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I have always wanted to write a rain effect, but both in terms of time and myself, I instinctively avoid it and don’t have much courage to face it head-on. Even this effect is not difficult to achieve. . It seems that in the process of cultivation, further strengthening is needed. Because it is a very simple method and there are only a few lines of code, the idea is implemented. The main code is mainly the canvas non-stop random Draw to form the visual effect of continuous rain:
(function(){ var canvas = document.getElementById_x('canvas'); var ctx = canvas.getContext('2d'); var w = document.documentElement.offsetWidth; var h = document.documentElement.offsetHeight; var x = 0, y = 0,len = 200,angle = -2,count = 100; var rainTimer = null,drawTimer = null; //线条颜色 var color = ctx.createLinearGradient(0,0,0,len); color.addColorStop(0,'purple'); color.addColorStop(1,'rgba(255,255,255,0.2)'); //ctx.strokeStyle = 'rgba(255,255,255,0.2)'; ctx.strokeStyle = color; function drawRain(x,y) { //每次绘制渐变线条 都需要找到坐标 var color = ctx.createLinearGradient(x,y,x+angle,y+len); //color.addColorStop(0,'rgba(254,139,199,0.3)'); color.addColorStop(0,'rgba(0,0,0,0.1'); color.addColorStop(1,'rgba(255,255,255,0.2)'); ctx.strokeStyle = color; ctx.beginPath() ctx.moveTo(x,y); ctx.lineWidth=1; ctx.lineTo(x + angle,y+len); ctx.stroke(); } //绘制满屏的雨滴 function fullWindowRain() { var i = 0; for(i = 0;i < count; i++) { drawRain(w*Math.random(),h*Math.random()); } } //改变大雨或者小雨 function changeRain() { rainTimer = setInterval(function(){ count = Math.ceil(500 + 100 * Math.random()); },2000); } changeRain(); reDraw(); //重绘的频率 function reDraw() { drawTimer = setInterval(function(){ ctx.clearRect(0,0,w,h+200); fullWindowRain(); },100); } })();
Note: It should be noted that each time you draw, you need to create a gradient color again, because creating a gradient color requires coordinate values.
Of course, under normal circumstances, you need to create several variables to control the raindrops Raindrop angle, raindrop length, raindrop number, etc.
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