JS如何实现实现超好看的3D烟花特效？（代码示例）

互联网 20-6-12
废话不多说，直接上代码：
<!doctype html> <html> <head> <meta charset="utf-8"> <title>3D烟花</title>   <style> html,body{  margin:0px;  width:100%;  height:100%;  overflow:hidden;  background:#000; }   #canvas{  width:100%;  height:100%; } </style> </head> <body> <canvas id="canvas"></canvas><script> function initVars(){    pi=Math.PI;  ctx=canvas.getContext("2d");  canvas.width=canvas.clientWidth;  canvas.height=canvas.clientHeight;  cx=canvas.width/2;  cy=canvas.height/2;  playerZ=-25;  playerX=playerY=playerVX=playerVY=playerVZ=pitch=yaw=pitchV=yawV=0;  scale=600;  seedTimer=0;seedInterval=5,seedLife=100;gravity=.02;  seeds=new Array();  sparkPics=new Array();  s="https://cantelope.org/NYE/";  for(i=1;i<=10;++i){  sparkPic=new Image();  sparkPic.src=s+"spark"+i+".png";  sparkPics.push(sparkPic);  }  sparks=new Array();  pow1=new Audio(s+"pow1.ogg");  pow2=new Audio(s+"pow2.ogg");  pow3=new Audio(s+"pow3.ogg");  pow4=new Audio(s+"pow4.ogg");  frames = 0; }   function rasterizePoint(x,y,z){    var p,d;  x-=playerX;  y-=playerY;  z-=playerZ;  p=Math.atan2(x,z);  d=Math.sqrt(x*x+z*z);  x=Math.sin(p-yaw)*d;  z=Math.cos(p-yaw)*d;  p=Math.atan2(y,z);  d=Math.sqrt(y*y+z*z);  y=Math.sin(p-pitch)*d;  z=Math.cos(p-pitch)*d;  var rx1=-1000,ry1=1,rx2=1000,ry2=1,rx3=0,ry3=0,rx4=x,ry4=z,uc=(ry4-ry3)*(rx2-rx1)-(rx4-rx3)*(ry2-ry1);  if(!uc) return {x:0,y:0,d:-1};  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=.000000001;  if(ua>0&&ua<1&&ub>0&&ub<1){  return {   x:cx+(rx1+ua*(rx2-rx1))*scale,   y:cy+y/z*scale,   d:Math.sqrt(x*x+y*y+z*z)  };  }else{  return {   x:cx+(rx1+ua*(rx2-rx1))*scale,   y:cy+y/z*scale,   d:-1  };  } }   function spawnSeed(){     seed=new Object();  seed.x=-50+Math.random()*100;  seed.y=25;  seed.z=-50+Math.random()*100;  seed.vx=.1-Math.random()*.2;  seed.vy=-1.5;//*(1+Math.random()/2);  seed.vz=.1-Math.random()*.2;  seed.born=frames;  seeds.push(seed); }   function splode(x,y,z){     t=5+parseInt(Math.random()*150);  sparkV=1+Math.random()*2.5;  type=parseInt(Math.random()*3);  switch(type){  case 0:   pic1=parseInt(Math.random()*10);   break;  case 1:   pic1=parseInt(Math.random()*10);   do{ pic2=parseInt(Math.random()*10); }while(pic2==pic1);   break;  case 2:   pic1=parseInt(Math.random()*10);   do{ pic2=parseInt(Math.random()*10); }while(pic2==pic1);   do{ pic3=parseInt(Math.random()*10); }while(pic3==pic1 || pic3==pic2);   break;  }  for(m=1;m<t;++m){  spark=new Object();  spark.x=x; spark.y=y; spark.z=z;  p1=pi*2*Math.random();  p2=pi*Math.random();  v=sparkV*(1+Math.random()/6)  spark.vx=Math.sin(p1)*Math.sin(p2)*v;  spark.vz=Math.cos(p1)*Math.sin(p2)*v;  spark.vy=Math.cos(p2)*v;  switch(type){   case 0: spark.img=sparkPics[pic1]; break;   case 1:   spark.img=sparkPics[parseInt(Math.random()*2)?pic1:pic2];   break;   case 2:   switch(parseInt(Math.random()*3)){    case 0: spark.img=sparkPics[pic1]; break;    case 1: spark.img=sparkPics[pic2]; break;    case 2: spark.img=sparkPics[pic3]; break;   }   break;  }  spark.radius=25+Math.random()*50;  spark.alpha=1;  spark.trail=new Array();  sparks.push(spark);  }  switch(parseInt(Math.random()*4)){  case 0: pow=new Audio(s+"pow1.ogg"); break;  case 1: pow=new Audio(s+"pow2.ogg"); break;  case 2: pow=new Audio(s+"pow3.ogg"); break;  case 3: pow=new Audio(s+"pow4.ogg"); break;  }  d=Math.sqrt((x-playerX)*(x-playerX)+(y-playerY)*(y-playerY)+(z-playerZ)*(z-playerZ));  pow.volume=1.5/(1+d/10);  pow.play(); }   function doLogic(){     if(seedTimer<frames){  seedTimer=frames+seedInterval*Math.random()*10;  spawnSeed();  }  for(i=0;i<seeds.length;++i){  seeds[i].vy+=gravity;  seeds[i].x+=seeds[i].vx;  seeds[i].y+=seeds[i].vy;  seeds[i].z+=seeds[i].vz;  if(frames-seeds[i].born>seedLife){   