const randomSeed = 'Change me'; //type=string
const grid = 20; //min=2 max=30 step=2
const minW = 0; //min=0 max=1 step=.01
const minH = .4; //min=0 max=1 step=.01
const th = .2; //min=0 max=1 step=.01
const shape = 0; //min=0 max=2 step=1 (L, N, U)

// You can find the Turtle API reference here: https://turtletoy.net/syntax
Canvas.setpenopacity(1);
// Global code will be evaluated once.
turtlelib_init();
randomSeed == ''? R.seedRandom(): R.seed(randomSeed);
const turtle = new Turtle();
const polygons = new Polygons();
const lerp = (a, b, t) => a - a*t + b * t;
const shapePts = (t = 1, minW = 0, minH = .4, th = .2, shape = 0) => {
    const thick = th * t;
    const curW = (1 - (1 - t) * (1 - minW)) * .5;
    const curH = (1 - (1 - t) * (1 - minH)) * .5;
    switch(shape) {
        case 1: return [ //N
            [curW, -curH], [curW, curH], [curW - thick - thick, curH],
            [-curW + thick, thick-curH],
            [-curW + thick, curH], [-curW, curH], [-curW , -curH],
            [-curW + thick + thick, -curH], [curW-thick,curH-thick], [curW-thick, -curH]
        ];
        case 2: return [ //U
            [curW, -curH], [curW, curH], [-curW, curH], [-curW, -curH], 
            [thick - curW, -curH], [thick - curW, curH - thick], [curW - thick, curH - thick], [curW - thick, -curH],
        ];
        default: return [ //L
            [curW, -curH], [curW, curH], [-curW, curH],
            [-curW, curH - thick], [curW - thick, curH - thick], [curW - thick, -curH]
        ];
    }
}
const cellWidth = 200/grid;


// The walk function will be called until it returns false.
function walk(i) {
    const col = i % grid;
    const row = i / grid | 0;
    
    const upperHalf = row < grid/2;
    const path = shapePts(
        upperHalf? lerp(.15, 1,  row          /(grid/2-1)):
                   lerp(1, .15, (row-(grid/2))/(grid/2-1)),
    minW, minH, th, shape).map(pt => V.scale(pt, cellWidth));

    const p = polygons.create();
    const rot = V.rot2d(Math.PI * (Math.random() * 4 |0) / 2);
    p.addPoints(...path.map(pt => V.trans(rot, pt)).map(pt => V.add(pt, [(.5 + col)*cellWidth-100, (.5 + row)*cellWidth-100])));
    if(upperHalf) p.addHatching(1, .15);
    polygons.draw(turtle, p);
    
    if(!upperHalf) {
        //add background black
        const pp = polygons.create();
        pp.addPoints(...[[-.5, -.5], [.5, -.5], [.5, .5], [-.5, .5]].map(pt => V.scale(pt, cellWidth)).map(pt => V.add(pt, [(.5 + col)*cellWidth-100, (.5 + row)*cellWidth-100])));
        pp.addHatching(1, .15);
        polygons.draw(turtle, pp);
    }

