// You can find the Turtle API reference here: https://turtletoy.net/syntax
Canvas.setpenopacity(1);

const spiralCount = 4; //min=2 max=10 step=1
const zoom = .7; //min=.1 max=5 step=.1
const maxR = 90; //min=10 max=150 step=10
const direction = 0; //min=0 max=1 step=1 (Clockwise, Counter-clockwise)
const border = 5; //min=0 max=90 step=1
const drawBorder = 0; //min=0 max=1 step=1 (No, Yes)
const drawOutline = 1; //min=0 max=1 step=1 (No, Yes)
const hatching = 1; //min=0 max=3 step=1 (No, Ordered, Shuffled, Random)
const minHatch = .3; //min=.1 max=3 step=.1
const maxHatch = 1; //min=.1 max=3 step=.1

// Global code will be evaluated once.
const turtle = new Turtle();
const polygons = new Polygons();

const n = spiralCount;
const pi2 = Math.PI * 2;
const maxY = 30;
const spirals = [];
const spiralEnds = [];
const dir = direction == 0? 1: -1;
const hatchings = Array.apply(null,{length: n}).map((i, k) => [pi2 * (hatching == 3?Math.random():.15 + k / n), Math.max(minHatch, minHatch + ((maxHatch - minHatch) * (hatching == 3?Math.random():k / n)))]);
if(hatching==2) hatchings.sort(() => Math.random()-.5);

for(let i = 0; i < n; i++) {
    spirals[i] = [];
    spiralEnds[i] = [];
    let r = 0, t = pi2 * i / n;
    for(; r < maxR; r+=zoom, t+=.1) {
        spirals[i].push([Math.cos(t) * r, dir*Math.sin(t) * r]);
    }
    const maxT = t + (pi2 / n);
    for(; t < maxT; t+=.1) {
        spiralEnds[i].push([Math.cos(t) * r, dir*Math.sin(t) * r]);
    }
}

if(border != 0) {
    let pts = [[border-100,border-100],[100-border,border-100],[100-border,100-border],[border-100,100-border],[border-100,border-100],[-160, -160],[-160,160],[160, 160], [160, -160], [-160, -160]];
    const p = polygons.create();
    p.addPoints(...pts);
    polygons.draw(turtle, p);
    turtle.jump(pts[0]);
    if(drawBorder)pts.filter((i, k) => k < 5).map((i, k) => k == 0? turtle.jump(i):turtle.goto(i));
}

// The walk function will be called until it returns false.
function walk(i) {
    let next = (i + 1) % n;

    const p = polygons.create();
    p.addPoints(...spirals[i], ...spiralEnds[i], spiralEnds[next][0], ...spirals[next].slice(0).reverse());
    if(drawOutline == 1) p.addOutline();
    p.addHatching(...hatchings[i]);
    polygons.draw(turtle, p);

    return i < spirals.length - 1;
}

////////////////////////////////////////////////////////////////
// Polygon Clipping utility code - Created by Reinder Nijhoff 2019
// (Polygon binning by Lionel Lemarie 2021)
// https://turtletoy.net/turtle/a5befa1f8d
////////////////////////////////////////////////////////////////
function Polygons(){const t=[],s=25,e=Array.from({length:s**2},t=>[]),n=class{constructor(){this.cp=[],this.dp=[],this.aabb=[]}addPoints(...t){let s=1e5,e=-1e5,n=1e5,h=-1e5;(this.cp=[...this.cp,...t]).forEach(t=>{s=Math.min(s,t[0]),e=Math.max(e,t[0]),n=Math.min(n,t[1]),h=Math.max(h,t[1])}),this.aabb=[s,n,e,h]}addSegments(...t){t.forEach(t=>this.dp.push(t))}addOutline(){for(let t=0,s=this.cp.length;t<s;t++)this.dp.push(this.cp[t],this.cp[(t+1)%s])}draw(t){for(let s=0,e=this.dp.length;s<e;s+=2)t.jump(this.dp[s]),t.goto(this.dp[s+1])}addHatching(t,s){const e=new n;e.cp.push([-1e5,-1e5],[1e5,-1e5],[1e5,1e5],[-1e5,1e5]);const h=Math.sin(t)*s,o=Math.cos(t)*s,a=200*Math.sin(t),i=200*Math.cos(t);for(let t=.5;t<150/s;t++)e.dp.push([h*t+i,o*t-a],[h*t-i,o*t+a]),e.dp.push([-h*t+i,-o*t-a],[-h*t-i,-o*t+a]);e.boolean(this,!1),this.dp=[...this.dp,...e.dp]}inside(t){let s=0;for(let e=0,n=this.cp.length;e<n;e++)this.segment_intersect(t,[.1,-1e3],this.cp[e],this.cp[(e+1)%n])&&s++;return 1&s}boolean(t,s=!0){const e=[];for(let n=0,h=this.dp.length;n<h;n+=2){const h=this.dp[n],o=this.dp[n+1],a=[];for(let s=0,e=t.cp.length;s<e;s++){const n=this.segment_intersect(h,o,t.cp[s],t.cp[(s+1)%e]);!1!==n&&a.push(n)}if(0===a.length)s===!t.inside(h)&&e.push(h,o);else{a.push(h,o);const n=o[0]-h[0],i=o[1]-h[1];a.sort((t,s)=>(t[0]-h[0])*n+(t[1]-h[1])*i-(s[0]-h[0])*n-(s[1]-h[1])*i);for(let n=0;n<a.length-1;n++)(a[n][0]-a[n+1][0])**2+(a[n][1]-a[n+1][1])**2>=.001&&s===!t.inside([(a[n][0]+a[n+1][0])/2,(a[n][1]+a[n+1][1])/2])&&e.push(a[n],a[n+1])}}return(this.dp=e).length>0}segment_intersect(t,s,e,n){const h=(n[1]-e[1])*(s[0]-t[0])-(n[0]-e[0])*(s[1]-t[1]);if(0===h)return!1;const o=((n[0]-e[0])*(t[1]-e[1])-(n[1]-e[1])*(t[0]-e[0]))/h,a=((s[0]-t[0])*(t[1]-e[1])-(s[1]-t[1])*(t[0]-e[0]))/h;return o>=0&&o<=1&&a>=0&&a<=1&&[t[0]+o*(s[0]-t[0]),t[1]+o*(s[1]-t[1])]}};return{list:()=>t,create:()=>new n,draw:(n,h,o=!0)=>{reducedPolygonList=function(n){const h={},o=200/s;for(var a=0;a<s;a++){const c=a*o-100,r=[0,c,200,c+o];if(!(n[3]<r[1]||n[1]>r[3]))for(var i=0;i<s;i++){const c=i*o-100;r[0]=c,r[2]=c+o,n[0]>r[2]||n[2]<r[0]||e[i+a*s].forEach(s=>{const e=t[s];n[3]<e.aabb[1]||n[1]>e.aabb[3]||n[0]>e.aabb[2]||n[2]<e.aabb[0]||(h[s]=1)})}}return Array.from(Object.keys(h),s=>t[s])}(h.aabb);for(let t=0;t<reducedPolygonList.length&&h.boolean(reducedPolygonList[t]);t++);h.draw(n),o&&function(n){t.push(n);const h=t.length-1,o=200/s;e.forEach((t,e)=>{const a=e%s*o-100,i=(e/s|0)*o-100,c=[a,i,a+o,i+o];c[3]<n.aabb[1]||c[1]>n.aabb[3]||c[0]>n.aabb[2]||c[2]<n.aabb[0]||t.push(h)})}(h)}}}