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warpspeed.js
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warpspeed.js
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window.requestAnimationFrame=window.requestAnimationFrame||(function(callback,element){setTimeout(callback,1000/60);});
function timeStamp(){
if(window.performance.now)return window.performance.now(); else return Date.now();
}
function isVisible(el){
var r = el.getBoundingClientRect();
return r.top+r.height >= 0 &&r.left+r.width >= 0 &&r.bottom-r.height <= (window.innerHeight || document.documentElement.clientHeight) && r.right-r.width <= (window.innerWidth || document.documentElement.clientWidth);
}
function Star(x,y,z){
this.x=x;
this.y=y;
this.z=z;
this.size=0.5+Math.random();
}
function WarpSpeed(targetId,config){
this.targetId=targetId;
if(WarpSpeed.RUNNING_INSTANCES==undefined)WarpSpeed.RUNNING_INSTANCES={};
if(WarpSpeed.RUNNING_INSTANCES[targetId]){WarpSpeed.RUNNING_INSTANCES[targetId].destroy();}
config=config||{};
if(typeof config == "string")try{config=JSON.parse(config);}catch(e){config={}}
this.SPEED=config.speed==undefined||config.speed<0?0.7:config.speed;
this.TARGET_SPEED=config.targetSpeed==undefined||config.targetSpeed<0?this.SPEED:config.targetSpeed;
this.SPEED_ADJ_FACTOR=config.speedAdjFactor==undefined?0.03:config.speedAdjFactor<0?0:config.speedAdjFactor>1?1:config.speedAdjFactor;
this.DENSITY=config.density==undefined||config.density<=0?0.7:config.density;
this.USE_CIRCLES=config.shape==undefined?true:config.shape=="circle";
this.DEPTH_ALPHA=config.depthFade==undefined?true:config.depthFade;
this.WARP_EFFECT=config.warpEffect==undefined?true:config.warpEffect;
this.WARP_EFFECT_LENGTH=config.warpEffectLength==undefined?5:config.warpEffectLength<0?0:config.warpEffectLength;
this.STAR_SCALE=config.starSize==undefined||config.starSize<=0?3:config.starSize;
this.BACKGROUND_COLOR=config.backgroundColor==undefined?"hsl(263,45%,7%)":config.backgroundColor;
var canvas=document.getElementById(this.targetId);
canvas.width=1; canvas.height=1;
var ctx=canvas.getContext("2d");
ctx.fillStyle=this.BACKGROUND_COLOR;
ctx.fillRect(0,0,1,1);
ctx.fillStyle=config.starColor==undefined?"#FFFFFF":config.starColor;
ctx.fillRect(0,0,1,1);
var color=ctx.getImageData(0,0,1,1).data;
this.STAR_R=color[0]; this.STAR_G=color[1]; this.STAR_B=color[2];
this.prevW=-1; this.prevH=-1; //width and height will be set at first draw call
this.stars=[];
for(var i=0;i<this.DENSITY*1000;i++){
this.stars.push(new Star((Math.random()-0.5)*1000,(Math.random()-0.5)*1000,1000*Math.random()));
}
this.lastMoveTS=timeStamp();
this.drawRequest=null;
this.LAST_RENDER_T=0;
WarpSpeed.RUNNING_INSTANCES[targetId]=this;
this.draw();
}
WarpSpeed.prototype={
constructor:WarpSpeed,
draw:function(){
var TIME=timeStamp();
if(!(document.getElementById(this.targetId))){
this.destroy();
return;
}
this.move();
var canvas=document.getElementById(this.targetId);
if(!this.PAUSED&&isVisible(canvas)){
