240行代码实现粒子漩涡特效
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240行代码实现粒子漩涡特效

青帝
2022-12-06 / 1 评论 / 184 阅读 / 正在检测是否收录...

源代码

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>iarc.top/x</title>
<style>
html,body{
    margin:0px;
    width:100%;
    height:100%;
    overflow:hidden;
  background:#000;
}
#canvas{
    position:absolute;
    width:100%;
    height:100%;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script>
function project3D(x,y,z,vars){
    var p,d;
    x-=vars.camX;
    y-=vars.camY-8;
    z-=vars.camZ;
    p=Math.atan2(x,z);
    d=Math.sqrt(x*x+z*z);
    x=Math.sin(p-vars.yaw)*d;
    z=Math.cos(p-vars.yaw)*d;
    p=Math.atan2(y,z);
    d=Math.sqrt(y*y+z*z);
    y=Math.sin(p-vars.pitch)*d;
    z=Math.cos(p-vars.pitch)*d;
    var rx1=-1000;
    var ry1=1;
    var rx2=1000;
    var ry2=1;
    var rx3=0;
    var ry3=0;
    var rx4=x;
    var ry4=z;
    var uc=(ry4-ry3)*(rx2-rx1)-(rx4-rx3)*(ry2-ry1);
    var ua=((rx4-rx3)*(ry1-ry3)-(ry4-ry3)*(rx1-rx3))/uc;
    var ub=((rx2-rx1)*(ry1-ry3)-(ry2-ry1)*(rx1-rx3))/uc;
    if(!z)z=0.000000001;
    if(ua>0&&ua<1&&ub>0&&ub<1){
        return {
            x:vars.cx+(rx1+ua*(rx2-rx1))*vars.scale,
            y:vars.cy+y/z*vars.scale,
            d:(x*x+y*y+z*z)
        };
    }else{
        return { d:-1 };
    }
}
function elevation(x,y,z){
    var dist = Math.sqrt(x*x+y*y+z*z);
    if(dist && z/dist>=-1 && z/dist <=1) return Math.acos(z / dist);
    return 0.00000001;
}
function rgb(col){
    col += 0.000001;
    var r = parseInt((0.5+Math.sin(col)*0.5)*16);
    var g = parseInt((0.5+Math.cos(col)*0.5)*16);
    var b = parseInt((0.5-Math.sin(col)*0.5)*16);
    return "#"+r.toString(16)+g.toString(16)+b.toString(16);
}
function interpolateColors(RGB1,RGB2,degree){
    var w2=degree;
    var w1=1-w2;
    return [w1*RGB1[0]+w2*RGB2[0],w1*RGB1[1]+w2*RGB2[1],w1*RGB1[2]+w2*RGB2[2]];
}
function rgbArray(col){
    col += 0.000001;
    var r = parseInt((0.5+Math.sin(col)*0.5)*256);
    var g = parseInt((0.5+Math.cos(col)*0.5)*256);
    var b = parseInt((0.5-Math.sin(col)*0.5)*256);
    return [r, g, b];
}
function colorString(arr){
    var r = parseInt(arr[0]);
    var g = parseInt(arr[1]);
    var b = parseInt(arr[2]);
    return "#"+("0" + r.toString(16) ).slice (-2)+("0" + g.toString(16) ).slice (-2)+("0" + b.toString(16) ).slice (-2);
}
function process(vars){
    if(vars.points.length<vars.initParticles) for(var i=0;i<5;++i) spawnParticle(vars);
    var p,d,t;    
    p = Math.atan2(vars.camX, vars.camZ);
    d = Math.sqrt(vars.camX * vars.camX + vars.camZ * vars.camZ);
    d -= Math.sin(vars.frameNo / 80) / 25;
    t = Math.cos(vars.frameNo / 300) / 165;
    vars.camX = Math.sin(p + t) * d;
    vars.camZ = Math.cos(p + t) * d;
    vars.camY = -Math.sin(vars.frameNo / 220) * 15;
    vars.yaw = Math.PI + p + t;
    vars.pitch = elevation(vars.camX, vars.camZ, vars.camY) - Math.PI / 2;    
    var t;
    for(var i=0;i<vars.points.length;++i){        
        x=vars.points[i].x;
        y=vars.points[i].y;
        z=vars.points[i].z;
        d=Math.sqrt(x*x+z*z)/1.0075;
        t=.1/(1+d*d/5);
        p=Math.atan2(x,z)+t;
        vars.points[i].x=Math.sin(p)*d;
        vars.points[i].z=Math.cos(p)*d;
        vars.points[i].y+=vars.points[i].vy*t*((Math.sqrt(vars.distributionRadius)-d)*2);
        if(vars.points[i].y>vars.vortexHeight/2 || d<.25){
            vars.points.splice(i,1);
            spawnParticle(vars);
        }
    }
}
function drawFloor(vars){    
    var x,y,z,d,point,a;
    for (var i = -25; i <= 25; i += 1) {
        for (var j = -25; j <= 25; j += 1) {
            x = i*2;
            z = j*2;
            y = vars.floor;
            d = Math.sqrt(x * x + z * z);
            point = project3D(x, y-d*d/85, z, vars);
            if (point.d != -1) {
                size = 1 + 15000 / (1 + point.d);
                a = 0.15 - Math.pow(d / 50, 4) * 0.15;
                if (a > 0) {
                    vars.ctx.fillStyle = colorString(interpolateColors(rgbArray(d/26-vars.frameNo/40),[0,128,32],.5+Math.sin(d/6-vars.frameNo/8)/2));
                    vars.ctx.globalAlpha = a;
                    vars.ctx.fillRect(point.x-size/2,point.y-size/2,size,size);
                }
            }
        }
    }        
    vars.ctx.fillStyle = "#82f";
    for (var i = -25; i <= 25; i += 1) {
        for (var j = -25; j <= 25; j += 1) {
            x = i*2;
            z = j*2;
            y = -vars.floor;
            d = Math.sqrt(x * x + z * z);
            point = project3D(x, y+d*d/85, z, vars);
            if (point.d != -1) {
                size = 1 + 15000 / (1 + point.d);
                a = 0.15 - Math.pow(d / 50, 4) * 0.15;
                if (a > 0) {
                    vars.ctx.fillStyle = colorString(interpolateColors(rgbArray(-d/26-vars.frameNo/40),[32,0,128],.5+Math.sin(-d/6-vars.frameNo/8)/2));
                    vars.ctx.globalAlpha = a;
                    vars.ctx.fillRect(point.x-size/2,point.y-size/2,size,size);
                }
            }
        }
    }        
}
function sortFunction(a,b){
    return b.dist-a.dist;
}
function draw(vars){
    vars.ctx.globalAlpha=.15;
    vars.ctx.fillStyle="#000";
    vars.ctx.fillRect(0, 0, canvas.width, canvas.height);
    drawFloor(vars);    
    var point,x,y,z,a;
    for(var i=0;i<vars.points.length;++i){
        x=vars.points[i].x;
        y=vars.points[i].y;
        z=vars.points[i].z;
        point=project3D(x,y,z,vars);
        if(point.d != -1){
            vars.points[i].dist=point.d;
            size=1+vars.points[i].radius/(1+point.d);
            d=Math.abs(vars.points[i].y);
            a = .8 - Math.pow(d / (vars.vortexHeight/2), 1000) * .8;
            vars.ctx.globalAlpha=a>=0&&a<=1?a:0;
            vars.ctx.fillStyle=rgb(vars.points[i].color);
            if(point.x>-1&&point.x<vars.canvas.width&&point.y>-1&&point.y<vars.canvas.height)vars.ctx.fillRect(point.x-size/2,point.y-size/2,size,size);
        }
    }
    vars.points.sort(sortFunction);
}
function spawnParticle(vars){

