// Path repulsion. Created by Jurgen Westerhof 2024

const seed = 'Empty seed is random every run.'; //type=string
const size = 90; //min=10 max=100 step=1
const population = 1; //min=0 max=4 step=.01 Multiplier of walker population per area
const pencils = 1; //min=1 max=10 step=1 The number of different colored pensils to use in a plot. Be sure to supply the same seed for different channels.
const drawPencil = 1; //min=1 max=10 step=1 The color to plot. Be sure to supply the same seed for different pencils.
const repulsion = 1; //min=1 max=2 step=.01

const config = {
    populationMultiplier: population**2,
    channels: pencils,
    drawChannel: Math.min(drawPencil, pencils),
    size: size,
    repulsion: repulsion,
};

// Seedable random number generator by David Bau: http://davidbau.com/archives/2010/01/30/random_seeds_coded_hints_and_quintillions.html
!function(a,b,c,d,e,f,g,h,i){function j(a){var b,c=a.length,e=this,f=0,g=e.i=e.j=0,h=e.S=[];for(c||(a=[c++]);d>f;)h[f]=f++;for(f=0;d>f;f++)h[f]=h[g=s&g+a[f%c]+(b=h[f])],h[g]=b;(e.g=function(a){for(var b,c=0,f=e.i,g=e.j,h=e.S;a--;)b=h[f=s&f+1],c=c*d+h[s&(h[f]=h[g=s&g+b])+(h[g]=b)];return e.i=f,e.j=g,c})(d)}function k(a,b){var c,d=[],e=typeof a;if(b&&"object"==e)for(c in a)try{d.push(k(a[c],b-1))}catch(f){}return d.length?d:"string"==e?a:a+"\0"}function l(a,b){for(var c,d=a+"",e=0;e<d.length;)b[s&e]=s&(c^=19*b[s&e])+d.charCodeAt(e++);return n(b)}function m(c){try{return o?n(o.randomBytes(d)):(a.crypto.getRandomValues(c=new Uint8Array(d)),n(c))}catch(e){return[+new Date,a,(c=a.navigator)&&c.plugins,a.screen,n(b)]}}function n(a){return String.fromCharCode.apply(0,a)}var o,p=c.pow(d,e),q=c.pow(2,f),r=2*q,s=d-1,t=c["seed"+i]=function(a,f,g){var h=[];f=1==f?{entropy:!0}:f||{};var o=l(k(f.entropy?[a,n(b)]:null==a?m():a,3),h),s=new j(h);return l(n(s.S),b),(f.pass||g||function(a,b,d){return d?(c[i]=a,b):a})(function(){for(var a=s.g(e),b=p,c=0;q>a;)a=(a+c)*d,b*=d,c=s.g(1);for(;a>=r;)a/=2,b/=2,c>>>=1;return(a+c)/b},o,"global"in f?f.global:this==c)};if(l(c[i](),b),g&&g.exports){g.exports=t;try{o=require("crypto")}catch(u){}}else h&&h.amd&&h(function(){return t})}(this,[],Math,256,6,52,"object"==typeof module&&module,"function"==typeof define&&define,"random");
Math.seedrandom(seed == ''? (new Date().getTime()): seed);

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

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

const proximityThreshold = 3;

const MODE_INACTIVE = 0;
const MODE_NORMAL = 1;
const MODE_REVERSE = 2;

class Walker {
    constructor(turtle, position, direction, maxTurn = Math.PI * 2, turnResolution = Math.PI / 360) {
        this.t = turtle;
        this.p = position;
        this.d = direction;
        this.mt = maxTurn;
        this.tr = turnResolution;
        this.mode = MODE_NORMAL;
        this.startPosition = position.map(v => v);
        this.otherDirection = V.scale(direction, -1);
        
        this.turnPreference = Math.random() < .5? 1: -1;
        this.channel = (config.channels * Math.random() | 0) + 1;
    }
    step(scene) {
        if(this.mode === MODE_INACTIVE) return;
        this.t.jump(this.p);
        
        function tryCandidates(p, d, maxTurn, turnResolution, tp) {
            for(let sign = 1; sign >= -1; sign-=2) {
                for(let t = 0; t <= maxTurn; t += turnResolution) {
                    const rotatedD = V.trans(V.rot2d(tp*sign*t), d);
                    const candidateP = V.add(p, rotatedD);
                    if(!scene.proximityToRegistered(candidateP, p, config.repulsion)) {
                        return [candidateP, rotatedD];
                    }
                }
            }
            return false;
        }
        const candidateP_RotatedD = tryCandidates(this.p, this.d, this.mt, this.tr, this.turnPreference);
        
