Javascript画布动画
我正在使用javascript和画布创建动画。如何允许用户指定帧的显示顺序并更改帧的显示速度。这就是我目前所拥有的Javascript画布动画,javascript,animation,canvas,Javascript,Animation,Canvas,我正在使用javascript和画布创建动画。如何允许用户指定帧的显示顺序并更改帧的显示速度。这就是我目前所拥有的 (function() { var lastTime = 0; var vendors = ['ms', 'moz', 'webkit', 'o']; for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) { window.requestAnimationFr
(function() {
var lastTime = 0;
var vendors = ['ms', 'moz', 'webkit', 'o'];
for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) {
window.requestAnimationFrame = window[vendors[x]+'RequestAnimationFrame'];
window.cancelAnimationFrame = window[vendors[x]+'CancelAnimationFrame']
|| window[vendors[x]+'CancelRequestAnimationFrame'];
}
if (!window.requestAnimationFrame)
window.requestAnimationFrame = function(callback, element) {
var currTime = new Date().getTime();
var timeToCall = Math.max(0, 16 - (currTime - lastTime));
var id = window.setTimeout(function() { callback(currTime + timeToCall); },
timeToCall);
lastTime = currTime + timeToCall;
return id;
};
if (!window.cancelAnimationFrame)
window.cancelAnimationFrame = function(id) {
clearTimeout(id);
};
}());
(function () {
var coin,
coinImage,
canvas;
function gameLoop () {
window.requestAnimationFrame(gameLoop);
coin.update();
coin.render();
}
function sprite (options) {
var that = {},
frameIndex = 0,
tickCount = 0,
ticksPerFrame = options.ticksPerFrame || 0,
numberOfFrames = options.numberOfFrames || 1;
that.context = options.context;
that.width = options.width;
that.height = options.height;
that.image = options.image;
that.update = function () {
tickCount += 1;
if (tickCount > ticksPerFrame) {
tickCount = 0;
// If the current frame index is in range
if (frameIndex < numberOfFrames - 1) {
// Go to the next frame
frameIndex += 1;
} else {
frameIndex = 0;
}
}
};
that.render = function () {
// Clear the canvas
that.context.clearRect(0, 0, that.width, that.height);
// Draw the animation
that.context.drawImage(
that.image,
frameIndex * that.width / numberOfFrames,
0,
that.width / numberOfFrames,
that.height,
0,
0,
that.width / numberOfFrames,
that.height);
};
return that;
}
// Get canvas
canvas = document.getElementById("coinAnimation");
canvas.width = 500;
canvas.height = 500;
// Create sprite sheet
coinImage = new Image();
// Create sprite
coin = sprite({
context: canvas.getContext("2d"),
width: 500,
height:72,
image: coinImage,
numberOfFrames: 10,
ticksPerFrame: 4
});
// Load sprite sheet
coinImage.addEventListener("load", gameLoop);
coinImage.src = "sprite.png";
} ());
(函数(){
var lastTime=0;
var供应商=['ms','moz','webkit','o'];
对于(var x=0;x滴答声帧){
滴答数=0;
//如果当前帧索引在范围内
如果(frameIndex
Rq:您可能会删除为不支持它的浏览器定义requestAnimationFrame的代码,因为1)setTimeout太不准确,2)支持画布的浏览器很可能无法实现它,因此polyfill就足够了
要更改硬币动画,您需要使用时间参数(dt,自上一帧以来经过的时间)进行精灵更新。因此,计算更新循环中的时间:让它计算游戏时间和当前帧的dt(你为rAF所做的可以在这里重用)
然后,您需要某种方法在您的精灵中存储帧/帧持续时间数据
您可以使用{duration:,frame:}对象数组。我个人喜欢这样的数组:[duration1,frameIndex1,duration2,frameIndex2,…](如果使用切片(0)复制它,速度更快,并且没有引用问题) 然后在硬币的更新过程中,你必须处理当前的时间位置,而不是滴答数,并且用你手头的dt“吃掉”尽可能多的持续时间,以找到下一帧 现在来回答你的问题,为了编辑动画,我将在你的显示画布下面使用一个单独的画布,和一组按钮来改变事情。 我做了一个非常简单的jsbin,它看起来像这样: jsbin在这里: