[英]globalAlpha on one image in canvas
I would like to do a little animation with html5-canvas. 我想用html5-canvas做一些动画。 I have background, mug on background, coins in this mug which is transparently. 我有背景,背景上有杯子,这个杯子里的硬币是透明的。 I want fade effect, when mug is appearing. 当杯子出现时,我想要褪色效果。 I have a problem, because when i give globalAlpha for mug, the rest got the same results. 我有一个问题,因为当我将globalAlpha用作杯子时,其余的结果相同。 I want animation, where i could give fade effect for each element. 我想要动画,我可以为每个元素赋予淡入淡出效果。 Now i have this: 现在我有这个:
<body>
<canvas id="myCanvas" width="1600" height="900"></canvas>
<script>
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
var background = new Image();
var money1 = new Image();
var money2 = new Image();
var money3 = new Image();
var money4 = new Image();
var money5 = new Image()
var mug = new Image();
var move = 0.01;
background.onload = function() {
context.drawImage(background, 0, 0);
}
mug.onload = function(){
context.globalAlpha = 0;
var i = 0;
var imgFadeInter = setInterval(function(){
context.globalAlpha += 0.01;
var a = context.drawImage(mug, 33, 212)
console.log(a, 'text');
i++;
if(i == 10){
clearInterval(imgFadeInter)
}
}, 10);
};
money1.onload = function() {
context.drawImage(money1, 155, 362);
};
money2.onload = function() {
context.drawImage(money2, 158, 360);
};
money3.onload = function() {
context.drawImage(money3, 151, 358);
};
money4.onload = function() {
context.drawImage(money4, 148, 301);
};
money5.onload = function() {
context.drawImage(money5, 136, 265);
};
background.src = 'background-mag.png';
setTimeout(function(){mug.src = 'mug.png'}, 500);
setTimeout(function(){money1.src = 'money1.png'}, 1000);
setTimeout(function(){money2.src = 'money2.png'}, 2000);
setTimeout(function(){money3.src = 'money3.png'}, 3000);
setTimeout(function(){money4.src = 'money4.png'}, 4000);
setTimeout(function(){money5.src = 'money5.png'}, 5000);
</script>
Sorry for my english, I hope it what i wrote is understandable.. 对不起我的英语,我希望我写的是可以理解的。
You can add custom properties to your image objects, so add the alpha you desire for each image: 您可以向图像对象添加自定义属性,因此为每个图像添加所需的Alpha:
// start with money1's alpha at a low alpha so you can fade it in
// alpha will be divided by 100 later (using ints prevents rounding problems)
money1.alpha=20;
Then when you drawImage
in your animation loop you can set individual globalAlpha
based on the added property: 然后,当您在动画循环中drawImage
,您可以根据添加的属性设置各个globalAlpha
:
if(money1.alpha<=100){
// draw money1 at its current alpha
context.globalAlpha=money1.alpha/100;
context.drawImage(money1, 155, 362);
// be sure to tidy up...reset globalAlpha to its default of 1.00
context.globalAlpha=1.00;
// increase the alpha
money1.alpha+=1;
};
Good luck with your project! 祝您项目顺利!
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.