SOURCE

function project3D(x,y,z,vars){

  var p,d;
  x-=vars.camX;
  y-=vars.camY;
  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=-9;
  var ry1=1;
  var rx2=9;
  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:Math.sqrt(x*x+y*y+z*z)
    };
  }else{
    return { d:-1 };
  }
}


function Vert(x,y,z){
  this.x = x;
  this.y = y;
  this.z = z;
}


function Poly(verts){
  this.verts = verts;
}


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)*256);
  var g = parseInt((0.5+Math.cos(col)*0.5)*256);
  var b = parseInt((0.5-Math.sin(col)*0.5)*256);
  return "#"+("0" + r.toString(16) ).slice (-2)+("0" + g.toString(16) ).slice (-2)+("0" + b.toString(16) ).slice (-2);
}


function process(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) / 20;
  t = Math.sin(vars.frameNo / 200) / 105;
  vars.camX = Math.sin(p + t) * d;
  vars.camZ = Math.cos(p + t) * d;
  vars.camY = -Math.sin(vars.frameNo / 100) *20;
  vars.yaw = Math.PI + p + t;
  vars.pitch = elevation(vars.camX, vars.camZ, vars.camY) - Math.PI / 2;

  for(var i=1;i<vars.shapes.length;++i){
    rotateShape(vars.shapes[i],0,0,0,0,.02*(i%2?-1:1),0);
  }
}


function sortFunction(a,b){
  return b.dist-a.dist;
}


function rotateShape(shape,ox,oy,oz,pitch,yaw){

  var p,d,x,y,z;
  x=shape.x-ox;
  y=shape.y-oy;
  z=shape.z-oz;
  d=Math.sqrt(y*y+z*z);
  p=Math.atan2(y,z);
  y=Math.sin(p+pitch)*d;
  z=Math.cos(p+pitch)*d;
  d=Math.sqrt(x*x+z*z);
  p=Math.atan2(x,z);
  x=Math.sin(p+yaw)*d;
  z=Math.cos(p+yaw)*d;
  shape.x=x+ox;
  shape.y=y+oy;
  shape.z=z+oz;

  for(var i=0;i<shape.polys.length;++i){
    for(var j=0;j<shape.polys[i].verts.length;++j){
      x=shape.polys[i].verts[j].x;
      y=shape.polys[i].verts[j].y;
      z=shape.polys[i].verts[j].z;
      d=Math.sqrt(y*y+z*z);
      p=Math.atan2(y,z);
      y=Math.sin(p+pitch)*d;
      z=Math.cos(p+pitch)*d;
      d=Math.sqrt(x*x+z*z);
      p=Math.atan2(x,z);
      x=Math.sin(p+yaw)*d;
      z=Math.cos(p+yaw)*d;
      shape.polys[i].verts[j].x=x;
      shape.polys[i].verts[j].y=y;
      shape.polys[i].verts[j].z=z;
    }
  }
}


function draw(vars){

  vars.ctx.globalAlpha=.25;
  vars.ctx.fillStyle="#000";
  vars.ctx.fillRect(0, 0, vars.canvas.width, vars.canvas.height);

  var pt,x,y,z,polys=[];

  for(var i=0;i<vars.shapes.length;++i){
    for(var j=0;j<vars.shapes[i].polys.length;++j){
      x=vars.shapes[i].x+vars.shapes[i].polys[j].verts[0].x;
      y=vars.shapes[i].y+vars.shapes[i].polys[j].verts[0].y;
      z=vars.shapes[i].z+vars.shapes[i].polys[j].verts[0].z;
      pt = project3D(x,y,z,vars);
      if(pt.d != -1){
        poly={};
        poly.verts=Array(vars.shapes[i].polys[j].verts.length);
        poly.dist=pt.d;
        poly.color=Math.PI*2/vars.shapes.length*i;
        poly.verts[0]={};
        poly.verts[0].x=pt.x;
        poly.verts[0].y=pt.y;
        for(var k=1;k<poly.verts.length;++k){
          x=vars.shapes[i].x+vars.shapes[i].polys[j].verts[k].x;
          y=vars.shapes[i].y+vars.shapes[i].polys[j].verts[k].y;
          z=vars.shapes[i].z+vars.shapes[i].polys[j].verts[k].z;
          pt = project3D(x,y,z,vars);
          poly.dist+=pt.d;
          poly.verts[k]={};
          poly.verts[k].x=pt.x;
          poly.verts[k].y=pt.y;
        }
        polys.push(poly);
      }
    }
  }
  polys.sort(sortFunction);
  for(var i=0;i<polys.length;++i){
    x=polys[i].verts[0].x;
    y=polys[i].verts[0].y;
    vars.ctx.lineWidth=100/(1+polys[i].dist);
    vars.ctx.beginPath();
    vars.ctx.moveTo(x,y);
    for(var j=1;j<polys[i].verts.length;++j){
      x=polys[i].verts[j].x;
      y=polys[i].verts[j].y;
      vars.ctx.lineTo(x,y);
    }
    vars.ctx.fillStyle=rgb(vars.frameNo/20+polys[i].color);
    vars.ctx.globalAlpha=.75;
    vars.ctx.fill();
    vars.ctx.strokeStyle="#fff";
    vars.ctx.globalAlpha=.8;
    vars.ctx.stroke();
  }
}

