const width = 5.4; //min=.1 max=7 step=.1

// You can find the Turtle API reference here: https://turtletoy.net/syntax
Canvas.setpenopacity(.7);

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

const ratio = Math.cos(Math.PI * 30/180);

turtle.pu();
turtle.jump(-50, ratio * -70);
const corePositions = Array.from({length: 3}).flatMap(a => [100, 140].map(t => {turtle.forward(t);turtle.right(120);return turtle.pos();})).map((v, i, a) => a[(i+2)%a.length])
turtle.jump(-60, ratio * -50);
const trianglePositions = Array.from({length: 3}).map(a => {turtle.forward(120); turtle.right(120); return turtle.pos();}).map((v, i, a) => a[(i+2)%a.length])
turtle.pd();

const connectIntersections = (v, i, arr) => [intersect_ray2(v[0], v[1], arr[(i - 1 + arr.length) % arr.length][0], arr[(i - 1 + arr.length) % arr.length][1])].map(t => [t, sub2(intersect_ray2(v[0], v[1], arr[(i + 1 + arr.length) % arr.length][0], arr[(i + 1 + arr.length) % arr.length][1]), t)]).pop();

const segments = [
    corePositions.map((v, i, arr) => [v, sub2(arr[(i + 1)%arr.length], v), scale2(norm2(sub2(arr[(i + 1)%arr.length], v)), width)]),
    trianglePositions.map((v, i, arr) => [v, sub2(arr[(i + 1)%arr.length], v), scale2(norm2(sub2(arr[(i + 1)%arr.length], v)), width)])
].flatMap(sc => [[2, -2].map(r => rot2(Math.PI / r)).map(r => sc.map(i => [add2(i[0], trans2(r, i[2])), i[1]]).map(connectIntersections))].flatMap(cs => cs[0].map((v, i) => [v, cs[1][i]])));
const shortShadow = Array.from({length:8}).map((v, i) => i).filter(i => i != 2 && i != 5);

const getPts = (r, l, fr, tr) => [add2(r[0], scale2(r[1], fr)), add2(r[0], scale2(r[1], tr)), add2(l[0], scale2(l[1], tr)), add2(l[0], scale2(l[1], fr))];

function walk(i) {
    const run = i / segments.length | 0;
    const idx = i%segments.length;

    const ptss = [];
    let shadowPts = null;
    if(run == 0) {
        ptss.push([getPts(segments[idx][0], segments[idx][1], 0, .5), 0]);
        ptss.push([getPts(segments[idx][0], segments[idx][1], shortShadow.includes(i % segments.length)? .01: .08, .4), 1]);
    } else if(run == 1) {
        ptss.push([getPts(segments[idx][0], segments[idx][1], .5, 1), 0]);
    } else if(run == 2) {
        ptss.push([getPts(segments[idx][0], segments[idx][1], 0, shortShadow.includes(i % segments.length)? .01: .08), 1]);
        ptss.push([getPts(segments[idx][0], segments[idx][1], .4, 1), 1]);
    }

    ptss.forEach(pts => {
        const p = polygons.create();
        p.addPoints(...(pts[1] == 0? pts[0]: pts[0].map(pt => add2(pt, [3, 2]))));
        pts[1] == 0? p.addSegments(...pts[0]): p.addHatching(.5,.7);
        polygons.draw(turtle, p, pts[1] == 0);
    });

    return i < segments.length * 3 - 1;
}

function norm2(a) { return scale2(a, 1/len2(a)); }
function add2(a, b) { return [a[0]+b[0], a[1]+b[1]]; }
function sub2(a, b) { return [a[0]-b[0], a[1]-b[1]]; }
function mul2(a, b) { return [a[0]*b[0], a[1]*b[1]]; }
function scale2(a, s) { return mul2(a, [s,s]); }
function lerp2(a,b,t) { return [a[0]*(1-t) + b[0]*t, a[1]*(1-t) + b[1]*t]; }
function lenSq2(a) { return a[0]**2+a[1]**2; }
function len2(a) { return Math.sqrt(lenSq2(a)); }
function rot2(a) { return [Math.cos(a), -Math.sin(a), Math.sin(a), Math.cos(a)]; }
function trans2(m, a) { return [m[0]*a[0]+m[2]*a[1], m[1]*a[0]+m[3]*a[1]]; }
function dist2(a,b) { return Math.hypot(...sub2(a,b)); }
function dot2(a,b) { return a[0]*b[0]+a[1]*b[1]; }
function cross2(a,b) { return a[0]*b[1] - a[1]*b[0]; }
function multiply2(a2x2, a) { return [(a[0]*a2x2[0])+(a[1]*a2x2[1]),(a[0]*a2x2[2])+(a[1]*a2x2[3])]; }
function intersect_info2(as, ad, bs, bd) {
    const d = [bs[0] - as[0], bs[1] - as[1]];
    const det = bd[0] * ad[1] - bd[1] * ad[0];
    if(det === 0) return false;
    const res = [(d[1] * bd[0] - d[0] * bd[1]) / det, (d[1] * ad[0] - d[0] * ad[1]) / det];
    return [...res, add2(as, scale2(ad, res[0]))];
}
function intersect_ray2(a, b, c, d) {
    const i = intersect_info2(a, b, c, d);
    return i === false? i: i[2];
}
function segment_intersect2(a,b,c,d, inclusive = true) {
    const i = intersect_info2(a, sub2(b, a), c, sub2(d, c));
    if(i === false) return false;
    const t = inclusive? 0<=i[0]&&i[0]<=c&&0<=i[1]&&i[1]<=1: 0<i[0]&&i[0]<1&&0<i[1]&&i[1]<1;
    return t?i[2]:false;
}
function eq2(a,b) { return a[0]==b[0]&&a[1]==b[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)}}}