如何阻止扩展舞台的动画剪辑的边缘进入 AS3 中的舞台边界？

Posted 2023-02-16

【中文标题】如何阻止扩展舞台的动画剪辑的边缘进入 AS3 中的舞台边界？

【英文标题】：How do I stop the edge of movieclips that extend the stage from entering stage boundaries in AS3?

【发布时间】：2015-07-15 15:39:23

【问题描述】：

我有一个扩展舞台的背景图像，顶部和底部，其位置由补间图像的按键控制。我想根据图像的移动方式将图像的边缘停在舞台的顶部或底部。我希望这适用于“layers_mc”和“bg_img”。

这是我的代码

import flash.events.KeyboardEvent;
import fl.transitions.Tween;
import fl.transitions.easing.*;

stop();

var isUpPressed:Boolean = false;
var isDownPressed:Boolean = false;
var tweenDown:Tween;
var tweenUp:Tween;

stage.addEventListener(KeyboardEvent.KEY_DOWN,onKeyboardDown);
stage.addEventListener(KeyboardEvent.KEY_UP,onKeyboardUp);
stage.addEventListener(KeyboardEvent.KEY_DOWN,onKeyboardDown2);
stage.addEventListener(KeyboardEvent.KEY_UP,onKeyboardUp2);

    function onKeyboardDown(e:KeyboardEvent):void
    
        if (e.keyCode == Keyboard.DOWN)
        
            isDownPressed = true;
        

        if (e.keyCode == Keyboard.UP)
        
            isUpPressed = true;
        
    

    function onKeyboardUp(e:KeyboardEvent):void
    
        if (e.keyCode == Keyboard.DOWN)
        
            isDownPressed = false;
        

        if (e.keyCode == Keyboard.UP)
        
            isUpPressed = false;
        
    

    stage.addEventListener(Event.ENTER_FRAME,loop);

    function loop(event:Event):void
    

    var posit:Number = layers_mc.y;
    var xDown:Number = layers_mc.y - 200;
    var xUp:Number = layers_mc.y + 200;

        if (isDownPressed)
        
            tweenDown = new Tween(layers_mc, "y", Regular.easeOut, posit, xDown, 2, true);                
            trace(layers_mc.y);
        

        if (isUpPressed)
        
            tweenUp = new Tween(layers_mc, "y", Regular.easeOut, posit, xUp, 2, true);
            trace(layers_mc.y);
        
    

     function onKeyboardDown2(e:KeyboardEvent):void
    
        if (e.keyCode == Keyboard.DOWN)
        
            isDownPressed = true;
        

        if (e.keyCode == Keyboard.UP)
        
            isUpPressed = true;
        
    

    function onKeyboardUp2(e:KeyboardEvent):void
    
        if (e.keyCode == Keyboard.DOWN)
        
            isDownPressed = false;
        

        if (e.keyCode == Keyboard.UP)
        
            isUpPressed = false;
        
    

    stage.addEventListener(Event.ENTER_FRAME,loop2);

    function loop2(event:Event):void
    

    var posit2:Number = bg_img.y;
    var xDown2:Number = bg_img.y - 50;
    var xUp2:Number = bg_img.y + 50;

        if (isDownPressed)
        
            tweenDown = new Tween(bg_img, "y", Regular.easeOut, posit2, xDown2, 2, true);                
            trace(bg_img.y);
        

        if (isUpPressed)
        
            tweenUp = new Tween(bg_img, "y", Regular.easeOut, posit2, xUp2, 2, true);
            trace(bg_img.y);
        
    

更新：这成功了

var posit:Number = layers_mc.y;
var xDown:Number = Math.max(-618.5, layers_mc.y - 200, stage.stageHeight - layers_mc.height); 
var xUp:Number = Math.min(500, layers_mc.y + 200);

【参考方案1】：

听起来您想约束对象，使您无法将其滚动到可以看到其边缘的位置？

在这种情况下，您需要清理您的价值，使其不会超出这一点。

所以，为了向下移动对象，而不是像你在这里做的那样仅仅减去 200：

var xDown:Number = layers_mc.y - 200;

取较大的值，边缘可见之前的 -y 或当前值小于 200。

var xDown:Number = Math.max(layers_mc.y - 200, stage.stageHeight -layers_mc.height);

如果您取舞台高度（或任何可见边界），然后减去子对象的高度，这将为您提供最高点，您的对象仍然可以在舞台底部保持边缘。

因此，您需要确保所有值都遵循以下规则：（使用 if 语句或 Math.max/min 等）

允许的最小 y 点： stage.stageHeight - object.height;

允许的最大 y 点： 0

相反，如果您同时进行左右平移：

允许的最小 x 点： stage.stageWidth - object.width

允许的最大 x 点： 0

所以你的代码看起来像这样：

var xDown:Number = Math.max(layers_mc.y - 200, stage.stageWidth - layers_mc.height)); //make sure the value doesn't go less than stageWidth - layer height
var xUp:Number = Math.min(0, layers_mc.y + 200); //make sure the value doesn't go above 0