// LL 2021

Canvas.setpenopacity(1);

const layers = 10; // min=1 max=100 step=1 
const size = 3;

const hatching = 1; // min=0 max=1 step=1 (No,Yes)
const style = 1; /// min=0 max=1 step=1 (Polygons (fast),Polygons (slow))
let polygons;

const turtle = new Turtle();

const left = -80, floor = 80;

function walk(i, t) {
    if (i == 0) {
        polygons = new Polygons();
    }
    
    const current_size = size * (layers - i);
    
    var list = [];
    for (var j=0; j<current_size; j++) { list.unshift("/"); list.push("\\"); }
    
    var height = 1;
    var path = [ list.shift() ];
    while (list.length > 0) {
        if (Math.random() > 0.5) { // && height < i) {
            path.push(list.shift());
            height++;
        } else {
            path.push(list.pop());
            height--;
        }
    }
    
    var x = left, y = floor;
    const length = 112 / current_size;
    const points = [ [x, y] ];
    while (path.length > 0) {
        const dir = path.shift();
        const angle = ((dir == "/") ? -1 : 1) * Math.PI / 4;
        x += Math.cos(angle) * length;
        y += Math.sin(angle) * length;
        points.push([x, Math.min(y, floor)]);
    }
    drawPoints(points, (layers - i/2) / layers);

    return (i+1) < layers;
}

function drawPoints(dpoints, h) {
    if (style == 0) {
        turtle.jump(dpoints[dpoints.length-1]);
        dpoints.forEach(p=>turtle.goto(p));
    } else {
        const p1 = polygons.create();
        p1.addPoints(...dpoints);
        p1.addOutline();
        if (hatching && h > 0) p1.addHatching(Math.random(), h);
        polygons.draw(turtle, p1, true);
    }
}

////////////////////////////////////////////////////////////////
// Polygon Clipping utility code - Created by Reinder Nijhoff 2019
// https://turtletoy.net/turtle/a5befa1f8d
////////////////////////////////////////////////////////////////
function Polygons(){let t=[];const s=class{constructor(){this.cp=[],this.dp=[],this.aabb=[]}addPoints(...t){let s=1e5,e=-1e5,h=1e5,i=-1e5;(this.cp=[...this.cp,...t]).forEach(t=>{s=Math.min(s,t[0]),e=Math.max(e,t[0]),h=Math.min(h,t[1]),i=Math.max(i,t[1])}),this.aabb=[(s+e)/2,(h+i)/2,(e-s)/2,(i-h)/2]}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,e){const h=new s;h.cp.push([-1e5,-1e5],[1e5,-1e5],[1e5,1e5],[-1e5,1e5]);const i=Math.sin(t)*e,n=Math.cos(t)*e,a=200*Math.sin(t),p=200*Math.cos(t);for(let t=.5;t<150/e;t++)h.dp.push([i*t+p,n*t-a],[i*t-p,n*t+a]),h.dp.push([-i*t+p,-n*t-a],[-i*t-p,-n*t+a]);h.boolean(this,!1),this.dp=[...this.dp,...h.dp]}inside(t){let s=0;for(let e=0,h=this.cp.length;e<h;e++)this.segment_intersect(t,[.13,-1e3],this.cp[e],this.cp[(e+1)%h])&&s++;return 1&s}boolean(t,s=!0){if(s&&Math.abs(this.aabb[0]-t.aabb[0])-(t.aabb[2]+this.aabb[2])>=0&&Math.abs(this.aabb[1]-t.aabb[1])-(t.aabb[3]+this.aabb[3])>=0)return this.dp.length>0;const e=[];for(let h=0,i=this.dp.length;h<i;h+=2){const i=this.dp[h],n=this.dp[h+1],a=[];for(let s=0,e=t.cp.length;s<e;s++){const h=this.segment_intersect(i,n,t.cp[s],t.cp[(s+1)%e]);!1!==h&&a.push(h)}if(0===a.length)s===!t.inside(i)&&e.push(i,n);else{a.push(i,n);const h=n[0]-i[0],p=n[1]-i[1];a.sort((t,s)=>(t[0]-i[0])*h+(t[1]-i[1])*p-(s[0]-i[0])*h-(s[1]-i[1])*p);for(let h=0;h<a.length-1;h++)(a[h][0]-a[h+1][0])**2+(a[h][1]-a[h+1][1])**2>=.001&&s===!t.inside([(a[h][0]+a[h+1][0])/2,(a[h][1]+a[h+1][1])/2])&&e.push(a[h],a[h+1])}}return(this.dp=e).length>0}segment_intersect(t,s,e,h){const i=(h[1]-e[1])*(s[0]-t[0])-(h[0]-e[0])*(s[1]-t[1]);if(0===i)return!1;const n=((h[0]-e[0])*(t[1]-e[1])-(h[1]-e[1])*(t[0]-e[0]))/i,a=((s[0]-t[0])*(t[1]-e[1])-(s[1]-t[1])*(t[0]-e[0]))/i;return n>=0&&n<=1&&a>=0&&a<=1&&[t[0]+n*(s[0]-t[0]),t[1]+n*(s[1]-t[1])]}};return{list:()=>t,create:()=>new s,draw:(s,e,h=!0)=>{for(let s=0;s<t.length&&e.boolean(t[s]);s++);e.draw(s),h&&t.push(e)}}}