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JS如何實現超好看的3D煙火特效？（程式碼範例）

青灯夜游轉載: 2020-06-12 10:09:453228瀏覽

這篇文章給大家透過實例介紹一下使用JS如何實現實現超好看的3D煙火特效？有一定的參考價值，有需要的朋友可以參考一下，希望對大家有幫助。

廢話不多說，直接上程式碼：

<!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>

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