    var p,ls;
    pt={};
    p=Math.PI*2*Math.random();
    ls=Math.sqrt(Math.random()*vars.distributionRadius);
    pt.x=Math.sin(p)*ls;
    pt.y=-vars.vortexHeight/2;
    pt.vy=vars.initV/20+Math.random()*vars.initV;
    pt.z=Math.cos(p)*ls;
    pt.radius=200+800*Math.random();
    pt.color=pt.radius/1000+vars.frameNo/250;
    vars.points.push(pt);    
}
function frame(vars) {
    if(vars === undefined){
        var vars={};
        vars.canvas = document.querySelector("canvas");
        vars.ctx = vars.canvas.getContext("2d");
        vars.canvas.width = document.body.clientWidth;
        vars.canvas.height = document.body.clientHeight;
        window.addEventListener("resize", function(){
            vars.canvas.width = document.body.clientWidth;
            vars.canvas.height = document.body.clientHeight;
            vars.cx=vars.canvas.width/2;
            vars.cy=vars.canvas.height/2;
        }, true);
        vars.frameNo=0;

        vars.camX = 0;
        vars.camY = 0;
        vars.camZ = -14;
        vars.pitch = elevation(vars.camX, vars.camZ, vars.camY) - Math.PI / 2;
        vars.yaw = 0;
        vars.cx=vars.canvas.width/2;
        vars.cy=vars.canvas.height/2;
        vars.bounding=10;
        vars.scale=500;
        vars.floor=26.5;

        vars.points=[];
        vars.initParticles=700;
        vars.initV=.01;
        vars.distributionRadius=800;
        vars.vortexHeight=25;
    }
    vars.frameNo++;
    requestAnimationFrame(function() {
        frame(vars);
    });
    process(vars);
    draw(vars);
}
frame();
</script>
</body>
</html>

演示站点:https://iarc.top/x

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