function Torus(x,y,z,radius1,radius2,stacks,slices,pitch,yaw){
  var shape={},x,y,z,p,x1,y1,z1,x2,y2,z2,x3,y3,z3,x4,y4,z4,p1,p2,d;
  shape.x=x;
  shape.y=y;
  shape.z=z;
  shape.polys=[];
  for(var j=0;j<slices;++j){
    for(var i=0;i<stacks;++i){
      p1=Math.PI*2/stacks*i;
      x1=radius2+Math.sin(p1)*radius1;
      y1=Math.cos(p1)*radius1;
      z1=0;
      d=Math.sqrt(x1*x1);
      p2=Math.PI*2/slices*j;
      p1=Math.atan2(x1,z1)+p2;
      x1=Math.sin(p1)*d;
      z1=Math.cos(p1)*d;

      p1=Math.PI*2/stacks*(i+1);
      x2=radius2+Math.sin(p1)*radius1;
      y2=Math.cos(p1)*radius1;
      z2=0;
      d=Math.sqrt(x2*x2);
      p2=Math.PI*2/slices*j;
      p1=Math.atan2(x2,z2)+p2;
      x2=Math.sin(p1)*d;
      z2=Math.cos(p1)*d;

      p1=Math.PI*2/stacks*(i+1);
      x3=radius2+Math.sin(p1)*radius1;
      y3=Math.cos(p1)*radius1;
      z3=0;
      d=Math.sqrt(x3*x3);
      p2=Math.PI*2/slices*(j+1);
      p1=Math.atan2(x3,z3)+p2;
      x3=Math.sin(p1)*d;
      z3=Math.cos(p1)*d;

      p1=Math.PI*2/stacks*i;
      x4=radius2+Math.sin(p1)*radius1;
      y4=Math.cos(p1)*radius1;
      z4=0;
      d=Math.sqrt(x4*x4);
      p2=Math.PI*2/slices*(j+1);
      p1=Math.atan2(x4,z4)+p2;
      x4=Math.sin(p1)*d;
      z4=Math.cos(p1)*d;

      shape.polys.push(new Poly([new Vert(x1,y1,z1),new Vert(x2,y2,z2),new Vert(x3,y3,z3),new Vert(x4,y4,z4)]));
    }
  }
  for(var i=0;i<shape.polys.length;++i){
    for(var j=0;j<shape.polys[i].verts.length;++j){
      x=shape.polys[i].verts[j].x;
      y=shape.polys[i].verts[j].y;
      z=shape.polys[i].verts[j].z;
      d=Math.sqrt(y*y+z*z);
      p=Math.atan2(y,z);
      y=Math.sin(p+pitch)*d;
      z=Math.cos(p+pitch)*d;
      d=Math.sqrt(x*x+z*z);
      p=Math.atan2(x,z);
      x=Math.sin(p+yaw)*d;
      z=Math.cos(p+yaw)*d;
      shape.polys[i].verts[j].x=x;
      shape.polys[i].verts[j].y=y;
      shape.polys[i].verts[j].z=z;
    }
  }
  return shape;
}