if(this.prevW!=canvas.clientWidth||this.prevH!=canvas.clientHeight){
canvas.width=(canvas.clientWidth<10?10:canvas.clientWidth)*(window.devicePixelRatio||1);
canvas.height=(canvas.clientHeight<10?10:canvas.clientHeight)*(window.devicePixelRatio||1);
}
this.size=(canvas.height<canvas.width?canvas.height:canvas.width)/(10/(this.STAR_SCALE<=0?0:this.STAR_SCALE));
if(this.WARP_EFFECT) this.maxLineWidth=this.size/30;
var ctx=canvas.getContext("2d");
ctx.fillStyle=this.BACKGROUND_COLOR;
ctx.fillRect(0,0,canvas.width,canvas.height);
var rgb="rgb("+this.STAR_R+","+this.STAR_G+","+this.STAR_B+")", rgba="rgba("+this.STAR_R+","+this.STAR_G+","+this.STAR_B+",";
for(var i=0;i<this.stars.length;i++){
var s=this.stars[i];
var xOnDisplay=s.x/s.z, yOnDisplay=s.y/s.z;
if(!this.WARP_EFFECT&&(xOnDisplay<-0.5||xOnDisplay>0.5||yOnDisplay<-0.5||yOnDisplay>0.5))continue;
var size=s.size*this.size/s.z;
if(size<0.3) continue; //don't draw very small dots
if(this.DEPTH_ALPHA){
var alpha=(1000-s.z)/1000;
ctx.fillStyle=rgba+(alpha>1?1:alpha)+")";
}else{
ctx.fillStyle=rgb;
}
if(this.WARP_EFFECT){
ctx.beginPath();
var x2OnDisplay=s.x/(s.z+this.WARP_EFFECT_LENGTH*this.SPEED), y2OnDisplay=s.y/(s.z+this.WARP_EFFECT_LENGTH*this.SPEED);
if(x2OnDisplay<-0.5||x2OnDisplay>0.5||y2OnDisplay<-0.5||y2OnDisplay>0.5)continue;
ctx.moveTo(canvas.width*(xOnDisplay+0.5)-size/2,canvas.height*(yOnDisplay+0.5)-size/2);
ctx.lineTo(canvas.width*(x2OnDisplay+0.5)-size/2,canvas.height*(y2OnDisplay+0.5)-size/2);
ctx.lineWidth=size>this.maxLineWidth?this.maxLineWidth:size;
if(this.USE_CIRCLES){ctx.lineCap="round";}else{ctx.lineCap="butt"}
ctx.strokeStyle=ctx.fillStyle;
ctx.stroke();
}else if(this.USE_CIRCLES){
ctx.beginPath();
ctx.arc(canvas.width*(xOnDisplay+0.5)-size/2,canvas.height*(yOnDisplay+0.5)-size/2,size/2,0,2*Math.PI);
ctx.fill();
}else{
ctx.fillRect(canvas.width*(xOnDisplay+0.5)-size/2,canvas.height*(yOnDisplay+0.5)-size/2,size,size);
}
}
this.prevW=canvas.clientWidth;
this.prevH=canvas.clientHeight;
}
if(this.drawRequest!=-1)this.drawRequest=requestAnimationFrame(this.draw.bind(this));
this.LAST_RENDER_T=timeStamp()-TIME;
},
move:function(){
var t=timeStamp(), speedMulF=(t-this.lastMoveTS)/(1000/60);
this.lastMoveTS=t;
if(this.PAUSED)return;
var speedAdjF=Math.pow(this.SPEED_ADJ_FACTOR<0?0:this.SPEED_ADJ_FACTOR>1?1:this.SPEED_ADJ_FACTOR,1/speedMulF);
this.SPEED=this.TARGET_SPEED*speedAdjF+this.SPEED*(1-speedAdjF);
if(this.SPEED<0)this.SPEED=0;
var speed=this.SPEED*speedMulF;
for(var i=0;i<this.stars.length;i++){
var s=this.stars[i];
s.z-=speed;
while(s.z<1){
s.z+=1000;
s.x=(Math.random()-0.5)*s.z;
s.y=(Math.random()-0.5)*s.z;
}
}
},
destroy:function(targetId){
if(targetId){
if(WarpSpeed.RUNNING_INSTANCES[targetId])WarpSpeed.RUNNING_INSTANCES[targetId].destroy();
}else{
try{cancelAnimationFrame(this.drawRequest);}catch(e){this.drawRequest=-1;}
WarpSpeed.RUNNING_INSTANCES[this.targetId]=undefined;
}
},
pause:function(){
this.PAUSED=true;
},
resume:function(){
this.PAUSED=false;
}
}
WarpSpeed.destroy=WarpSpeed.prototype.destroy;