Canvas：樱花树之恋

来源：互联网发布：linux中启动tomcat 编辑：程序博客网时间：2024/04/27 19:31

一、代码

<!doctype html><html><head><meta http-equiv="Pragma" content="no-cache" /><meta http-equiv="Cache-Control" content="no-cache" /><meta http-equiv="Expires" content="0" /><meta http-equiv="Content-Type" content="text/html;charset=utf-8" /><meta name="viewport" content="width=device-width,initial-scale=1.0,user-scalable=no" /><style type="text/css">canvas{    position: absolute;    left: 0;    top: 0;}</style></head><body bgcolor="#000000"><canvas id="tree"></canvas><canvas id="flower"></canvas><script>//两个canvasvar tree = document.getElementById("tree");tree.width = window.innerWidth;tree.height = window.innerHeight ;var tCxt = tree.getContext("2d");var flower = document.getElementById("flower");flower.width = window.innerWidth;flower.height = window.innerHeight ;var cxt = flower.getContext("2d");var flowerList = [];//樱花列表var rootTop = 450 ;//树起点var flowerColor = "rgba(255,192,203,.3)" ;//花色var flowerColorDeep = "rgba(241,158,194,.5)" ;//花色深var treeColor2 = "rgba(255,192,203,.5)" ;//树枝颜色var treeColor = "#FFF" ;//树干颜色var fallList = [];//飘落樱花列表var g = 0.01 ;//重力加速度var gWind = 0.005;//风力加速度var limitSpeedY = 1;//速度上限var limitSpeedX = 1 ;//速度上限cxt.shadowColor= "#FFF" ;cxt.shadowBlur = 10 ;function drawTree(x,y,deg,step,type){    var deg1 = step%2 == 0 ? 0.1 : -0.1 ;    var x1 = x + Math.cos(deg+deg1) * (step+4) * 0.8 ;//以步长来判断枝干长度 x轴偏移大一些    var y1 = y + Math.sin(deg+deg1) * (step-1) * 0.8 ;//以步长来判断枝干长度 Y轴压缩一些    tCxt.beginPath();    tCxt.lineWidth = step/3;    tCxt.moveTo(x,y);    tCxt.lineTo(x1,y1);    tCxt.strokeStyle = (step > 5 ) ? treeColor : treeColor2 ;//细纸条都换成花的颜色    tCxt.stroke();    if(step > 20){//树干相交的位置有间隙，以一个圆填充        tCxt.fillStyle = treeColor ;        tCxt.arc(x,y,step/6,0,Math.PI*2);        tCxt.fill();    }    if(step < 3 || (step < 23 && Math.random() > 0.1)){        //末梢位置 画花瓣        var color = [flowerColorDeep,flowerColor,flowerColor][Math.round(Math.random()+0.2)] ;        var r = 2+Math.random()*2        tCxt.fillStyle = color ;        tCxt.arc(x1+Math.random()*3,y1+Math.random()*3,r,0,Math.PI)        tCxt.fill();        flowerList.push({x:x,y:y,sx:(Math.random()-0.5),sy:0,color:color,r:r,deg:deg});//保存下画樱花的位置    }    step -- ;    if(step > 0){        drawTree(x1,y1,deg,step,type);        if(step%3 == 1 && step > 0 && step < 30)            drawTree(x1,y1,deg+0.2 + 0.3 * Math.random(),Math.round(step/1.13));//右分叉        if(step%3 == 0 && step > 0 && step < 30)            drawTree(x1,y1,deg-0.2 - 0.3 * Math.random(),Math.round(step/1.13));//左分叉    }}drawTree(tree.width/2,rootTop,-Math.PI/2,30,1);//执行var len = flowerList.length ;function step(){    if(Math.random() > 0.3)    fallList.push(flowerList[Math.floor(Math.random()*len)]);//随机取出一个，花瓣复制到飘落花瓣的列表中    cxt.clearRect(0,0,tree.width,tree.height);    for(var i = 0 ;i < fallList.length ; i ++){        if(fallList[i].sy < limitSpeedY) fallList[i].sy += g ;        fallList[i].sx += gWind ;        fallList[i].x += fallList[i].sx ;        fallList[i].y += fallList[i].sy ;        if(fallList[i].y > rootTop){//飘到树根的花瓣移除            fallList.splice(i,1);            i -- ;            continue ;        }        cxt.beginPath();        cxt.fillStyle = fallList[i].color ;        fallList[i].deg += fallList[i].sx*0.05 ;//跟速度相关的旋转花瓣        cxt.arc(fallList[i].x,fallList[i].y,fallList[i].r,fallList[i].deg,fallList[i].deg+Math.PI*1.3);        cxt.fill();    }    requestAnimationFrame(step);}requestAnimationFrame(step);</script></body></html>

效果演示

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文章系转载，更多详情见：樱花的季节，教大家用canvas画出飞舞的樱花树

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