### Layered diamonds ðŸ’

Grid of layered diamonds

```Canvas.setpenopacity(0.85);

const turtle = new Turtle();
const polygons = new Polygons();
const gridType = 2; // min=1, max=6, step=1
const grid = 9; // min=5, max=35, step=2
const scale = 175 / grid;

const diamondWidth = 75; // min=5, max=100, step=1
const diamondHeight = 50; // min=5, max=100, step=1

const sizeX = diamondWidth / grid;
const sizeY = diamondHeight / grid;

const layers = 6; // min=1, max=40, step=1
const layerDistance = 0.5; // min=0.1, max=1.75, step=0.001

const hatchType = 1; // min=0, max=4, step=1
const minHatching = 1.0;
const maxHatching = 0.275;
const useOutline = 1; // min=0, max=1, step=1

// The walk function will be called until it returns false.
function walk(i) {
let gridX = (i % grid) - (grid/2|0);
let gridY = grid - (i/grid|0) - (grid/2|0);
gridY -= 0.5;
if (gridX % 2 == 0) {
} else {
gridY -= 0.5;
}
const x = gridX * scale;
const y = gridY * scale;

let totalLayers = layers;
switch (gridType) {
case 1:
totalLayers = layers;
break;
case 2:
totalLayers = (1 - Math.sqrt( (x)** 2 + (y)**2) / 100) * layers | 0;
break;
case 3:
totalLayers = (1 - Math.sqrt( (x+y)** 2 + (y+x)**2) / 100) * layers | 0;
break;
case 4:
totalLayers = lerp(1, layers, (Math.cos(gridY * 5 + gridX * 10)/2 + 0.5) ) | 0;
break;
case 5:
totalLayers = lerp(1, layers, (Math.sin(gridX + gridY*5)/2 + 0.5) * (Math.sin(gridY + gridX*5)/2 + 0.5) ) | 0;
break;
case 6:
totalLayers = lerp(1, layers, Math.random() ) | 0;
break;
}

for (let idx=0; idx<totalLayers; idx++) {
const t = idx / (totalLayers-1);
let id = totalLayers - idx;
const offset = [0, id * sizeY * -layerDistance];
const rect = polygons.create();

if (hatchType) {
if (hatchType === 1 && t > 0) {
if (t > 0.75) rect.addHatching(Math.atan2(diamondHeight, diamondWidth), 0.5)
if (t >= 0.5) rect.addHatching(Math.PI/2, 0.75 )
if (t > 0) rect.addHatching(0, 0.75 )
} else if (hatchType == 2 && t > 0) {
rect.addHatching(Math.atan2(diamondHeight, diamondWidth *  (idx % 2 ==0 ? 1 : -1)), lerp(minHatching, maxHatching, t))
} else if (hatchType === 3) {
if (Math.random() > 0.5) rect.addHatching(Math.atan2(diamondHeight, diamondWidth), 0.75);
if (Math.random() > 0.5) rect.addHatching(Math.atan2(diamondHeight, -diamondWidth), 0.75);
if (Math.random() > 0.5) rect.addHatching(0, 0.75);
if (Math.random() > 0.5) rect.addHatching(Math.PI/2, 0.75);
}  else if (hatchType === 4) {
if (Math.random() > 0.5) rect.addHatching(Math.random() * Math.PI, lerp(minHatching * 0.5, maxHatching, t));
}
}

polygons.draw(turtle, rect);
}

return i < grid*grid-1;
}

const lerp=(a,b,t)=>a+(b-a)*t;

////////////////////////////////////////////////////////////////
// Polygon Clipping utility code - Created by Reinder Nijhoff 2019
// https://turtletoy.net/turtle/a5befa1f8d
////////////////////////////////////////////////////////////////

function Polygons() {
const polygonList = [];
const Polygon = class {
constructor() {
this.cp = [];       // clip path: array of [x,y] pairs
this.dp = [];       // 2d lines [x0,y0],[x1,y1] to draw
this.aabb = [];     // AABB bounding box
}
// add point to clip path and update bounding box
let xmin = 1e5, xmax = -1e5, ymin = 1e5, ymax = -1e5;
(this.cp = [...this.cp, ...points]).forEach( p => {