splode(seeds[i].x,seeds[i].y,seeds[i].z);   seeds.splice(i,1);  }  }  for(i=0;i<sparks.length;++i){  if(sparks[i].alpha>0 && sparks[i].radius>5){   sparks[i].alpha-=.01;   sparks[i].radius/=1.02;   sparks[i].vy+=gravity;   point=new Object();   point.x=sparks[i].x;   point.y=sparks[i].y;   point.z=sparks[i].z;   if(sparks[i].trail.length){   x=sparks[i].trail[sparks[i].trail.length-1].x;   y=sparks[i].trail[sparks[i].trail.length-1].y;   z=sparks[i].trail[sparks[i].trail.length-1].z;   d=((point.x-x)*(point.x-x)+(point.y-y)*(point.y-y)+(point.z-z)*(point.z-z));   if(d>9){    sparks[i].trail.push(point);   }   }else{   sparks[i].trail.push(point);   }   if(sparks[i].trail.length>5)sparks[i].trail.splice(0,1);     sparks[i].x+=sparks[i].vx;   sparks[i].y+=sparks[i].vy;   sparks[i].z+=sparks[i].vz;   sparks[i].vx/=1.075;   sparks[i].vy/=1.075;   sparks[i].vz/=1.075;  }else{   sparks.splice(i,1);  }  }  p=Math.atan2(playerX,playerZ);  d=Math.sqrt(playerX*playerX+playerZ*playerZ);  d+=Math.sin(frames/80)/1.25;  t=Math.sin(frames/200)/40;  playerX=Math.sin(p+t)*d;  playerZ=Math.cos(p+t)*d;  yaw=pi+p+t; }   function rgb(col){     var r = parseInt((.5+Math.sin(col)*.5)*16);  var g = parseInt((.5+Math.cos(col)*.5)*16);  var b = parseInt((.5-Math.sin(col)*.5)*16);  return "#"+r.toString(16)+g.toString(16)+b.toString(16); }   function draw(){     ctx.clearRect(0,0,cx*2,cy*2);     ctx.fillStyle="#ff8";  for(i=-100;i<100;i+=3){  for(j=-100;j<100;j+=4){   x=i;z=j;y=25;   point=rasterizePoint(x,y,z);   if(point.d!=-1){   size=250/(1+point.d);   d = Math.sqrt(x * x + z * z);   a = 0.75 - Math.pow(d / 100, 6) * 0.75;   if(a>0){    ctx.globalAlpha = a;    ctx.fillRect(point.x-size/2,point.y-size/2,size,size);     }   }  }  }  ctx.globalAlpha=1;  for(i=0;i<seeds.length;++i){  point=rasterizePoint(seeds[i].x,seeds[i].y,seeds[i].z);  if(point.d!=-1){   size=200/(1+point.d);   ctx.fillRect(point.x-size/2,point.y-size/2,size,size);  }  }  point1=new Object();  for(i=0;i<sparks.length;++i){  point=rasterizePoint(sparks[i].x,sparks[i].y,sparks[i].z);  if(point.d!=-1){   size=sparks[i].radius*200/(1+point.d);   if(sparks[i].alpha<0)sparks[i].alpha=0;   if(sparks[i].trail.length){   point1.x=point.x;   point1.y=point.y;   switch(sparks[i].img){    case sparkPics[0]:ctx.strokeStyle="#f84";break;    case sparkPics[1]:ctx.strokeStyle="#84f";break;    case sparkPics[2]:ctx.strokeStyle="#8ff";break;    case sparkPics[3]:ctx.strokeStyle="#fff";break;    case sparkPics[4]:ctx.strokeStyle="#4f8";break;    case sparkPics[5]:ctx.strokeStyle="#f44";break;    case sparkPics[6]:ctx.strokeStyle="#f84";break;    case sparkPics[7]:ctx.strokeStyle="#84f";break;    case sparkPics[8]:ctx.strokeStyle="#fff";break;    case sparkPics[9]:ctx.strokeStyle="#44f";break;   }   for(j=sparks[i].trail.length-1;j>=0;--j){    point2=rasterizePoint(sparks[i].trail[j].x,sparks[i].trail[j].y,sparks[i].trail[j].z);    if(point2.d!=-1){    ctx.globalAlpha=j/sparks[i].trail.length*sparks[i].alpha/2;    ctx.beginPath();    ctx.moveTo(point1.x,point1.y);    ctx.lineWidth=1+sparks[i].radius*10/(sparks[i].trail.length-j)/(1+point2.d);    ctx.lineTo(point2.x,point2.y);    ctx.stroke();    point1.x=point2.x;    point1.y=point2.y;    }   }   }   ctx.globalAlpha=sparks[i].alpha;   ctx.drawImage(sparks[i].img,point.x-size/2,point.y-size/2,size,size);  }  } }   function frame(){    if(frames>100000){  seedTimer=0;  frames=0;  }  frames++;  draw();  doLogic();  requestAnimationFrame(frame); }   window.addEventListener("resize",()=>{  canvas.width=canvas.clientWidth;  canvas.height=canvas.clientHeight;  cx=canvas.width/2;  cy=canvas.height/2; });   initVars(); frame();</script> <div style="text-align:center;"> </div> </body> </html>