预加载图像后使用EaselJS翻转SpriteSheet动画

时间:2013-06-13 12:06:41

标签: easeljs

我正试图从SpriteSheet动画中水平翻转精灵。我从this example

开始

我在创建 SpriteSheet 后立即添加了翻转的框架

    var ss = new createjs.SpriteSheet(spriteSheet);

    createjs.SpriteSheetUtils.addFlippedFrames(ss, true, false, false);

    grant = new createjs.BitmapAnimation(ss);
...

我总是得到这个错误:

Uncaught TypeError: Cannot read property 'length' of null    (SpriteSheetUtils.js l.174)

我看到有人在此github thread遇到同样的问题 并使用preload mecanism修复它。

该示例也使用预加载,所以我试图在资源加载后调用addFlippedFrames,但我仍然看到相同的错误。

有没有人能为我提供线索? 我该如何使用addFlippedFrames?

编辑: 这是我试过的代码:

使用我的spritesheet初始化舞台:

    spriteSheet = new createjs.SpriteSheet({
        "animations": {
            "none": [0, 0],
            "run": [0, 25],
            "jump": [26, 63]
        },
        "images": ["characters/grant/runningGrant.png"],
        "frames": {
            "height": h,
            "width": w,
            "regX": 0,
            "regY": 0,
            "count": 64
        }
    });



    sprite = new createjs.BitmapAnimation(spriteSheet);
    sprite.x = startPosition.x;
    sprite.y = startPosition.y;

// Add the sprite to the stage.
stage.addChild(this.sprite);

然后像这样使用预载:

var manifest = [{
        src: "characters/grant/runningGrant.png",
        id: "grant"
    }
];

var loader = new createjs.LoadQueue(false);
loader.onFileLoad = handleFileLoad;
loader.onComplete = onResourcesLoaded;
loader.loadManifest(manifest);

和回调函数:

handleFileLoad = function(event) {
    assets.push(event.item);
};

onResourcesLoaded = function() {

    for (var i = 0; i < assets.length; i++) {
        var item = assets[i];
        var id = item.id;
        var result = loader.getResult(id);

        if (item.type == createjs.LoadQueue.IMAGE) {
            var bmp = new createjs.Bitmap(result);
                //does this Bitmap creation trigger the real bitmap loading ?
                //is this loading asynchrous which would explain my problem.
                //in this case, how can I manage the loading callback ?
        }
    }

    //I would expect here to have the image fully loaded but its not
    //A timeout of 2 seconds makes the addFlippedFrames works.
    setTimeout(function(){
            createjs.SpriteSheetUtils.addFlippedFrames(spriteSheet, true, false, false);
            sprite.gotoAndPlay("run_h"); //I think "run_h" is used to launch the flipped version of "run"
    }, 2000);
};

2 个答案:

答案 0 :(得分:3)

你的问题是,你创建了一个带有image-url的SpriteSheet,这已经触发了一个加载过程,preload-js队列实际上没有加载任何东西,因为图像的加载已经在进行中,所以“onComplete” “-event在图像实际加载之前总是被触发 - 这是有道理的,因为不需要加载图像两次

我已经更新了你的jsfiddle并添加了一些评论:http://jsfiddle.net/K4TmS/1/(完整代码)

spriteSheet = new createjs.SpriteSheet({
            "animations": {
                "none": [0, 0],
                "run": [0, 25],
                "jump": [26, 63]
            },
            //this line in YOUR version triggered an own loading process, independent from the queue
            "images": [result],  
            "frames": {
                "height": 292.5,
                "width":165.75,
                "regX": 0,
                "regY": 0,
                "count": 64
            }
        });

// this was executed instantly, because the image was already in another loading progress, and therefore wasn't even added to the queue
loader.onComplete = onResourcesLoaded;

这里的参数可以忽略DOM安全错误18(用于开发)Disable same origin policy in Chrome 但是对于生产,您应该只从同一台服务器加载img,然后图像操作不会出错。

所以简而言之:你的问题是由于执行错误的顺序,请记住:如果你使用预加载:在其他所有事情之前预先加载,并且没有其他事情直到预加载没有完成。 (除了加载图形/动画/指示器)。

答案 1 :(得分:2)

使用scaleX很容易

if(right == true)
    {
        //walking direction en sprite switch
        rogerWalk.scaleX = -1 * rogerWalk.scaleX;
        right = false;
    }

//我曾经做过的代码(在这种情况下,roger向右走(标准精灵方向)

if(right == false)
    {
        rogerWalk.scaleX = -1 * rogerWalk.scaleX;
        right = true;

//这是我有的keyleft / keyright功能

我知道这篇文章很老但是仍有人可以使用它:)