// Forked from "More Multi-Scale Truchet Tiles" by Jurgen
// https://turtletoy.net/turtle/fa14c628d4

const splitProbability = .70; //min=0 max=1 step=.05
const startRes = 4; //min=0 max=5 step=1
const minRes = 1; //min=0 max=5 step=1
const bigTileSize = 80; //min=10 max=200 step=10

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

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

let width = bigTileSize;
let height = width / Math.sqrt(.75);

let columns = Math.ceil(200 / width);
let rows = Math.ceil(200 / height);

const hOffset = ((columns / 2) * width);
const vOffset = (rows / 2) * height;

const trns = (a, b) => [a[0] - hOffset, a[1] - vOffset];

let triangles = [];

// The walk function will be called until it returns false.
function walk(i) {
    let column = i % columns;
    let row = (i / columns)|0;
    let pointingLeft = (row % 2 == 0) === (column % 2 == 0);
    
    if((row * height / 2) - vOffset -height < 100) {
        generateTriangle(triangles, trns([(pointingLeft? column: column + 1) * width, row * height / 2]), pointingLeft? -Math.PI / 6: 5* Math.PI / 6, height, startRes);
        triangles.sort((a,b) => Math.random()-.5);
        return true;
    }
    
    let t = triangles.pop();
    t.draw(turtle);
    return triangles.length > 0;
}

function generateTriangle(triangles, position, heading, height, generation) {
    if(generation <= minRes || Math.random() > Math.pow(splitProbability, 1 + (startRes - generation))) {
        triangles.push(new Triangle(position, heading, height, generation));
    } else {
        generateTriangle(triangles, position, heading, height / 2, generation - 1);

        turtle.up();
        turtle.jump(position);
        turtle.seth(heading);
        turtle.forward(height / 2);
        generateTriangle(triangles, turtle.pos(), heading, height / 2, generation - 1);

        turtle.jump(position);
        turtle.seth(heading + (Math.PI/3));
        turtle.forward(height / 2);
        generateTriangle(triangles, turtle.pos(), heading, height / 2, generation - 1);

        turtle.jump(position);
        turtle.seth(heading + (Math.PI/6));
        turtle.forward(height * Math.sqrt(.75));
        turtle.seth(heading + Math.PI);
        generateTriangle(triangles, turtle.pos(), heading + Math.PI, height / 2, generation - 1);
    }
}

// vec2 helper functions
const add = (a, b) => [a[0]+b[0], a[1]+b[1]];
const sub = (a, b) => [a[0]-b[0], a[1]-b[1]];
const scl = (a, b) => [a[0]*b, a[1]*b];

class Triangle {
    constructor(position, heading, height, generation) {
        this.position = position;
        this.heading = heading;
        this.height = height;
        this.generation = generation;
        
        this.lanes = Math.pow(2, this.generation + 1);
        this.primaryCircles = generation == 0? 1: Math.ceil(this.lanes * .75);
    }
    draw(turtle) {
        const polygons = new Polygons();

        turtle.up();
        turtle.jump(this.position);
        turtle.seth(this.heading);
        let positions = [];
        for(let i = 0; i < 3; i++) {
            positions.push([turtle.pos(), (this.heading) + (i * 2 *  Math.PI / 3)]);
            turtle.forward(this.height);
            turtle.right(Math.PI/1.5);
        }
        turtle.down();
        
        positions.sort((a,b) => Math.random()-.5);

        let laneWidth = (this.height/this.lanes) / 2;

        let circles = [this.primaryCircles * 2, this.lanes, this.lanes];
        for(let k = 0; k < 3; k++) {
            let pos = positions[k];

            for(let i = 0; i <= circles[k]; i++) {
                let p = polygons.create();
                p.addPoints(pos[0]);
                this.addCirclePoints(p, pos[0], (i+.5) * laneWidth, pos[1], pos[1] + (Math.PI / 3), 0);
                if(i%2 == 1) {
                 //   p.addHatching(0, .15); //black
                } else {
                //   p.addHatching(0, 1); //white
                }
                // p.addOutline();
                polygons.draw(turtle, p);
            }
        }
    }
    addCirclePoints(p, position, r, s, e, rotation = 0) {
        const f = 40;
        for (let i=0; i<=f; i++) {
            p.addPoints(add([Math.cos(s+(e-s)*i/f)*r, Math.sin(s+(e-s)*i/f)*r], position));
            if (i < f)
            p.addSegments(
                add([Math.cos(s+(e-s)*(i)/f)*r, Math.sin(s+(e-s)*(i)/f)*r], position), 
                add([Math.cos(s+(e-s)*(i+1)/f)*r, Math.sin(s+(e-s)*(i+1)/f)*r], position));
        }
        return p;
    }
}

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