### Smack! ðŸª¼

Ever wonder what a group of jellyfish is called?

Concept: reddit.com/r/generat…and_polygon_packing/

```const turbulence = .2; //min=0 max=1 step=.1
const spawnOffset = 80; //min=25 max=150 step=1
const jellyfishCount = 12; //min=1 max=30 step=1
const jellyMarginTop = 2; //min=0 max=20 step=1
const jellyMarginSide = 4; //min=0 max=10 step=.5
const jellyInitMin = 5; //min=5 max=50 step=.5
const jellyInitMax = 35; //min=5 max=50 step=.5
const minTrailMargin = 4; //min=0 max=10 step=.5
const trailInterMargin = 3; //min=0 max=10 step=.5
const trailSpeckRadius = .7; //min=.1 max=3 step=.1
const hatch = 1; //min=0 max=1 step=1 (No, Yes)

const directionZoom = .0001 + .0049 * turbulence;
const jellyMin = Math.min(jellyInitMin, jellyInitMax);
const jellyMax = Math.max(jellyInitMin, jellyInitMax);

// You can find the Turtle API reference here: https://turtletoy.net/syntax
Canvas.setpenopacity(.7);

// Global code will be evaluated once.
const turtle = new Turtle(); turtle.radians();
const polygons = new Polygons();
const directionNoise = new SimplexNoise((Math.random() * 100) | 0);

const offset = spawnOffset;
const directionOffset = Math.random();

const upd = new UniformPointDistributor([-offset, -offset], [offset, offset]).getPointIterator();

const jellyfishes = [];
const jellytrails = [];

const trailPointsDrawn = [];

// The walk function will be called until it returns false.
function walk(i) {
const phase = (i / jellyfishCount) | 0;
i = i % jellyfishCount;

function getJellyfishPath(pt, dir, r) {
return circlePoints(r, Math.PI, 0, null, true).map(p => add2(pt, trans2(rot2(dir + Math.PI/2), p)));
}

switch(phase) {
case 0: // generate jellyfishes
const pt = upd.next().value.filter((v, i) => i < 2);

const r = jellyMin + (Math.random() * (jellyMax - jellyMin));

jellyfishes.push({
pt: pt,
r: r,
dir: dir,
normal: trans2(rot2(dir + Math.PI/2), [0,1]),
i: jellyfishes.length,
path: getJellyfishPath(pt, dir, r + jellyMarginTop)
});

break;
case 1: // avoid clipping and draw bodies
if(i > 0) return true;

function populateClips(jf) {
jf.clips = jellyfishes.filter(cf =>
cf.i != jf.i //not the same jf
&&
lenSq2(sub2(jf.pt, cf.pt)) < (jf.r + cf.r + jellyMarginTop)**2 // the distance of centers is smaller than radii + margin
&&
toursIntersect(jf.path, cf.path)
)
}
jellyfishes.forEach(jf => populateClips(jf));

let th = 50;
while(jellyfishes.some(jf => jf.clips.length > 0 && jf.r > 0) && th > 0) {
jellyfishes.filter(jf => jf.clips.length > 0).forEach(jf => {
jf.r = Math.max(jf.r - jellyMarginTop, 2 * jellyMarginSide);
jf.path = getJellyfishPath(jf.pt, jf.dir, jf.r + jellyMarginTop);
})
jellyfishes.forEach(jf => populateClips(jf));
th--;
}

jellyfishes.forEach(jf => {
jf.path = getJellyfishPath(jf.pt, jf.dir, jf.r);

const p = polygons.create();
if(hatch == 1) {
}
polygons.draw(turtle, p);
});

break;
case 2: // generate tentacles (trails)
const gf = jellyfishes[i].path;

drawTour(turtle, gf);

const mid = sub2(gf[gf.length - 1], gf[0]);
const d = norm2(mid);

const ks = [];
const dst_inc = () => minTrailMargin + Math.random() * 5;
let dst = 0;
while(dst < jellyfishes[i].r - jellyMarginSide) {
ks.unshift(-dst);
dst += dst_inc();
}
ks.pop();
dst = 0;
while(dst < jellyfishes[i].r - jellyMarginSide) {
ks.push(dst);
dst += dst_inc();
}
const sks = shuffle(ks)

const trails = [];
for(k in sks) {
let p = add2([...jellyfishes[i].pt], scale2(d, sks[k]));
const trail = [];
for(let j = 0; j < 60; j++) {
trail.push(p);
}
trails.push(trail);
}
jellytrails.push(trails);
break;
case 3: // draw trails
jellytrails[i].forEach(trail => {
for(let j = 0; j < trail.length; j++) {
if(jellyfishes
.filter((jf, ii) => ii != i)
.filter(jf => lenSq2(sub2(trail[j], jf.pt)) < (jf.r + jellyMarginTop) ** 2)
.some(jf => dot2(norm2(sub2(trail[j], jf.pt)), jf.normal) > -.2)) break;

if(trailPointsDrawn.filter(p =>
trail[j][0] - trailInterMargin < p[0] && p[0] < trail[j][0] + trailInterMargin &&
trail[j][1] - trailInterMargin < p[1] && p[1] < trail[j][1] + trailInterMargin
).some(p => lenSq2(sub2(trail[j], p)) < trailInterMargin**2)) break;

trailPointsDrawn.push(trail[j]);

const p = polygons.create();
if(hatch == 1) {
}
polygons.draw(turtle, p);
}
})
break;
default:
return false
}
return true;
