// Forked from "Polygon hatching" by reinder
// https://turtletoy.net/turtle/92ebe08d89

// Polygon delegated hatching and deferred drawing. Created by Jurgen Westerhof 2024
// 
// https://turtletoy.net/turtle/d1095a7e5d
//
// Original:
//
// Polygon hatching. Created by Reinder Nijhoff 2018
// @reindernijhoff
//
// https://turtletoy.net/turtle/92ebe08d89
//
// You can find the Turtle API reference here: https://turtletoy.net/syntax
Canvas.setpenopacity(.6);

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

const hatchings = Array.from({length: 3}).map((e,i) => new LineHatching((i-1/3)*Math.PI/2, .3+i*.5, .3));

function walk(i) {
    const s = 25;
    const sp = 12.5;

    // first an invisible cube is added to the clip list.
    //if (i ==0) drawCube((3-8/2)*(s+sp),2*s-(s+sp)*(-8+9)/Math.sqrt(1.25),s,0,false);
    
    if (i < 4)  drawCube((i-1.5)*(s+sp),2*s,s);
    else if (i < 7)  drawCube((3-i/2)*(s+sp),2*s-(s+sp)*(i-3)/Math.sqrt(1.25),s);
    else if (i < 9)  drawCube((3-i/2)*(s+sp),2*s-(s+sp)*(-i+9)/Math.sqrt(1.25),s);//,9);
    
    if(i == 2) {
        polygons.stopDeferring();
    } else if(i == 9) {
        polygons.finalizeDeferSession(turtle);
    }
    return i < 9;
}

function drawCube(x,y,r) { //,skip=0,draw=true) {
    const p = [[x,y]];
    for (let i=0; i<6; i++) {
        p.push([Math.cos(i*Math.PI/3)*r+x, Math.sin(i*Math.PI/3)*r+y]);
    }
    // create 3 visible polygons for cube
    const ps = [];
    for (let i=0; i<3; i++) {
        const c = polygons.create();
        c.addPoints(p[0],p[i*2+1],p[i*2+2],p[(i*2+3)%6]);
        c.addOutline();
        c.addHatching(hatchings[i]);
        polygons.draw(turtle, c);
    }
}

///////////////////////////////////////////////////////////////////
// This is only the part of the Polygon Hatching utility code
// required in this turtle. For the full hatchery code see
// https://turtletoy.net/turtle/d068ad6040
//
///////////////////////////////////////////////////////////////////
// Polygon Hatching utility code - Created by Jurgen Westerhof 2024
// https://turtletoy.net/turtle/d068ad6040
// ////////////////////////////////////////////////////////////////
// // To be used with modified Polygon Clipping utility code
// //            Orginal: https://turtletoy.net/turtle/a5befa1f8d
// //    Polygon binning: https://turtletoy.net/turtle/95f33bd383
// // Delegated Hatching: https://turtletoy.net/turtle/d068ad6040
///////////////////////////////////////////////////////////////////
function loadHatcheryNamespace() {
    //for convenience on Turtletoy you can click the arrow to the right of the line number to collapse a class
    //////////////////////////////////////////////////// root
    class PolygonHatching {
        constructor() {
            if (this.constructor === PolygonHatching) {
                throw new Error("PolygonHatching is an abstract class and can't be instantiated.");
            }
            
            this.minX = -100;
            this.minY = -100;
            this.maxX = 100;
            this.maxY = 100;
            this.width = 200;
            this.height = 200;
            
            this.segments = [];
            
            this.init();
        }
        hatch(polygonsClass, thePolygonToHatch) {
            const e = new polygonsClass;
            e.cp.push(...thePolygonToHatch.aabb);//[-1e5,-1e5],[1e5,-1e5],[1e5,1e5],[-1e5,1e5]);
            
            this.addHatchSegments(e.dp);
            
            e.boolean(thePolygonToHatch,!1);
            thePolygonToHatch.dp=[...thePolygonToHatch.dp,...e.dp]
        }
        addHatchSegments(segments) {
            this.getSegments().forEach(e => segments.push(e));
        }
        getSegments() { return this.segments; }
        init() {
            ///////////////////////////////////////////////////////
            // Vector functions - Created by Jurgen Westerhof 2024
            // https://turtletoy.net/turtle/d068ad6040
            ///////////////////////////////////////////////////////
            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 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)); }
            }
            this.V = Vector;
            
            class Intersection2D {
                //a-start, a-direction, b-start, b-direction
                //returns false on no intersection or [[intersection:x,y], scalar a-direction, scalar b-direction
                static info(as, ad, bs, bd) {
                    const d = V.sub(bs, as), det = -V.det([bd, ad]);
                    if(det === 0) return false;
                    const res = [V.det([d, bd]) / det, V.det([d, ad]) / det];
                    return [V.add(as, V.scale(ad, res[0])), ...res];
                }
                static ray(a, b, c, d) {
                    return this.info(a, b, c, d);
                }
                static segment(a,b,c,d, inclusiveStart = true, inclusiveEnd = true) {
                    const i = this.info(a, V.sub(b, a), c, V.sub(d, c));
                    return i === false? false: (
                        (inclusiveStart? 0<=i[1] && 0<=i[2]: 0<i[1] && 0<i[2])
                     && (inclusiveEnd?   i[1]<=1 && i[2]<=1: i[1]<1 && i[2]<1)
                    )?i[0]:false;
                }
            }
            this.Intersection = Intersection2D;
        }
    }
    this.PolygonHatching = PolygonHatching;
    class LineHatching extends PolygonHatching {
        constructor(angle, distance, inp = 0) {
            super();
            
            const h=Math.sin(angle)*distance,o=Math.cos(angle)*distance,a=200*Math.sin(angle),i=200*Math.cos(angle);
            this.segments = Array.from({length: 150/distance}).flatMap((x,y,z,t=.5+y) => [
                [h*t+i+inp*(Math.random()-.5),o*t-a+inp*(Math.random()-.5)],[h*t-i+inp*(Math.random()-.5),o*t+a+inp*(Math.random()-.5)], [-h*t+i+inp*(Math.random()-.5),-o*t-a+inp*(Math.random()-.5)],[-h*t-i+inp*(Math.random()-.5),-o*t+a+inp*(Math.random()-.5)]
            ])
        }
    }
    this.LineHatching = LineHatching;
}

////////////////////////////////////////////////////////////////
// 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;}}}