### Kanizsa's triangle ðŸ‘€

```const size = 70; //min=20 max=87 step=1
const edges = 3; //min=3 max=9 step=1
const outline = 0; //min=0 max=1 step=1 (Connect, Opposite)
const penThickness = .15; //min=.05 max=2 step=.01

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

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

// The walk function will be called until it returns false.
function walk(i) {
const pts = circlePoints(size, 2 * Math.PI, Math.PI/6, edges * 2);

const trans = (pts) => pts.map(pt => add2(pt, [0, edges > 3?0:(-(3**.5 * size)/2**4) * 2 / (edges-1)]));

//invisible triangle
(() => {
const p = polygons.create();
p.addPoints(...trans(pts.filter((v, i) => i % 2 == 1)));
polygons.draw(turtle, p);
})();

//outlined triangle
(() => {
const thickMultiplier = outline == 0? 3/edges: edges/3;
pts.filter((v, i) => i % 2 == 0)
.map(pt => [scale2(pt, 1 - thickMultiplier*size/2800), scale2(pt, 1 + thickMultiplier*size/2800)])
.forEach((v, i, a) => {
const target = outline == 0? 1: (edges%2 == 1? Math.floor(edges/2): Math.floor(edges/2) - 1);
const p = polygons.create();
v[0],
v[1],
]));
polygons.draw(turtle, p);
})
})();

//circles at three points
(() => {
const circle = circlePoints(size/(edges+1));
pts.filter((v, i) => i % 2 == 1).forEach((pt, i) => {
const p = polygons.create();
polygons.draw(turtle, p);
})
})();

return false;
}

/// Below is the standard lib I just copy paste under almost all my turtles

function approx1(a,b,delta=0.0001) { return -delta < a-b && a-b < delta }

////////////////////////////////////////////////////////////////
// 2D Vector Math utility code - Created by several Turtletoy users
////////////////////////////////////////////////////////////////
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 [a[0]*s,a[1]*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]]; } //Matrix(2x1) x Matrix(2x2)
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])]; } //Matrix(2x2) x Matrix(1x2)
function intersect_info2(as, ad, bs, bd) {
const d = [bs[0] - as[0], bs[1] - as[1]];
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];
}
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]<=1&&0<=i[1]&&i[1]<=1: 0<i[0]&&i[0]<1&&0<i[1]&&i[1]<1;
return t?i[2]:false;
}
function approx2(a,b,delta=0.0001) { return len2(sub2(a,b)) < delta }
function eq2(a,b) { return a[0]==b[0]&&a[1]==b[1]; }
function clamp2(a, tl, br) { return [Math.max(Math.min(br[0], a[0]), tl[0]), Math.max(Math.min(br[1], a[1]), tl[1])]; }
function nearSq2(test, near, delta = .0001) {
return near[0] - delta < test[0] && test[0] < near[0] + delta &&
near[1] - delta < test[1] && test[1] < near[1] + delta;
}

////////////////////////////////////////////////////////////////
// Start of some path utility code - Created by Jurgen Westerhof 2023
////////////////////////////////////////////////////////////////
function circlePoints(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(); }
function pts2Edges(pts) { return pts.map((v, i, a) => [v, a[(i+1)%a.length]]); }
function drawPath(turtle, pts) { return pts.forEach((pt, i) => turtle[i == 0? 'jump':'goto'](pt)); }
function drawTour(turtle, pts) { return drawPath(turtle, pts.concat([pts[0]])); }
function drawPoint(turtle, pt) { return drawTour(turtle, circlePoints(.5).map(p => add2(p, pt))); }
function isInPolygon(edges, pt) { return edges.map(edge => intersect_info2(edge[0], sub2(edge[1], edge[0]), pt, [0, 300])).filter(ii => ii !== false && 0 <= ii[0] && ii[0] <= 1 && 0 < ii[1]).length % 2 == 1; }
function isInVectorTour(vectors, pt) { return vectors.map(v => intersect_info2(...v, pt[0], pt[1])).filter(ii => ii !== false && 0 <= ii[0] && ii[0] < 1 && 0 <= ii[1]).length % 2 == 1; }
function tourToVectors(path) { return path.map((v, i, a) => [v, sub2(a[(i+1)%a.length], v)]); }
function thickLinePaths(from, to, thickness) { return [trans2(rot2(Math.atan2(...sub2(to, from))), [thickness/2, 0])].map(v => [[add2(from, v), add2(to, v)], [sub2(from, v), sub2(to, v)]]).pop();}
function toursIntersect(path1, path2) { return path1.some((pt1, i1) => path2.some((pt2, i2) => segment_intersect2(pt1, path1[(i1 + 1) % path1.length], pt2, path2[(i2 + 1) % path2.length]) !== false)); }

// Fisher-Yates (aka Knuth) Shuffle
// https://stackoverflow.com/questions/2450954/how-to-randomize-shuffle-a-javascript-array#2450976
function shuffle(array) {
let currentIndex = array.length,  randomIndex;

// While there remain elements to shuffle.
while (currentIndex > 0) {

// Pick a remaining element.
randomIndex = Math.floor(Math.random() * currentIndex);
currentIndex--;

// And swap it with the current element.
[array[currentIndex], array[randomIndex]] = [
array[randomIndex], array[currentIndex]];
}

return array;
}

////////////////////////////////////////////////////////////////
// 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)}}}
```