// script:  js
W=240;H=136;SZ=W*H;MW=W/2;MH=H/2;
PALETTE=0x3fc0;SCREEN=0x0000;HOFFSET=0x3ff9;abs=Math.abs;floor=Math.floor;max=Math.max;min=Math.min;sin=Math.sin;cos=Math.cos;rnd=Math.random;pow=Math.pow;sqrt=Math.sqrt;pi=Math.PI;tau=pi*2;function lerp(a,b,t){return a+(b-a)*t};function lin(sx,ex,sy,ey,t,cl=false){if (cl) {t=clamp(sx,ex,t);};return lerp(sy,ey,(t-sx)/(ex-sx))};function uf(a,b){return lerp(a,b,rnd())};function ri(mn,mx){return mn+floor(rnd()*(mx-mn+1))};function clamp(mn,mx,t){return max(min(mx,t),mn)};function ss(x){x=clamp(0,1,x);return x*x*(3.0-2.0*x)};function range(n){return Array.from(Array(n)).map((_,i)=>i)};function hsv2rgb(h,s,v){var h=(h%360); if (h<0){h=(h+360)%360;} let c=v*s; let x=c*(1-abs(((h/60)%2)-1)); let m=v-c; let [r,g,b]=[0,0,0]; if (h<60){[r,g]=[c,x];} else if (h<120){[r,g]=[x,c];} else if (h<180){[g,b]=[c,x];} else if (h<240){[g,b]=[x,c];} else if (h<300){[r,b]=[x,c];} else {[r,b]=[c,x];} return [r,g,b].map((x)=>(x+m)*255|0);};function pick(...vs){return vs[ri(0,vs.length-1)];};function hash(i){var s=floor(i);/*var s=i*747796405+2891336453;*/var w=((s>>((s>>28)+4))^s)*277803737;return (w>>22)^w;};
function viz_track(s=20,cl=false){vbank(1);if(cl){cls();};pix(0,0,11);pix(s,0,11);line(0,1,s*2,1,0);line(0,2,s*2,2,0);pix(le*s,1,12);pix(he*s,2,13);vbank(0);}
/* Finkel's Prelude:

min,max,abs,floor,pow,sin,cos,rnd
pi,tau,sqrt,hash

lerp,lin,uf,ri,clamp,ss,range,hsv2rgb
pick
*/


function BOOT(){
cls(0)
}

class P{
 constructor(x,y){
  this.x=x
  this.y=y
  this.ox=0
  this.oy=0
 }
 pos(t){
  return [
   this.x+this.ox*t,
   this.y+this.oy*t,
  ]
 }
 reset(){
  this.x+=this.ox
  this.y+=this.oy
  this.x=(this.x+nx)%nx
  this.y=(this.y+ny)%ny
  this.ox=0
  this.oy=0
 }
}

function reset(){
 vert=pick(true,false)
 n=vert?nx:ny
 dirs=range(n).map(_=>pick(-2,-1,-1,0,1,1,2))
 ps.forEach(p=>{
  p.reset()
  if (vert){
   p.oy=dirs[p.x]
  }
  else{
   p.ox=dirs[p.y]
  }
 })
}

nx=10
ny=8
ps=range(nx).flatMap(i=>{
 return range(ny).map(j=>new P(i,j))
})
reset()

bpm=120
spb=60/bpm
period=spb
lpt=0
function TIC(){
	vbank(1)
 cls(0)
	vbank(0)
 make_pal()

 secs=time()/1000
 pt=secs/period
 hpt=pt+0.5
 pt=pt%1
 hpt=hpt%1
 if (lpt>pt){
  reset()
 }
 ps.forEach((p,i)=>{
  if (i%2==0){
   return
  }
  t=pt
  t*=1
  t=clamp(0,1,t)
  t=pow(t,0.2)
  var [x,y]=p.pos(t)
  s=24
  m=2
  //rect(x*s,y*s,s-m,s-m,i)
  w=0.9
  ocs=[[x,y],[x+w,y],[x+w,y+w],[x,y+w]]
  tcs=ocs.map(pp=>{
   var x=pp[0]
   var y=pp[1]
   th=lin(0,nx,0,tau,x)
   phi=lin(0,ny,0,tau,y)
   r=30+20*sin(phi)
   return [MW+sin(th)*r*2,MH-cos(th)*r*1.4]
  })
  rs=ocs.map(pp=>{
   var y=pp[1]
   phi=lin(0,ny,0,tau,y)
   return sin(phi)
  })
  if (rs[0]>rs[2]){
   return
  }
  vbank(1)
  col=12
  line(...tcs[0],...tcs[1],col)
  line(...tcs[1],...tcs[2],col)
  line(...tcs[2],...tcs[3],col)
  line(...tcs[3],...tcs[0],col)
  vbank(0)
  ix=hash(i+floor(time()))%2
  col=ix==0?0:15
  col=15
  if (hpt<0.1&&ix){
	  tri(...tcs[0],...tcs[1],...tcs[2],col)
	  tri(...tcs[0],...tcs[3],...tcs[2],col)
  }
 })
 lpt=pt
 vbank(0)
 for(i=0;i<SZ;i++){
  v=peek4(i)
  if (v==0){
   continue
  }
  if (rnd()>0.1){
	  poke4(i,v-1)
  }
 }
}

function make_pal(){
 t=time()/2000
 r=lin(-1,1,0.5,2,sin(t))
 g=lin(-1,1,0.5,2,sin(t+tau/3))
 b=lin(-1,1,0.5,2,sin(t+tau/3*2))
 range(16).flatMap(i=>{
  x=i/15.0
  return [
   pow(x,r)*255,
   pow(x,g)*255,
   pow(x,b)*255,
  ]
 }).forEach((c,i)=>{
  poke(PALETTE+i,c)
 })
}