    return i < grid**2 - 1;
}

// Below is automatically maintained by Turtlelib 1.0
// Changes below this comment might interfere with its correct functioning.
function turtlelib_init() {
	turtlelib_ns_80dcba45dd_Jurgen_Polygons();
	turtlelib_ns_c6665b0e9b_Jurgen_Vector_Math();
	turtlelib_ns_13b81fd40e_Jurgen_Randomness();
}
// Turtlelib Jurgen Polygons v 1 - start - {"id":"80dcba45dd","package":"Jurgen","name":"Polygons","version":"1"}
function turtlelib_ns_80dcba45dd_Jurgen_Polygons() {
////////////////////////////////////////////////////////////////
// Polygon Clipping utility code - Created by Reinder Nijhoff 2019
// (Polygon binning by Lionel Lemarie 2021) https://turtletoy.net/turtle/95f33bd383
// (Delegated Hatching by Jurgen Westerhof 2024) https://turtletoy.net/turtle/d068ad6040
// (Deferred Polygon Drawing by Jurgen Westerhof 2024) https://turtletoy.net/turtle/6f3d2bc0b5
// https://turtletoy.net/turtle/a5befa1f8d
//
// const polygons = new Polygons();
// const p = polygons.create();
// polygons.draw(turtle, p);
// polygons.list();
// polygons.startDeferSession();
// polygons.stopDeferring();
// polygons.finalizeDeferSession(turtle);
//
// p.addPoints(...[[x,y],]);
// p.addSegments(...[[x,y],]);
// p.addOutline();
// p.addHatching(angle, distance); OR p.addHatching(HatchObject); where HatchObject has a method 'hatch(PolygonClass, thisPolygonInstance)'
// p.inside([x,y]);
// p.boolean(polygon, diff = true);
// p.segment_intersect([x,y], [x,y], [x,y], [x,y]);
////////////////////////////////////////////////////////////////
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) {if(typeof t == 'object') return t.hatch(n, this);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])]}};const y=function(n,j=[]){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]||j.includes(s)||(h[s]=1)})}}return Array.from(Object.keys(h),s=>t[s])};return{list:()=>t,create:()=>new n,draw:(n,h,o=!0)=>{rpl=y(h.aabb, this.dei === undefined? []: Array.from({length: t.length - this.dei}).map((e, i) => this.dsi + i));for(let t=0;t<rpl.length&&h.boolean(rpl[t]);t++);const td=n.isdown();if(this.dsi!==undefined&&this.dei===undefined)n.pu();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);if(td)n.pd();},startDeferSession:()=>{if(this.dei!==undefined)throw new Error('Finalize deferring before starting new session');this.dsi=t.length;},stopDeferring:()=>{if(this.dsi === undefined)throw new Error('Start deferring before stopping');this.dei=t.length;},finalizeDeferSession:(n)=>{if(this.dei===undefined)throw new Error('Stop deferring before finalizing');for(let i=this.dsi;i<this.dei;i++) {rpl = y(t[i].aabb,Array.from({length:this.dei-this.dsi+1}).map((e,j)=>i+j));for(let j=0;j<rpl.length&&t[i].boolean(rpl[j]);j++);t[i].draw(n);}this.dsi=undefined;this.dei=undefined;}}}
this.Polygons = Polygons;
}
// Turtlelib Jurgen Polygons v 1 - end
// Turtlelib Jurgen Vector Math v 4 - start - {"id":"c6665b0e9b","package":"Jurgen","name":"Vector Math","version":"4"}
function turtlelib_ns_c6665b0e9b_Jurgen_Vector_Math() {
/////////////////////////////////////////////////////////
// Vector functions - Created by Jurgen Westerhof 2024 //
/////////////////////////////////////////////////////////
class Vector {
    static add  (a,b) { return a.map((v,i)=>v+b[i]); }
    static sub  (a,b) { return a.map((v,i)=>v-b[i]); }
    static mul  (a,b) { return a.map((v,i)=>v*b[i]); }
    static div  (a,b) { return a.map((v,i)=>v/b[i]); }
    static scale(a,s) { return a.map(v=>v*s); }

    static det(m)                { return m.length == 1? m[0][0]: m.length == 2 ? m[0][0]*m[1][1]-m[0][1]*m[1][0]: m[0].reduce((r,e,i) => r+(-1)**(i+2)*e*this.det(m.slice(1).map(c => c.filter((_,j) => i != j))),0); }
    static angle(a)              { return Math.PI - Math.atan2(a[1], -a[0]); } //compatible with turtletoy heading
    static rot2d(angle)          { return [[Math.cos(angle), -Math.sin(angle)], [Math.sin(angle), Math.cos(angle)]]; }
    static rot3d(yaw,pitch,roll) { return [[Math.cos(yaw)*Math.cos(pitch), Math.cos(yaw)*Math.sin(pitch)*Math.sin(roll)-Math.sin(yaw)*Math.cos(roll), Math.cos(yaw)*Math.sin(pitch)*Math.cos(roll)+Math.sin(yaw)*Math.sin(roll)],[Math.sin(yaw)*Math.cos(pitch), Math.sin(yaw)*Math.sin(pitch)*Math.sin(roll)+Math.cos(yaw)*Math.cos(roll), Math.sin(yaw)*Math.sin(pitch)*Math.cos(roll)-Math.cos(yaw)*Math.sin(roll)],[-Math.sin(pitch), Math.cos(pitch)*Math.sin(roll), Math.cos(pitch)*Math.cos(roll)]]; }
    static trans(matrix,a)       { return a.map((v,i) => a.reduce((acc, cur, ci) => acc + cur * matrix[ci][i], 0)); }
    //Mirror vector a in a ray through [0,0] with direction mirror
    static mirror2d(a,mirror)    { return [Math.atan2(...mirror)].map(angle => this.trans(this.rot2d(angle), this.mul([-1,1], this.trans(this.rot2d(-angle), a)))).pop(); }

    static equals(a,b)   { return !a.some((e, i) => e != b[i]); }
    static approx(a,b,p) { return this.len(this.sub(a,b)) < (p === undefined? .001: p); }
    static norm  (a)     { return this.scale(a,1/this.len(a)); }
    static len   (a)     { return Math.hypot(...a); }
    static lenSq (a)     { return a.reduce((a,c)=>a+c**2,0); }
    static lerp  (a,b,t) { return a.map((v, i) => v*(1-t) + b[i]*t); }
    static dist  (a,b)   { return Math.hypot(...this.sub(a,b)); }
    
    static dot  (a,b)   { return a.reduce((a,c,i) => a+c*b[i], 0); }
    static cross(...ab) { return ab[0].map((e, i) => ab.map(v => v.filter((ee, ii) => ii != i))).map((m,i) => (i%2==0?-1:1)*this.det(m)); }
    