xmin = Math.min(xmin, p[0]), xmax = Math.max(xmax, p[0]);
ymin = Math.min(ymin, p[1]), ymax = Math.max(ymax, p[1]);
});
this.aabb = [(xmin+xmax)/2, (ymin+ymax)/2, (xmax-xmin)/2, (ymax-ymin)/2];
}
// add segments (each a pair of points)
points.forEach(p => this.dp.push(p));
}
for (let i = 0, l = this.cp.length; i < l; i++) {
this.dp.push(this.cp[i], this.cp[(i + 1) % l]);
}
}
draw(t) {
for (let i = 0, l = this.dp.length; i < l; i+=2) {
t.jump(this.dp[i]), t.goto(this.dp[i + 1]);
}
}
const tp = new Polygon();
tp.cp.push([-1e5,-1e5],[1e5,-1e5],[1e5,1e5],[-1e5,1e5]);
const dx = Math.sin(a) * d,   dy = Math.cos(a) * d;
const cx = Math.sin(a) * 200, cy = Math.cos(a) * 200;
for (let i = 0.5; i < 150 / d; i++) {
tp.dp.push([dx * i + cy,   dy * i - cx], [dx * i - cy,   dy * i + cx]);
tp.dp.push([-dx * i + cy, -dy * i - cx], [-dx * i - cy, -dy * i + cx]);
}
tp.boolean(this, false);
this.dp = [...this.dp, ...tp.dp];
}
inside(p) {
let int = 0; // find number of i ntersection points from p to far away
for (let i = 0, l = this.cp.length; i < l; i++) {
if (this.segment_intersect(p, [0.1, -1000], this.cp[i], this.cp[(i + 1) % l])) {
int++;
}
}
return int & 1; // if even your outside
}
boolean(p, diff = true) {
// bouding box optimization by ge1doot.
if (Math.abs(this.aabb[0] - p.aabb[0]) - (p.aabb[2] + this.aabb[2]) >= 0 &&
Math.abs(this.aabb[1] - p.aabb[1]) - (p.aabb[3] + this.aabb[3]) >= 0) return this.dp.length > 0;

// polygon diff algorithm (narrow phase)
const ndp = [];
for (let i = 0, l = this.dp.length; i < l; i+=2) {
const ls0 = this.dp[i];
const ls1 = this.dp[i + 1];
// find all intersections with clip path
const int = [];
for (let j = 0, cl = p.cp.length; j < cl; j++) {
const pint = this.segment_intersect(ls0, ls1, p.cp[j], p.cp[(j + 1) % cl]);
if (pint !== false) {
int.push(pint);
}
}
if (int.length === 0) {
// 0 intersections, inside or outside?
if (diff === !p.inside(ls0)) {
ndp.push(ls0, ls1);
}
} else {
int.push(ls0, ls1);
// order intersection points on line ls.p1 to ls.p2
const cmpx = ls1[0] - ls0[0];
const cmpy = ls1[1] - ls0[1];
int.sort( (a,b) =>  (a[0] - ls0[0]) * cmpx + (a[1] - ls0[1]) * cmpy -
(b[0] - ls0[0]) * cmpx - (b[1] - ls0[1]) * cmpy);

for (let j = 0; j < int.length - 1; j++) {
if ((int[j][0] - int[j+1][0])**2 + (int[j][1] - int[j+1][1])**2 >= 0.001) {
if (diff === !p.inside([(int[j][0]+int[j+1][0])/2,(int[j][1]+int[j+1][1])/2])) {
ndp.push(int[j], int[j+1]);
}
}
}
}
}
return (this.dp = ndp).length > 0;
}
//port of http://paulbourke.net/geometry/pointlineplane/Helpers.cs
segment_intersect(l1p1, l1p2, l2p1, l2p2) {
const d   = (l2p2[1] - l2p1[1]) * (l1p2[0] - l1p1[0]) - (l2p2[0] - l2p1[0]) * (l1p2[1] - l1p1[1]);
if (d === 0) return false;
const n_a = (l2p2[0] - l2p1[0]) * (l1p1[1] - l2p1[1]) - (l2p2[1] - l2p1[1]) * (l1p1[0] - l2p1[0]);
const n_b = (l1p2[0] - l1p1[0]) * (l1p1[1] - l2p1[1]) - (l1p2[1] - l1p1[1]) * (l1p1[0] - l2p1[0]);
const ua = n_a / d;
const ub = n_b / d;
if (ua >= 0 && ua <= 1 && ub >= 0 && ub <= 1) {
return [l1p1[0] + ua * (l1p2[0] - l1p1[0]), l1p1[1] + ua * (l1p2[1] - l1p1[1])];
}
return false;
}
};
return {
list: () => polygonList,
create: () => new Polygon(),
draw: (turtle, p, addToVisList=true) => {
for (let j = 0; j < polygonList.length && p.boolean(polygonList[j]); j++);
p.draw(turtle);