const mode = 0; //min=0 max=1 step=1 (Polygon layers, Wire model)
const resolution = 2; //min=2 max=8 step=1 (Full, Triangles, Rectangles, Pentagons, Hexagons, Heptagons, Octagon)
const phase = 8; //min=1 max=10 step=1 (2π, π, 2π/3, π/2, 2π/5, π/3, 2π/7, π/4, 2π/9, π/5)
const phaseOffset = 2; //min=0 max=3.1 step=.1

// You can find the Turtle API reference here: https://turtletoy.net/syntax
Canvas.setpenopacity(mode == 1? -.8: -1);

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

const pi2 = Math.PI * 2;

const layers = 9;

const topWidth = 20;
const bottomWidth = 170;
const totalHeight = 180;
const height = totalHeight / layers;

const cameraPos = [0,-150,470];
const cameraLookAt = [0,20,0];
const viewProjectionMatrix = setupCamera(cameraPos, cameraLookAt);

const allLayers = [];

// The walk function will be called until it returns false.
function walk(layer) {
    if(layer <= layers + 4) {
        const width = topWidth + ((bottomWidth - topWidth) * layer / (layers - 1));
        const top = (totalHeight / -2 + layer * height - layer * 5) | 0;
        const bottom = (totalHeight / -2 + (layer + 1) * height) | 0;
        
        const precision = resolution == 2? width: resolution;
        
        const layerHeight = bottom - top;
        for(let y = 0; y < layerHeight; y++) {
            if(top + y > totalHeight / 2) { continue; }
            
            let pts = Array.from({length: precision}).map((p, idx) => {
                const cr =  (y/layerHeight) * (1 - Math.sin(pi2 * phase * idx/precision) / 7);
                return [
                    cr * Math.cos(pi2 * idx / precision + layer * phaseOffset),
                    top + y,
                    cr * Math.sin(pi2 * idx / precision + layer * phaseOffset)
                ];
            });
    
            pts = pts
                .map(p => multiply3(p, [width / 2, 1, width / 2])) // scale
                .map(p => transform4([...p,1], viewProjectionMatrix))
                .map(p => [p[0]/p[2] * 50, p[1] / p[2] * 50])
            ;
            
            allLayers.push(pts);
        }
        return true;
    }
    
    const drawPts = allLayers.shift();
    if(mode === 0) {
        const p = polygons.create();
        p.addPoints(...drawPts);
        p.addOutline();
        polygons.draw(turtle, p);
    } else {
        turtle.jump(drawPts[drawPts.length - 1]);
        drawPts.forEach(p => turtle.goto(p));
    }

    return allLayers.length > 0;
}

// Projection functions from https://turtletoy.net/turtle/b3acf08303 by Reinder
function setupCamera(camPos, camLookat) {
    const viewMatrix = lookAt4m(camPos, camLookat, [0,1,0]);
    const projectionMatrix = perspective4m(0.25, 1);
    return multiply4m(projectionMatrix, viewMatrix);
}

// vec3 functions
function scale3(a,b) { return [a[0]*b,a[1]*b,a[2]*b]; }
function multiply3(a,b) { return [a[0]*b[0],a[1]*b[1],a[2]*b[2]]; }
function len3(a) { return Math.sqrt(dot3(a,a)); }
function dist3(a,b) { return Math.sqrt((a[0]-b[0])**2+(a[1]-b[1])**2+(a[2]-b[2])**2); }
function normalize3(a) { return scale3(a,1/len3(a)); }
function add3(a,b) { return [a[0]+b[0],a[1]+b[1],a[2]+b[2]]; }
function sub3(a,b) { return [a[0]-b[0],a[1]-b[1],a[2]-b[2]]; }
function dot3(a,b) { return a[0]*b[0]+a[1]*b[1]+a[2]*b[2]; }
function cross3(a,b) { return [a[1]*b[2]-a[2]*b[1],a[2]*b[0]-a[0]*b[2],a[0]*b[1]-a[1]*b[0]]; }
// vec4 functions
function transform4(a,b) {
    const d=new Float32Array(4);
    for(let c=0;4>c;c++)d[c]=b[c]*a[0]+b[c+4]*a[1]+b[c+8]*a[2]+b[c+12];
    return d;
}
// mat4 functions
function lookAt4m(a,b,d) { // pos, lookAt, up
    const c=new Float32Array(16);
    b=normalize3(sub3(a,b));
    d=normalize3(cross3(d,b));
    const e=normalize3(cross3(b,d));
    c[0]=d[0];c[1]=e[0];c[2]=b[0];c[3]=0;
    c[4]=d[1];c[5]=e[1];c[6]=b[1];c[7]=0;
    c[8]=d[2];c[9]=e[2];c[10]=b[2];c[11]=0;
    c[12]=-(d[0]*a[0]+d[1]*a[1]+d[2]*a[2]);
    c[13]=-(e[0]*a[0]+e[1]*a[1]+e[2]*a[2]);
    c[14]=-(b[0]*a[0]+b[1]*a[1]+b[2]*a[2]);
    c[15]=1;
    return c;
}
function multiply4m(a,b) {
    const d=new Float32Array(16);
    for(let c=0;16>c;c+=4)
        for(let e=0;4>e;e++)
            d[c+e]=b[c+0]*a[0+e]+b[c+1]*a[4+e]+b[c+2]*a[8+e]+b[c+3]*a[12+e];
    return d;
}
function perspective4m(a,b) { // fovy, aspect
    const c=(new Float32Array(16)).fill(0,0);
    c[5]=1/Math.tan(a/2);
    c[0]=c[5]/b;
    c[10]=c[11]=-1;
    return c;
}


////////////////////////////////////////////////////////////////
// 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)}}}