    static clamp(a,min,max) { return a.map((e,i) => Math.min(Math.max(e, min[i]), max[i])) };
    static rotateClamp(a,min,max) { return a.map((e,i) => {const d = max[i]-min[i];if(d == 0) return min[i];while(e < min[i]) { e+=d; }while(e > max[i]) { e-=d; }return e;});
    }
}
this.V = Vector;
}
// Turtlelib Jurgen Vector Math v 4 - end
// Turtlelib Jurgen Randomness v 2 - start - {"id":"13b81fd40e","package":"Jurgen","name":"Randomness","version":"2"}
function turtlelib_ns_13b81fd40e_Jurgen_Randomness() {
///////////////////////////////////////////////////////////////
// Pseudorandom functions - Created by Jurgen Westerhof 2024 //
///////////////////////////////////////////////////////////////
class Random {
    static #apply(seed) {
        // Seedable random number generator by David Bau: http://davidbau.com/archives/2010/01/30/random_seeds_coded_hints_and_quintillions.html
        !function(a,b,c,d,e,f,g,h,i){function j(a){var b,c=a.length,e=this,f=0,g=e.i=e.j=0,h=e.S=[];for(c||(a=[c++]);d>f;)h[f]=f++;for(f=0;d>f;f++)h[f]=h[g=s&g+a[f%c]+(b=h[f])],h[g]=b;(e.g=function(a){for(var b,c=0,f=e.i,g=e.j,h=e.S;a--;)b=h[f=s&f+1],c=c*d+h[s&(h[f]=h[g=s&g+b])+(h[g]=b)];return e.i=f,e.j=g,c})(d)}function k(a,b){var c,d=[],e=typeof a;if(b&&"object"==e)for(c in a)try{d.push(k(a[c],b-1))}catch(f){}return d.length?d:"string"==e?a:a+"\0"}function l(a,b){for(var c,d=a+"",e=0;e<d.length;)b[s&e]=s&(c^=19*b[s&e])+d.charCodeAt(e++);return n(b)}function m(c){try{return o?n(o.randomBytes(d)):(a.crypto.getRandomValues(c=new Uint8Array(d)),n(c))}catch(e){return[+new Date,a,(c=a.navigator)&&c.plugins,a.screen,n(b)]}}function n(a){return String.fromCharCode.apply(0,a)}var o,p=c.pow(d,e),q=c.pow(2,f),r=2*q,s=d-1,t=c["seed"+i]=function(a,f,g){var h=[];f=1==f?{entropy:!0}:f||{};var o=l(k(f.entropy?[a,n(b)]:null==a?m():a,3),h),s=new j(h);return l(n(s.S),b),(f.pass||g||function(a,b,d){return d?(c[i]=a,b):a})(function(){for(var a=s.g(e),b=p,c=0;q>a;)a=(a+c)*d,b*=d,c=s.g(1);for(;a>=r;)a/=2,b/=2,c>>>=1;return(a+c)/b},o,"global"in f?f.global:this==c)};if(l(c[i](),b),g&&g.exports){g.exports=t;try{o=require("crypto")}catch(u){}}else h&&h.amd&&h(function(){return t})}(this,[],Math,256,6,52,"object"==typeof module&&module,"function"==typeof define&&define,"random");
        Math.seedrandom(seed);
    }
    static seedRandom() { this.#apply(new Date().getMilliseconds()); }
    static seedDaily() { this.#apply(new Date().toDateString()); }
    static seed(seed) { this.#apply(seed); }
    static getInt(min, max) { if(max == undefined) {max = min + 1; min = 0; } const [mi, ma] = [Math.min(min, max), Math.max(min, max)]; return (mi + Math.random() * (ma - mi)) | 0;}
    static get(min, max) {if(min == undefined) {return Math.random();}if(max == undefined) {max = min;min = 0;}const [mi, ma] = [Math.min(min, max), Math.max(min, max)];return mi + Math.random() * (ma - mi);}
    static fraction(whole) { return this.get(0, whole); }
    static getAngle(l = 1) { return l * this.get(0, 2*Math.PI); }
    // Standard Normal variate using Box-Muller transform.
    static getGaussian(mean=.5, stdev=.1) {const u = 1 - this.get(); /* Converting [0,1) to (0,1] */const v = this.get();const z = ( -2.0 * Math.log( u ) )**.5 * Math.cos( 2.0 * Math.PI * v );/* Transform to the desired mean and standard deviation: */return z * stdev + mean;}
    static skew(value, skew = 0) { /*skew values (from 0 to 1) by a skew from -1 to 1, respectively right and left skewed (resp more values to left or to right), 0 is not skewed*/return (skew < 0)? value - (this.skew(1-value, -skew) - (1-value)): Math.pow(value, 1-Math.abs(skew));}
    static getNormalDistributed(skew = 0) { /*skew values (from 0 to 1) by a skew from -1 to 1, respectively right and left skewed (resp more values to left or to right), 0 is not skewed*/let v = -1;while(v < 0 || 1 <= v) { v = this.getGaussian(.5, .1) };return this.skew(v, skew);}
}
this.R = Random;
}
// Turtlelib Jurgen Randomness v 2 - end