function loadScene(vars){

  vars.shapes=[];
  var x=0;
  var y=0;
  var z=0;
  var rad1=2;
  var rad2=10;
  var stacks=8;
  var slices=20;
  var pitch=0;
  var yaw=0;
  vars.shapes.push(Torus(x,y,z,rad1,rad2,stacks,slices,pitch,yaw));

  var sd=3,p;
  for(var i=0;i<sd;++i){
    p=Math.PI*2/sd*i;
    x=Math.sin(p)*rad2;
    z=Math.cos(p)*rad2;
    pitch=Math.PI/2;
    yaw=p+Math.PI/2;
    rad1b=1;
    rad2b=3.5*(i+1);
    stacks=6;
    slices=8*(i+1);
    vars.shapes.push(Torus(x,y,z,rad1b,rad2b,stacks,slices,pitch,yaw));
  }
}


function loadFloor(vars){

  var p1,p2,d=100;
  vars.floorTiles=[];
  for(var i=0;i<3500;++i){
    vert={};
    vert.p1=Math.PI*2*Math.random();
    vert.p2=Math.PI*Math.random();
    vert.x=Math.sin(vert.p1)*Math.sin(vert.p2)*d;
    vert.z=Math.cos(vert.p1)*Math.sin(vert.p2)*d;
    vert.y=Math.cos(vert.p2)*d;
    vars.floorTiles.push(vert);
  }
}


function frame(vars) {

  if(vars === undefined){
    var vars={};
    vars.canvas=document.createElement("canvas");
    document.body.appendChild(vars.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.canvas.oncontextmenu = function (e) { e.preventDefault(); };
    vars.canvas.addEventListener("mousemove", function(e){
      var rect = vars.canvas.getBoundingClientRect();
      vars.mx = Math.round((e.clientX-rect.left)/(rect.right-rect.left)*vars.canvas.width);
      vars.my = Math.round((e.clientY-rect.top)/(rect.bottom-rect.top)*vars.canvas.height);
    }, true);
    vars.canvas.addEventListener("mousedown", function(e){
      switch(e.which){
        case 1: vars.leftButton=1; break;
        case 3: vars.rightButton=1; break;
                    }
    }, true);
    vars.canvas.addEventListener("mouseup", function(e){
      switch(e.which){
        case 1: vars.leftButton=0; break;
        case 3: vars.rightButton=0; break;
                    }
    }, true);
    vars.canvas.addEventListener("mousewheel", function(e){
      var e = window.event || e; // old IE support
      vars.wheelDelta = Math.max(-1, Math.min(1, (e.wheelDelta/120 || -e.detail)));
    }, true);
    vars.canvas.addEventListener("touchstart", function(e){
      vars.leftButton=1;
      e.preventDefault();
      var rect = vars.canvas.getBoundingClientRect();
      vars.omx=vars.mx;
      vars.omy=vars.my;
      vars.mx = Math.round((e.changedTouches[0].pageX-rect.left)/(rect.right-rect.left)*vars.canvas.width);
      vars.my = Math.round((e.changedTouches[0].pageY-rect.top)/(rect.bottom-rect.top)*vars.canvas.height);
    }, true);
    vars.canvas.addEventListener("touchend", function(e){
      vars.leftButton=0;
    }, true);
    vars.canvas.addEventListener("touchmove", function(e){
      e.preventDefault();
      var rect = vars.canvas.getBoundingClientRect();
      vars.mx = Math.round((e.changedTouches[0].pageX-rect.left)/(rect.right-rect.left)*vars.canvas.width);
      vars.my = Math.round((e.changedTouches[0].pageY-rect.top)/(rect.bottom-rect.top)*vars.canvas.height);
    }, true);
    vars.frameNo=0;

    vars.camX = 0;
    vars.camY = 0;
    vars.camZ = -30;
    vars.pitch = 0;
    vars.yaw = 0;
    vars.cx=vars.canvas.width/2;
    vars.cy=vars.canvas.height/2;
    vars.scale=700;
    vars.seed=0;
    loadScene(vars);
    loadFloor(vars);
  }

  vars.frameNo++;
  requestAnimationFrame(function() {
    frame(vars);
  });

  process(vars);
  draw(vars);
}
frame();
html,body{
	margin:0px;
	width:100%;
	height:100%;
	overflow:hidden;
}

#canvas{
	position:absolute;
	width:100%;
	height:100%;
}
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