        if(candidateP_RotatedD === false) {
            if(this.mode == MODE_REVERSE) {
                this.mode = 0;
                return;
            }
            this.p = this.startPosition;
            this.d = this.otherDirection;
            this.mode = MODE_REVERSE;
            return this.step(scene);
        }
        this.p = candidateP_RotatedD[0];
        this.d = candidateP_RotatedD[1];
        if(this.channel == config.drawChannel) this.t.goto(this.p);
        scene.registerPoint(this.p);
    }
}

class WalkerScene {
    constructor(s, binSize = 2) {
        this.walkers = [];
        this.s = s;
        this.binSize = binSize;
        this.bins = [];
        for(let x = -120; x <= 120; x++) {
            const xBin = (x/binSize)|0;
            if(this.bins[xBin] == undefined) this.bins[xBin] = [];
            for(let y = -120; y <= 120; y++) {
                const yBin = (y/binSize)|0;
                if(this.bins[xBin][yBin] == undefined) this.bins[xBin][yBin] = [];
            }
        }
    }
    addWalker(walker) {
        this.walkers.push(walker);
        this.registerPoint(walker.p);
    }
    registerPoint(point) {
        const xBin = (point[0] / this.binSize) | 0;
        const yBin = (point[1] / this.binSize) | 0;
        this.bins[xBin - 1][yBin - 1].push(point.map(v => v));
        this.bins[xBin - 1][yBin    ].push(point.map(v => v));
        this.bins[xBin - 1][yBin + 1].push(point.map(v => v));
        this.bins[xBin    ][yBin - 1].push(point.map(v => v));
        this.bins[xBin    ][yBin    ].push(point.map(v => v));
        this.bins[xBin    ][yBin + 1].push(point.map(v => v));
        this.bins[xBin + 1][yBin - 1].push(point.map(v => v));
        this.bins[xBin + 1][yBin    ].push(point.map(v => v));
        this.bins[xBin + 1][yBin + 1].push(point.map(v => v));
    }
    proximityToRegistered(p, excluding, threshold = 1) {
        if(p[0] < -this.s || p[0] > this.s || p[1] < -this.s || p[1] > this.s) return true;
        const thresholdSq = threshold**2;

        const xBin = (p[0] / this.binSize) | 0;
        const yBin = (p[1] / this.binSize) | 0;

        for(let i = 0; i < this.bins[xBin][yBin].length; i++) {
            if(V.equals(this.bins[xBin][yBin][i], excluding)) continue;
            if(V.lenSq(V.sub(this.bins[xBin][yBin][i], p)) < thresholdSq) return true;
        }
        return false;
    }
    step() {
        this.walkers.forEach(walker => walker.step(this));
    }
    hasActive() {
        return this.walkers.some(w => w.mode !== MODE_INACTIVE);
    }
}
const ws = new WalkerScene(config.size);
for(let i = 0; i < config.populationMultiplier * config.size**2 / 10; i++) {
//    const newPt = [Math.random() * s * 2 - s, Math.random() * s * 2 - s];
//    ws.addWalker(new Walker(turtle, newPt, V.scale(V.norm(newPt), V.len(newPt) > 50?1: -1)));

    ws.addWalker(
        new Walker(
            turtle,
            [Math.random() * config.size * 2 - config.size, Math.random() * config.size * 2 - config.size],
            V.scale(V.norm([Math.random()-.5, Math.random()-.5]), 1)
        )
    );
}

// The walk function will be called until it returns false.
function walk(i) {
    ws.step();
    //for(let j = 0; j < 40000000; j++) {}
    return ws.hasActive();
}


function 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 equals(a,b)   { return !a.some((e, i) => e != b[i]); }
        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;}
        static tour(tour, segmentStart, segmentDirection) { return tour.map((e, i, a) => [i, this.info(e, V.sub(a[(i+1)%a.length], e), segmentStart, segmentDirection)]).filter(e => e[1] !== false && 0 <= e[1][1] && e[1][1] <= 1).filter(e => 0 <= e[1][2]).map(e => ({position: e[1][0],tourIndex: e[0],tourSegmentPortion: e[1][1],segmentPortion: e[1][2],}));}
        static inside(tour, pt) { return tour.map((e,i,a) => this.segment(e, a[(i+1)%a.length], pt, [Number.MAX_SAFE_INTEGER, 0], true, false)).filter(e => e !== false).length % 2 == 1; }
        static circles(centerA, radiusA, centerB, radiusB) {const result = {intersect_count: 0,intersect_occurs: true,one_is_in_other: false,are_equal: false,point_1: [null, null],point_2: [null, null],};const dx = centerB[0] - centerA[0];const dy = centerB[1] - centerA[1];const dist = Math.hypot(dy, dx);if (dist > radiusA + radiusB) {result.intersect_occurs = false;}if (dist < Math.abs(radiusA - radiusB) && !N.approx(dist, Math.abs(radiusA - radiusB))) {result.intersect_occurs = false;result.one_is_in_other = true;}if (V.approx(centerA, centerB) && radiusA === radiusB) {result.are_equal = true;}if (result.intersect_occurs) {const centroid = (radiusA**2 - radiusB**2 + dist * dist) / (2.0 * dist);const x2 = centerA[0] + (dx * centroid) / dist;const y2 = centerA[1] + (dy * centroid) / dist;const prec = 10000;const h = (Math.round(radiusA**2 * prec)/prec - Math.round(centroid**2 * prec)/prec)**.5;const rx = -dy * (h / dist);const ry = dx * (h / dist);result.point_1 = [x2 + rx, y2 + ry];result.point_2 = [x2 - rx, y2 - ry];if (result.are_equal) {result.intersect_count = null;} else if (result.point_1.x === result.point_2.x && result.point_1.y === result.point_2.y) {result.intersect_count = 1;} else {result.intersect_count = 2;}}return result;}
    }
    this.Intersection = Intersection2D;
    
