问题描述
我正在寻找一种简单的方法，它可以让我在画布上绘制 paint splash 像这样:
I'm looking for a simple method which can able me to draw in a canvas a paint splash like this on :
一种方法是发射很多小粒子，这会画一个小圆圈，但我不想管理很多粒子对象.
One method will be to fire a lot of small particles which will paint a little circle, but I don't want to manage a lot of particle objects.
编辑:示例: jsfiddle.net/MK73j/4/
第二种方法是使用少量图像并控制缩放和旋转，但我希望效果具有良好的随机性.
A second method will be to have few images and manipulate scale and rotation, but I want to have a good random on the effect.
第三种方法是制作一些随机的小点，用贝塞尔曲线连接它们并填充内容，但我只有一个标记.
A third method will be to make some random litte points, join them with bezier curves and fill the content, but I will have only a single mark.
嗯，我不知道是否有更好的方法来产生看起来像这张图片的效果，或者我是否必须从我想到的 3 个中进行选择.
Well I don't know if there is a better method to have an effect which looks like this image or if I have to choose on of the 3 I thought about.
推荐答案
您可以使用错觉来创建漂亮的 splat 效果.
You can use illusion to create a nice splat effect.
由于对象在接近时会增长"，因此您可以通过动画增加尺寸加上一点动作来创建喷溅效果.
Since objects "grow" as they approach, you can animate an increasing size plus a little motion to create your splat effect.
您可以使用 context.drawImage 来处理大小调整:
You can use context.drawImage to handle the resizing:
context.drawImage(splashImg, 0 ,0, splashImg.width, splashImg.height,
newX, newY, newWidth, newHeight);
这是代码和小提琴:http://jsfiddle.net/m1erickson/r8Grf/
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<style>
body{ background-color: ivory; }
canvas{border:1px solid red;}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
window.requestAnimFrame = (function(callback) {
return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame ||
function(callback) {
window.setTimeout(callback, 1000 / 60);
};
})();
$("go").html("Loading...");
var count=80;
var win=new Image();
var splash;
win.onload=function(){
splash=new Image();
splash.onload=function(){
ctx.drawImage(win,0,0);
}
splash.src="http://dl.dropbox.com/u/139992952/splash2.svg";
}
win.src="http://dl.dropbox.com/u/139992952/window.png";
$("#go").click(function(){ count=80; animate(); });
function animate() {
// drawings
if(--count>1){
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.save();
ctx.drawImage(win,0,0);
ctx.globalCompositeOperation = 'destination-over';
ctx.drawImage(splash,0,0,splash.width,splash.height,25,25,splash.width/count,splash.height/count);
ctx.restore();
}
// request new frame
requestAnimFrame(function() {
animate();
});
}
}); // end $(function(){});
</script>
</head>
<body>
<br/><button id="go">Splash!</button><br/><br/>
<canvas id="canvas" width=326 height=237></canvas>
</body>
</html>
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