
public function Ball(radius:Number,color:uint=0xffffff)
{
this._Radius=radius;
this._Color=color;
}
private function Draw():void
{
this.graphics.lineStyle(0);
this.graphics.beginFill(0xcccccc);
this.graphics.drawCircle(0,0,radius);
this.graphics.endFill();
}
public function Update():void
{
x+=this._vx;
y+=this._vy;
}
public function set Color(value:uint):void
{
this._Color=value;
Draw();
}
public function get Color():uint
{
return this._Color;
}
public function get radius():Number
{
return this._Radius;
}
public function set VX(value:Number):void
{
this._vx=value;
}
public function get VX():Number
{
return this._vx;
}
public function set VY(value:Number):void
{
this._vy=value;
}
public function get VY():Number
{
return this._vy;
}
}
}
下面这个类是 主程序:
package
{
import flash.display.Sprite;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
public class TEST4 extends Sprite
{
private const GRID_SIZE: Number = 50;
private const RADIUS: Number = 25;
private var _balls: Array;
private var _grid: Array;
private var _numBalls: int = 100;
private var _numChecks: int = 0;
public function TEST4()
{
stage.align = StageAlign.TOP_LEFT;
stage.scaleMode = StageScaleMode.SHOW_ALL;
makeBalls();
makeGrid();
drawGrid();
assignBallsToGrid();
checkGrid();
}
// 剩余的函数等下一一介绍
private function makeBalls(): void
{
_balls = new Array();
for(var i: int=0; i < _numBalls; i++)
{
// 创建出一个球，然后把它加入显示列表以及数组
var ball: Ball = new Ball(RADIUS);
ball.x = Math.random() * stage.stageWidth;
ball.y = Math.random() * stage.stageHeight;
addChild(ball);
_balls.push(ball);
}
}
private function makeGrid(): void
{
_grid = new Array();
// 场景宽度 / 格子大小 = 网格列数
for(var i: int=0; i < stage.stageWidth / GRID_SIZE; i++)
{
_grid[ i ] = new Array();
// 场景高度 / 格子大小 = 网格行数
for(var j: int=0; j < stage.stageHeight / GRID_SIZE; j++)
{
_grid[ i ][j] = new Array();
}
}
}
private function drawGrid(): void
{
// 画出行列线
graphics.lineStyle(0, .5);
for(var i: int=0; i <= stage.stageWidth; i+=GRID_SIZE)
{
graphics.moveTo(i, 0);
graphics.lineTo(i, stage.stageHeight);
trace(this.stage.stageWidth);
}
for(i=0; i <= stage.stageHeight; i+=GRID_SIZE)
{
graphics.moveTo(0, i);
graphics.lineTo(stage.stageWidth, i);
}
}
private function assignBallsToGrid(): void
{
for(var i: int=0; i < _numBalls; i++)
{
// 球的位置除以格子大小，得到该球所在网格的行列数
var ball: Ball = _balls[ i ] as Ball;
var xpos: int = Math.floor(ball.x / GRID_SIZE);
var ypos: int = Math.floor(ball.y / GRID_SIZE);
(_grid[ xpos ][ ypos ] as Array).push(ball);
}
}
private function checkGrid(): void
{
for(var i: int=0; i < _grid.length; i++)
{
for(var j: int=0; j < _grid[ i ].length; j++)
{
// 检测第一个格子内的对象间是否发生碰撞
checkOneCell(i, j);
checkTwoCells(i, j, i+1, j); // 右边的格子
checkTwoCells(i, j, i-1, j+1); // 左下角的格子
checkTwoCells(i, j, i, j+1); // 下边的格子
checkTwoCells(i, j, i+1, j+1); // 右下角的格子
}
}
}
private function checkOneCell(x: int, y: int): void
{
// 检测当前格子内所有的对象
var cell:Array = _grid[ x ][ y ] as Array;
for(var i: int=0; i < cell.length-1; i++)
{
var ballA: Ball = cell[ i ] as Ball;
for(var j: int=i+1; j < cell.length; j++)
{
var ballB: Ball = cell[ j ] as Ball;
checkCollision(ballA, ballB);
}
}
}
private function checkTwoCells(x1: int, y1: int, x2: int, y2: int): void
{
// 确保要检测的格子存在
if(x2 < 0) return;
if(x2 >= _grid.length) return;
if(y2 >= _grid[ x2 ].length) return;
var cell0:Array = _grid[ x1 ][ y1 ] as Array;
var cell1:Array = _grid[ x2 ][ y2 ] as Array;
// 检测当前格子和邻接格子内所有的对象
for(var i: int=0; i < cell0.length; i++)
{
var ballA: Ball = cell0[ i ] as Ball;
for(var j: int=0; j < cell1.length; j++)
{
var ballB: Ball = cell1[ j ] as Ball;
checkCollision(ballA, ballB);
}
}
}
private function checkCollision(ballA: Ball, ballB: Ball):void
{
// 判断距离的碰撞检测
_numChecks++;
var dx: Number = ballB.x - ballA.x;
var dy: Number = ballB.y - ballA.y;
var dist: Number = Math.sqrt(dx * dx + dy * dy);
if(dist < ballA.radius + ballB.radius)
{
ballA.color = 0xff0000;
ballB.color = 0xff0000;
}
}
}
}
这是好的。但是在构造函数里面，如果把 stage.scaleMode = StageScaleMode.SHOW_ALL;高成NoScale,就会有问题，只显示一个小球的一部分。