    class PathTools {
        static bezier(p1, cp1, cp2, p2, steps = null) {steps = (steps === null? (V.len(V.sub(cp1, p1)) + V.len(V.sub(cp2, cp1)) + V.len(V.sub(p2, cp2))) | 0: steps) - 1;return Array.from({length: steps + 1}).map((v, i, a, f = i/steps) => [[V.lerp(p1, cp1, f),V.lerp(cp1, cp2, f),V.lerp(cp2, p2, f)]].map(v => V.lerp(V.lerp(v[0], v[1], f), V.lerp(v[1], v[2], f), f))[0]);}
        // https://stackoverflow.com/questions/18655135/divide-bezier-curve-into-two-equal-halves#18681336
        static splitBezier(p1, cp1, cp2, p2, t=.5) {const e = V.lerp(p1, cp1, t);const f = V.lerp(cp1, cp2, t);const g = V.lerp(cp2, p2, t);const h = V.lerp(e, f, t);const j = V.lerp(f, g, t);const k = V.lerp(h, j, t);return [[p1, e, h, k], [k, j, g, p2]];}
        static circular(radius,verticeCount,rotation=0) {return Array.from({length: verticeCount}).map((e,i,a,f=i*2*Math.PI/verticeCount+rotation) => [radius*Math.cos(f),radius*Math.sin(f)])}
        static circle(r){return this.circular(r,Math.max(12, r*2*Math.PI|0));}
        static arc(radius, extend = 2 * Math.PI, clockWiseStart = 0, steps = null, includeLast = false) { return [steps == null? (radius*extend+1)|0: steps].map(steps => Array.from({length: steps}).map((v, i, a) => [radius * Math.cos(clockWiseStart + extend*i/(a.length-(includeLast?1:0))), radius * Math.sin(clockWiseStart + extend*i/(a.length-(includeLast?1:0)))])).pop(); }
        static draw(turtle, path) {path.forEach((pt, i) => turtle[i==0?'jump':'goto'](pt));}
        static drawTour(turtle, path) {this.draw(turtle, path.concat([path[0]]));}
        static drawPoint(turtle, pt, r = .1) {this.drawTour(turtle, this.circle(r).map(e => V.add(e, pt)));}
        static drawArrow(turtle, s, d, width = 6, length = 3) {turtle.jump(s);const arrowHeadBase = V.add(s,d);turtle.goto(arrowHeadBase);turtle.goto(V.add(arrowHeadBase, V.trans(V.rot2d(-V.angle(d)), [-length, width/2])));turtle.jump(V.add(arrowHeadBase, V.trans(V.rot2d(-V.angle(d)), [-length, -width/2])));turtle.goto(arrowHeadBase);}
        static circlesTangents(c1_center, c1_radius, c2_center, c2_radius, internal = false) {let middle_circle = [V.scale(V.sub(c1_center, c2_center), .5)].map(hwp => [V.add(c2_center, hwp), V.len(hwp)]).pop();if(!internal && c1_radius == c2_radius) {let target = V.sub(c2_center, c1_center);let scaledTarget = V.scale(target, c1_radius/V.len(target));let partResult = [V.add(c1_center, V.trans(V.rot2d(Math.PI/2), scaledTarget)),V.add(c1_center, V.trans(V.rot2d(Math.PI/-2), scaledTarget))];return [partResult,partResult.map(pt => V.add(pt, target))]}let swap = !internal && c2_radius > c1_radius;if(swap) {let t = [[...c1_center], c1_radius];c1_center = c2_center;c1_radius = c2_radius;c2_center = t[0];c2_radius = t[1];}let internal_waypoints = intersectCircles2(c1_center, c1_radius + (internal?c2_radius:-c2_radius), ...middle_circle);if(internal_waypoints.length == 0) return [];const circlePointAtDirection2 = (circle_center, radius, direction) => V.add(circle_center, V.scale(direction, radius/V.len(direction)));const result = [[circlePointAtDirection2(c1_center, c1_radius, V.sub(internal_waypoints[0], c1_center)),circlePointAtDirection2(c1_center, c1_radius, V.sub(internal_waypoints[1], c1_center))],[circlePointAtDirection2(c2_center, c2_radius, internal? V.sub(c1_center, internal_waypoints[0]): V.sub(internal_waypoints[0], c1_center)),circlePointAtDirection2(c2_center, c2_radius, internal? V.sub(c1_center, internal_waypoints[1]): V.sub(internal_waypoints[1], c1_center))]];return swap? [[result[1][1],result[1][0]],[result[0][1],result[0][0]]]: result;}
    }

