Flash/Flex学习笔记(31)：对象拖拽与投掷

对象拖拽：

这其实就是以前所学知识：Flash/Flex学习笔记(13)：对象拖动(startDrag/stopDrag) +Flash/Flex学习笔记(23)：运动学原理的综合运用，要提一下的是下面代码中对于EnterFrame的添加与移除操作

    
            01
            package {
        
            02
                import flash.display.Sprite;
        
            03
                import flash.display.StageAlign;
        
            04
                import flash.display.StageScaleMode;
        
            05
                import flash.events.Event;
        
            06
                import flash.events.MouseEvent;
        
            07
                import flash.ui.Mouse;
        
            08
                import flash.ui.MouseCursor;
        
            09
                 
            10
                public class Bouncing2 extends Sprite {
        
            11
                     
            12
                    private var ball:Ball;
        
            13
                    private var vx:Number;
        
            14
                    private var vy:Number;
        
            15
                    private var bounce:Number=-0.8;//反弹速度百分比
        
            16
                    private var gravity:Number=0.9;//重力加速度百分比
        
            17
                    private var frictionX:Number=0.98;//摩擦力因子--水平方向
        
            18
                    private var frictionY:Number=0.99;//摩擦力因子--垂直方向
        
            19
                     
            20
                    public function Bouncing2() {
        
            21
                        init();
        
            22
                    }
        
            23
                     
            24
                    private function init():void {
        
            25
                        stage.scaleMode=StageScaleMode.NO_SCALE;
        
            26
                        stage.align=StageAlign.TOP_LEFT;
        
            27
                        ball=new Ball(20)  ;
        
            28
                        ball.x=stage.stageWidth/2;
        
            29
                        ball.y=stage.stageHeight/2;
        
            30
                        vx=(Math.random()*2-1) * 20;
        
            31
                        vy=-10;
        
            32
                        addChild(ball);
        
            33
                        ball.addEventListener(MouseEvent.MOUSE_DOWN,MouseDownHandler);
        
            34
                        ball.addEventListener(MouseEvent.MOUSE_OVER,function(){ Mouse.cursor = MouseCursor.HAND;});
        
            35
                        ball.addEventListener(MouseEvent.MOUSE_OUT,function(){ Mouse.cursor = MouseCursor.AUTO;});
        
            36
                        addEventListener(Event.ENTER_FRAME,EnterFrameHandler);
        
            37
                    }
        
            38
                    private function EnterFrameHandler(event:Event):void {
        
            39
                        vy+=gravity; //加入重力加速度，所以肯定会向下掉
        
            40
                        vx *= frictionX; //加入摩擦力，所以最终会停下来
        
            41
                        vy *= frictionY;
        
            42
                        ball.x+=vx;//产生移动
        
            43
                        ball.y+=vy;
        
            44
                         
            45
                        var left:Number=0;
        
            46
                        var right:Number=stage.stageWidth;
        
            47
                        var top:Number=0;
        
            48
                        var bottom:Number=stage.stageHeight;
        
            49
                         
            50
                        //水平方向边界检测
        
            51
                        if (ball.x+ball.radius>right) {
        
            52
                            ball.x=right-ball.radius;
        
            53
                            vx*=bounce;
        
            54
                        } else if (ball.x - ball.radius < left) {
        
            55
                            ball.x=left+ball.radius;
        
            56
                            vx*=bounce;
        
            57
                        }
        
            58
                         
            59
                        //垂直方向边界检测
        
            60
                        if (ball.y+ball.radius>bottom) {
        
            61
                            ball.y=bottom-ball.radius;
        
            62
                            vy*=bounce;
        
            63
                        } else if (ball.y - ball.radius < top) {
        
            64
                            ball.y=top+ball.radius;
        
            65
                            vy*=bounce;
        
            66
                        }
        
            67
                    }
        
            68
                    private function MouseDownHandler(e:MouseEvent):void {
        
            69
                        stage.addEventListener(MouseEvent.MOUSE_UP,MouseUpHandler);
        
            70
                        ball.startDrag();
        
            71
                        removeEventListener(Event.ENTER_FRAME,EnterFrameHandler);//移除EnterFrame事件，否则在拖动过程中，小球还在不断下掉
        
            72
                    }
        
            73
                    private function MouseUpHandler(e:MouseEvent):void {
        
            74
                        stage.removeEventListener(MouseEvent.MOUSE_UP,MouseUpHandler);
        
            75
                        ball.stopDrag();
        
            76
                        addEventListener(Event.ENTER_FRAME,EnterFrameHandler);//拖动完成后，恢复EnterFrame事件监听，以便小球能不断运动
        
            77
                    }
        
            78
                }
        
            79
            }

对象投掷：

在上面的代码中，鼠标的拖拽只影响了小球的y坐标(注：指对运动方面的影响)，即仅相当于举高了小球。而投掷则意味着：在鼠标松开小球的那一瞬间，小球也应该具备有一定的出口速度(即鼠标最终的移动速度)。Flash中每一帧对应的时间基本上是相同的，可以认为这就是物理中的“单位时间”，根据刚才对投掷概念的理解，只要代码能得知在鼠标松开小球的最后一帧，小球在x,y轴方向的位移，即为小球的出口x,y轴速度.

