const paletteSize = 20;
// You can find the Turtle API reference here: https://turtletoy.net/syntax
Canvas.setpenopacity(-1/paletteSize);

// Global code will be evaluated once.

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

const len2 = (a) => Math.sqrt(lensq2(a));
const lensq2 = (a) => dot2(a, a);
const dot2 = (a, b) => a[0]*b[0]+a[1]*b[1];
const norm2 = (a) => { const l = len2(a); if(l < .00000001) throw new Exception("Normalizing 0-vector"); return scale2(a, 1/l); }
const add2 = (a, b) => [a[0]+b[0], a[1]+b[1]];
const sub2 = (a, b) => [a[0]-b[0], a[1]-b[1]];
const scale2 = (a, s) => [a[0]*s, a[1]*s];
const ortho2 = (a) => [-a[1], a[0]];

class Particle {
    constructor(args = {}) {
        const options = {...{position: [0, 0], radiusMin: 2, radiusMax: 4, activity: 1, fixed: null}, ...args};
        this.position = options.position;
        this.radius = options.radiusMin + Math.random() * (options.radiusMax-options.radiusMin);
        this.activity = options.activity;
        this.fixed = options.fixed;
        this.children = [];
        this.isMain = false;
    }
    move(base = [0, 0]) {
        let activityR = Math.random() * 2 * Math.PI;
        this.position = add2(this.position, add2(base, scale2([Math.cos(activityR), Math.sin(activityR)], this.activity * Math.random())));
    }
    draw(t) {
        t.jump(this.position[0], this.position[1] - this.radius);
        t.circle(this.radius);
        t.jump(this.position[0], this.position[1] - .075);
        t.circle(.075);
        if(this.fixed) {
            t.jump(this.position[0], this.position[1] - this.radius / 2);
            t.circle(this.radius / 2);
        }
    }
    drawTree(i = 0, width = 0) {
        if(this.fixed === null | this.fixed === true) return;

        const r = .075 + width * .075;
        
        const p = polygons.create();
        const direction = sub2(this.fixed.position, this.position);
        
        const angle = Math.atan2(...ortho2(direction)) + Math.PI * 1.5;
        
        const pts = [];
        let pt = this.position;
        
        const max = Math.max(r * 7, 10);
        for(let i = 0; i < max; i++) {
            pts.push(add2(pt, [
                r * -Math.cos(angle + Math.PI * i / max),
                r * Math.sin(angle + Math.PI * i / max),
            ]))
        }
        pt = add2(this.position, direction);
        for(let i = 0; i < max; i++) {
            pts.push(add2(pt, [
                r * Math.cos(angle + Math.PI * i / max),
                r * -Math.sin(angle + Math.PI * i / max),
            ]))
        }

        p.addPoints(...pts);
        p.addHatching(1, .15);

        polygons.draw(bales[i], p);
    }
}
const spawn = (options = {}) => new Particle({...
    {position: [
        200 * Math.random() - 100,
        180 * Math.random() - 80
    ]}, ...options}
);

let particles = Array.from({length: 50}).map(i => spawn());
let fixed = [spawn({position: [0, -100], fixed: true})];

let drawings = [];

// The walk function will be called until it returns false.
function walk(i) {
    if(drawings.length > 0) {
        let d = drawings.pop();
        d[0].drawTree(d[1], d[2]);
        return drawings.length > 0;
    }
    particles.forEach(p => p.move([0, -1]));
    let filtered = particles.filter(p => p.position[1] > -110);
    let count = particles.length - filtered.length;
    filtered.forEach(p => fixed.forEach(f => {
        if(f.position[0] - f.radius < p.position[0] + p.radius && f.position[0] + f.radius > p.position[0] - p.radius &&
           f.position[1] - f.radius < p.position[1] + p.radius && f.position[1] + f.radius > p.position[1] - p.radius) {
               p.fixed = f;
           }
    }));
    particles = filtered.filter(p => p.fixed === null);
    count += filtered.length - particles.length;
    filtered.filter(p => p.fixed !== null).forEach(p => fixed.push(p));
    Array.from({length: count}).forEach(p => particles.push(spawn({position: [200 * Math.random() - 100, 120]})))
    
    let lowest = fixed.filter(f => f.position[1] > 110);
    if(lowest.length > 0) {
        let lowest = fixed.filter(f => f.position[1] > 100);
        fixed.forEach(p => {
            if(p.fixed === true) return;
            p.fixed.children.push(p);
        });
        lowest.forEach(l => {
            while(l.fixed !== true) {
                l.isMain = true;
                l = l.fixed;
            }
        });
        
        [[0, 1], [1, 2], [4, 1], [10, 1], [13, 1], [15, 1], [16, 1], [17, 2], [18, 3], [19, 2]]
            .map(i => [(i[0] * paletteSize / 20) | 0, i[1]])
            .map((i, idx, all) => [i[0], all.filter((q, qi) => qi < idx).reduce((p, c) => p+c[1], 0)])
            .forEach(i => 
                fixed.filter(f => f.isMain && f.fixed !== true).forEach(o => drawings.push([o, i[0], i[1] * 5]))
            );