    this.PT = PathTools;
    
    class Complex {
        static add(a,b)     { return V.add(a,b); }
        static sub(a,b)     { return V.sub(a,b); }
        static scale(a,s)   { return V.scale(a,s); }
        static mult(a,b)    { return [a[0]*b[0]-a[1]*b[1],a[0]*b[1]+a[1]*b[0]]; }
        static sqrt(a)      { return [[Math.hypot(...a)**.5, Math.atan2(...a.reverse()) / 2]].map(ra => [ra[0]*Math.cos(ra[1]), ra[0]*Math.sin(ra[1])]).pop(); }
    }
    this.C = Complex;
    
    class Numbers {
        static approx(a,b,p)        { return Math.abs(a-b) < (p === undefined? .001: p); }
        static clamp(a, min, max)   { return Math.min(Math.max(a, min), max); }
    }
    this.N = Numbers;
    
    class Matrix {
        static bayer(order) { return [...Array(1<<order)].map((_,y,a) => { const g = (k=order,x)=>k--&&4*g(k,x)|2*(x>>k)+3*(y>>k&1)&3; return a.map(g); }); }
        static rotate(m) { return m[0].map((e, i) => m.map(r => r[i]).reverse()); }
        static rotateCCW(m) { return m[0].map((e, i) => m.map(r => r[r.length-1-i])); }
        static add(a,b) { return a.map((e, c) => e.map((e, r) => a[c][r] + b[c][r])); }
        static sub(a,b) { return a.map((e, c) => e.map((e, r) => a[c][r] - b[c][r])); }
        static multiply(a,b) { return Array.from({length: b.length}, (e,resCol) => Array.from({length: a[0].length}, (e,resRow) => b[resCol].reduce((acc, c, bRow) => acc + a[bRow][resRow] * b[resCol][bRow], 0)));}
        static scale(a,s) { return a.map((e, c) => e.map((e, r) => a[c][r] * s)); }
        static random(c,r,fillFn = Math.random) { return Array.from({length: c}, (e,i) => Array.from({length: r}, e => fillFn(c, r))); }
        static identity(d) { return Array.from({length: d}, (e,c) => Array.from({length: d}, (e, r) => c==r?1:0 )); }
        static log(m, name, logFn = console.log) { if(name != undefined) logFn(name); if(m === undefined || (typeof m == 'object' && (m[0] === undefined || m[0][0] === undefined))) { return logFn(`Failed to log matrix:`, m); } logFn(m[0].map((e,r) => m.map((e,c) => m[c][r]).join(', ')).join('\n')); }
        static invert(m) { let _A = m.map(col => col.map(cell => cell));/*clone matrix*/let temp;const N = _A.length;const E = Array.from({length: N}, (e,i) => Array.from({length: _A[0].length}, (e,j) => i==j?1:0));for (let k = 0; k < N; k++) {temp = _A[k][k];for (let j = 0; j < N; j++) {_A[k][j] /= temp;E[k][j] /= temp;}for (let i = k + 1; i < N; i++) {temp = _A[i][k];for (let j = 0; j < N; j++) {_A[i][j] -= _A[k][j] * temp;E[i][j] -= E[k][j] * temp;}}}for (let k = N - 1; k > 0; k--) {for (let i = k - 1; i >= 0; i--) {temp = _A[i][k];for (let j = 0; j < N; j++) {_A[i][j] -= _A[k][j] * temp;E[i][j] -= E[k][j] * temp;}}}return E; }
        static determinant(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.determinant(m.slice(1).map(c => c.filter((_,j) => i != j))), 0)}
        static flip(m) { return Array.from({length: m[0].length}, (_, r) => Array.from({length: m.length}, (e, c) => m[c][r])); }
        static sum(m) { return m.reduce((a, c) => a + c.reduce((aa, cc) => aa + cc, 0), 0); }
    }
    this.M = Matrix;
    
    class Algorithms {
        static nthTriangular(n) { return ((n * n) + n) / 2; }
    }
    this.A = Algorithms;
}