}

return (directionNoise.noise2D(scale2(pt, directionZoom)) + directionOffset) * Math.PI;
}

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) =>
{
//        console.log('i', segment_intersect2(pt1, path1[(i1 + 1) % path1.length], pt2, path2[(i2 + 1) % path2.length]));
return 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;
}

////////////////////////////////////////////////////////////////
// Simplex Noise utility code. Created by Reinder Nijhoff 2020
// https://turtletoy.net/turtle/6e4e06d42e
// Based on: http://webstaff.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
////////////////////////////////////////////////////////////////
function SimplexNoise(seed = 1) {const grad = [  [1, 1, 0], [-1, 1, 0], [1, -1, 0], [-1, -1, 0],[1, 0, 1], [-1, 0, 1], [1, 0, -1], [-1, 0, -1],[0, 1, 1], [0, -1, 1], [0, 1, -1], [0, -1, -1] ];const perm = new Uint8Array(512);const F2 = (Math.sqrt(3) - 1) / 2, F3 = 1/3;const G2 = (3 - Math.sqrt(3)) / 6, G3 = 1/6;const dot2 = (a, b) => a[0] * b[0] + a[1] * b[1];const sub2 = (a, b) => [a[0] - b[0], a[1] - b[1]];const dot3 = (a, b) => a[0] * b[0] + a[1] * b[1] + a[2] * b[2];const sub3 = (a, b) => [a[0] - b[0], a[1] - b[1], a[2] - b[2]];class SimplexNoise {constructor(seed = 1) {for (let i = 0; i < 512; i++) {perm[i] = i & 255;}for (let i = 0; i < 255; i++) {const r = (seed = this.hash(i+seed)) % (256 - i)  + i;const swp = perm[i];perm[i + 256] = perm[i] = perm[r];perm[r + 256] = perm[r] = swp;}}noise2D(p) {const s = dot2(p, [F2, F2]);const c = [Math.floor(p[0] + s), Math.floor(p[1] + s)];const i = c[0] & 255, j = c[1] & 255;const t = dot2(c, [G2, G2]);const p0 = sub2(p, sub2(c, [t, t]));const o  = p0[0] > p0[1] ? [1, 0] : [0, 1];const p1 = sub2(sub2(p0, o), [-G2, -G2]);const p2 = sub2(p0, [1-2*G2, 1-2*G2]);let n =  Math.max(0, 0.5-dot2(p0, p0))**4 * dot2(grad[perm[i+perm[j]] % 12], p0);n += Math.max(0, 0.5-dot2(p1, p1))**4 * dot2(grad[perm[i+o[0]+perm[j+o[1]]] % 12], p1);n += Math.max(0, 0.5-dot2(p2, p2))**4 * dot2(grad[perm[i+1+perm[j+1]] % 12], p2);return 70 * n;}hash(i) {i = 1103515245 * ((i >> 1) ^ i);const h32 = 1103515245 * (i ^ (i>>3));return h32 ^ (h32 >> 16);}}return new SimplexNoise(seed);}

////////////////////////////////////////////////////////////////
// Uniform Point Distribution code - Created by Jurgen Westerhof 2023
////////////////////////////////////////////////////////////////
function UniformPointDistributor(leftTop = [-100, -100], rightBottom = [100, 100]) {
class UniformPointDistributor {
constructor(leftTop = [-100, -100], rightBottom = [100, 100]) {
this.leftTop = leftTop;
this.rightBottom = rightBottom;
this.width = rightBottom[0]-leftTop[0];
this.height = rightBottom[1]-leftTop[1];
this.maxDist = (this.width**2+this.height**2)**.5;
this.pts = [];
}

*getPointIterator(radiusFunction = null, candidates = 20, maxTries = 1000) {

const randomPoint = () => [Math.random()*this.width+this.leftTop[0],Math.random()*this.height+this.leftTop[1]];

yield this.pts[this.pts.length - 1];

while(true) {
let pt = [0,0,-1];
let tries = 0;
while(pt[2] < 0 && tries < maxTries) {
tries++;
//using [length] candidate points
pt = Array.from({length: candidates})
//which are random points
.map(i => randomPoint())
//then add the distance to that candidate minus the radius of each point it is compared to
.map(i => [i[0], i[1], this.pts.map(j => [j[0], j[1], Math.hypot(i[0]-j[0], i[1]-j[1]) - j[2]])
//so that it is the smallest distance from the
//candidate to any of the already chosen points
.reduce((prev, current) => (current[2] < prev[2])? current: prev, [0,0,this.maxDist])[2]
])
//then pick the candidate that has the largest minimum distance from the group of candidates
.reduce((prev, current) => prev == null? current: ((current[2] > prev[2])? current: prev), null)
//and set the 3rd position to its own radius instead of the distance to the nearest point
.map((v, i, arr) => i < 2? v: radiusFunction(arr[0], arr[1], v))
////and remove the distance before promoting the candidate
//.filter((i, k) => k < 2)
}
if(tries == maxTries) return false;
//add a point to the list
this.pts.push(pt);
yield pt;
}
}
}
return new UniformPointDistributor(leftTop, rightBottom);
}

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