vue3 粒子动画 canvas

<template>

  <div class="">

    <canvas id="canvas"></canvas>

  </div>

</template>

<script setup>

import { onMounted } from 'vue';

let d

const 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 };

  }

}

const 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;

}

const 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);

}

const 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]];

}

const 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];

}

const 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);

}

const process = (vars) =>{

  if(vars.points.length<vars.initParticles) for(var i=0;i<5;++i) spawnParticle(vars);

  var p,d,t, x, y, z;

  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);

    }

  }

}

const drawFloor = (vars) => {

  var x = ''

  let y = ''

  let z = ''

  let d = ''

  let point = ''

  let a =''

  let size

  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);

        }

      }

    }

  }

}

const sortFunction = (a,b) => {

  return b.dist-a.dist;

}

const 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, size;

  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);

}

const spawnParticle = (vars) => {

  var p,ls;

  let 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);

}

const 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);

}

onMounted(() => {

  console.log('sss')

  frame()

})

</script>

<style scoped lang="scss">

canvas {

   overflow: hidden;

   width:100%;

   height:1000px;

   background-color:black;

}

</style>