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const turtle = new Turtle();
const polygons = new Polygons();
function walk(i) {
const shape = polygons.create();
let starRotation = 0.0; // min=0, max=3.14, step=0.001;
PolygonsUtil.star(shape, 0, 0, 90, 45, 6, starRotation, false);
let inner = 0;
let outer = 0;
let iterations = 12; // min=4, max=40, step=1
let rotation = 0.0;
let outerStep = 19; // min=10, max=40, step=1
let innerStep = 8; // min=2, max=40, step=1
let rotationStep = 0.478; // min=0.0, max=2, step=0.001
for (let ii=0; ii<outerStep; ii++) {
PolygonsUtil.star(shape, 0, 0, inner += innerStep, outer += outerStep, iterations, rotation+=rotationStep, true);
}
shape.boolean(shape, false);
shape.addOutline();
polygons.draw(turtle, shape, true);
const outline = polygons.create();
PolygonsUtil.star(outline, 0, 0, 95, 48.5, 6, starRotation, false);
outline.addOutline();
polygons.draw(turtle, outline, true);
}
////////////////////////////////////////////////////////////////
// Polygon utility code - Created by Mark Knol 2019
// https://turtletoy.net/turtle/5ef089d251
////////////////////////////////////////////////////////////////
class PolygonsUtil {
static circle(polygon, x, y, radius = 10, segments = 45, useSegments = false) {
for (let ii = 0; ii <= segments; ii++) {
const a = ii / segments * Math.PI * 2;
if (useSegments) {
const a2 = (ii+1) / segments * Math.PI * 2;
polygon.addSegments([x + Math.cos(a) * radius, y + Math.sin(a) * radius], [x + Math.cos(a2) * radius, y + Math.sin(a2) * radius]);
} else {
polygon.addPoints([x + Math.cos(a) * radius, y + Math.sin(a) * radius]);
}
}
}
static rect(polygon, x, y, width, height) {
polygon.addPoints([x, y], [x + width, y], [x + width, y + height], [x, y + height]);
}
static star(polygon, x, y, radiusInner = 30, radiusOuter = radiusInner * 0.3, corners = 4, rotation = 0.0, useSegments = true) {
const segments = corners * 2;
for (let ii = 0; ii <= segments; ii++) {
const a = ii / segments * Math.PI * 2;
const radius = ii & 1 ? radiusInner : radiusOuter;
if (useSegments) {
const a2 = (ii+1) / segments * Math.PI * 2;
const radius2 = (ii+1) & 1 ? radiusInner : radiusOuter;
polygon.addSegments([x + Math.cos(rotation + a) * radius, y + Math.sin(rotation + a) * radius], [x + Math.cos(rotation + a2) * radius2, y + Math.sin(rotation + a2) * radius2]);
} else {
polygon.addPoints([x + Math.cos(rotation + a) * radius, y + Math.sin(rotation + a) * radius]);
}
}
}
static starParts(polygon, odd, x, y, radiusInner = 30, radiusOuter = radiusInner * 0.3, corners = 4, rotation = 0.0) {
const segments = corners * 2;
const start = 0;
for (let ii = 0; ii <= segments; ii++) {
const a = ii / segments * Math.PI * 2;
let radius = ii % 2 == 1 ? radiusInner : radiusOuter;
if (radius == radiusInner && !odd) polygon.addPoints([x, y]);
polygon.addPoints([x + Math.cos(rotation + a) * radius, y + Math.sin(rotation +a) * radius]);
if (radius == radiusInner && odd) polygon.addPoints([x, y]);
}
}
}
////////////////////////////////////////////////////////////////
// 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
}
addPoints(...points) {
// 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];
}
addSegments(...points) {
// add segments (each a pair of points)
points.forEach(p => this.dp.push(p));
}
addOutline() {
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]);
}
}
addHatching(a, d) {
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);
if (addToVisList) polygonList.push(p);
}
};
}