        [[0, 1], [13, 2], [15, 4], [18, 5], [19, 5]]
            .map(i => [(i[0] * paletteSize / 20) | 0, i[1]])
            .map((i, idx, all) => [i[0], all.filter((q, qi) => qi < idx).reduce((p, c) => p+c[1], 0)])
            .forEach(i => 
                fixed.filter(f => !f.isMain && f.fixed !== true).forEach(o => drawings.push([o, i[0], i[1] * 3]))
            );

        drawings = drawings.sort((a,b) => a[1] < b[1]? 1: a[1] > b[1]? -1: a[0].position[1] < b[0].position[1]? 1: -1);
    }
    return true;
}


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


////////////////////////////////////////////////////////////////
// Bale utility code - Created by Jurgen Westerhof 2022
// https://turtletoy.net/turtle/7269af8a23
// Abusing the opacity, usage:
//      Canvas.setpenopacity(1/baleSize);
//      const bales = Array.apply(null,{length: baleSize}).map(b => new Bale(baleSize--);
// Then use bales[x] wherever you would use a turtle object to 'draw'
// in 'color' x (i.e Polygon hatching with a bale object and .15 interspacing)
////////////////////////////////////////////////////////////////
function Bale(n) {
    class Bale {
        constructor(n) { this.turtles = Array.apply(null,{length: n}).map(i => new Turtle()); }
        
        back(e)         { this.turtles.map(t => t.back(e)); return this; }
        backward(e)     { this.turtles.map(t => t.backward(e)); return this; }
        bk(e)           { this.turtles.map(t => t.bk(e)); return this; }
        fd(e)           { this.turtles.map(t => t.fd(e)); return this; }
        forward(e)      { this.turtles.map(t => t.forward(e)); return this; }

        left(e)         { this.turtles.map(t => t.left(e)); return this; }
        lt(e)           { this.turtles.map(t => t.lt(e)); return this; }
        right(e)        { this.turtles.map(t => t.right(e)); return this; }
        rt(e)           { this.turtles.map(t => t.rt(e)); return this; }

        seth(e)         { this.turtles.map(t => t.seth(e)); return this; }
        setheading(e)   { this.turtles.map(t => t.setheading(e)); return this; }

        setx(e)         { this.turtles.map(t => t.setx(e)); return this; }
        sety(e)         { this.turtles.map(t => t.sety(e)); return this; }

        setpos(x, y)        { this.turtles.map(t => t.setpos(x, y)); return this; }
        setposition(x, y)   { this.turtles.map(t => t.setposition(x, y)); return this; }

        toradians(e)    { this.turtles.map(t => t.toradians(e)); return this; }
        degrees(e)      { this.turtles.map(t => t.degrees(e)); return this; }

        goto(x, y)      { this.turtles.map(t => t.goto(x, y)); return this; }
        jmp(x, y)       { this.turtles.map(t => t.jmp(x, y)); return this; }
        jump(x, y)      { this.turtles.map(t => t.jump(x, y)); return this; }

        circle(radius, extent, steps) { this.turtles.map(t => t.circle(radius, extent, steps)); return this; }

        clone()         { let b = new Bale(this.turtle.length); this.turtles.map((t, k) => b.turtles[k] = t.clone()); return b; }

        h()             { return this.turtles[0].h(); }
        heading()       { return this.turtles[0].heading(); }
        
        home()          { this.turtles.map(t => t.home()); return this; }
        
        isdown()        { return this.turtles[0].isdown(); }

        pos()           { return this.turtles[0].pos(); }
        position()      { return this.turtles[0].position(); }

        pd()            { this.turtles.map(t => t.pd()); return this; }
        pendown()       { this.turtles.map(t => t.pendown()); return this; }
        penup()         { this.turtles.map(t => t.penup()); return this; }
        pu()            { this.turtles.map(t => t.pu()); return this; }
        down()          { this.turtles.map(t => t.down()); return this; }
        up()            { this.turtles.map(t => t.up()); return this; }

        radians()       { this.turtles.map(t => t.radians()); return this; }

        x()             { return this.turtles[0].x(); }
        xcor()          { return this.turtles[0].xcor(); }
        y()             { return this.turtles[0].y(); }
        ycor()          { return this.turtles[0].ycor(); }
    }
    return new Bale(n);
}
function Bales(count, includeWhite = false) {
    if(count == 1) return [new Bale(1)];
    const getExponent = (base, target) => Math.log(target) / Math.log(base);
    const baleSize = count - (includeWhite?1:0);
    const n = Array.apply(null,{length: baleSize}).map((v,k) => Math.round(getExponent(1 - 1/count, 1 - (count - k == count?.99:(baleSize - k)/baleSize))));
    if(includeWhite) n.push(0);
    return n.map(i => new Bale(i));
}