    
            01
            package {
        
            02
                import flash.display.Sprite;
        
            03
                import flash.display.StageAlign;
        
            04
                import flash.display.StageScaleMode;
        
            05
                import flash.events.Event;
        
            06
                import flash.events.MouseEvent;
        
            07
                import flash.ui.MouseCursor;
        
            08
                import flash.ui.Mouse;
        
            09
                 
            10
                public class Throwing extends Sprite {
        
            11
                     
            12
                    private var ball:Ball;
        
            13
                    private var vx:Number;
        
            14
                    private var vy:Number;
        
            15
                    private var bounce:Number=-0.8;
        
            16
                    private var gravity:Number=0.75;
        
            17
                    private var frictionX:Number = 0.98;
        
            18
                    private var frictionY:Number = 0.99;
        
            19
                    private var oldX:Number;
        
            20
                    private var oldY:Number;
        
            21
                     
            22
                    public function Throwing() {
        
            23
                        init();
        
            24
                    }
        
            25
                     
            26
                    private function init():void {
        
            27
                        stage.scaleMode=StageScaleMode.NO_SCALE;
        
            28
                        stage.align=StageAlign.TOP_LEFT;
        
            29
                        ball = new Ball(30);
        
            30
                        ball.x = stage.stageWidth/2;
        
            31
                        ball.y = stage.stageHeight/2;
        
            32
                        vx = Math.random()*10-5;
        
            33
                        vy = -10;
        
            34
                        addChild(ball);
        
            35
                        ball.addEventListener(MouseEvent.MOUSE_DOWN, MouseDownHandler);
        
            36
                        ball.addEventListener(MouseEvent.MOUSE_OVER,function(){Mouse.cursor = MouseCursor.HAND;});
        
            37
                        ball.addEventListener(MouseEvent.MOUSE_OUT,function(){Mouse.cursor = MouseCursor.AUTO;});
        
            38
                        addEventListener(Event.ENTER_FRAME, EnterFrameHandler);
        
            39
                    }
        
            40
                     
            41
                    private function MouseDownHandler(event:MouseEvent):void {
        
            42
                        oldX = ball.x;
        
            43
                        oldY = ball.y;
        
            44
                        stage.addEventListener(MouseEvent.MOUSE_UP, MouseUpHandler);
        
            45
                        ball.startDrag();
        
            46
                        removeEventListener(Event.ENTER_FRAME, EnterFrameHandler);
        
            47
                        addEventListener(Event.ENTER_FRAME, TrackVelocity);
        
            48
                    }
        
            49
                     
            50
                    private function EnterFrameHandler(event:Event):void {
        
            51
                        vy += gravity;
        
            52
                        vx *= frictionX;
        
            53
                        vy *= frictionY;
        
            54
                        ball.x += vx;
        
            55
                        ball.y += vy;
        
            56
                        var left:Number=0;
        
            57
                        var right:Number=stage.stageWidth;
        
            58
                        var top:Number=0;
        
            59
                        var bottom:Number=stage.stageHeight;
        
            60
                        if (ball.x+ball.radius>right) {
        
            61
                            ball.x=right-ball.radius;
        
            62
                            vx*=bounce;
        
            63
                        } else if (ball.x - ball.radius < left) {
        
            64
                             
            65
                            ball.x=left+ball.radius;
        
            66
                            vx*=bounce;
        
            67
                        }
        
            68
                        if (ball.y+ball.radius>bottom) {
        
            69
                            ball.y=bottom-ball.radius;
        
            70
                            vy*=bounce;
        
            71
                        } else if (ball.y - ball.radius < top) {
        
            72
                            ball.y=top+ball.radius;
        
            73
                            vy*=bounce;
        
            74
                        }
        
            75
                    }
        
            76
                     
            77
                    //跟踪每一帧小球的速度(坐标位置)
        
            78
                    private function TrackVelocity(event:Event):void {
        
            79
                        vx = ball.x-oldX;
        
            80
                        vy = ball.y-oldY;
        
            81
                        oldX = ball.x;
        
            82
                        oldY = ball.y;
        
            83
                    }
        
            84
                     
            85
                    private function MouseUpHandler(e:MouseEvent):void {
        
            86
                        stage.removeEventListener(MouseEvent.MOUSE_UP, MouseUpHandler);
        
            87
                        ball.stopDrag();
        
            88
                        removeEventListener(Event.ENTER_FRAME, TrackVelocity);
        
            89
                        addEventListener(Event.ENTER_FRAME, EnterFrameHandler);
        
            90
                    }
        
            91
                     
            92
                     
            93
                }
        
            94
            }

作者：菩提树下的杨过
出处：http://yjmyzz.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段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。

posted on 2010-11-17 16:40 aiaiwoo 阅读(95) 评论(0) 编辑收藏所属分类: AC3/FLEX

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Flash/Flex学习笔记(31)：对象拖拽与投掷

Flash/Flex学习笔记(31)：对象拖拽与投掷

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