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https://github.com/floorplanner/polygon-tools
Polygon tools
https://github.com/floorplanner/polygon-tools
glu polygon tesselation triangulation
Last synced: 3 months ago
JSON representation
Polygon tools
- Host: GitHub
- URL: https://github.com/floorplanner/polygon-tools
- Owner: floorplanner
- License: mit
- Created: 2017-04-22T13:03:49.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2023-02-23T15:25:26.000Z (almost 2 years ago)
- Last Synced: 2024-09-19T09:41:26.408Z (3 months ago)
- Topics: glu, polygon, tesselation, triangulation
- Language: JavaScript
- Size: 439 KB
- Stars: 34
- Watchers: 6
- Forks: 5
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
## polygon-tools
Polygon tools.
### install
npm i polygon-tools
## browser
The minified code is availabe through S3:
https://fpcdn.s3.amazonaws.com/apps/polygon-tools/0.4.6/polygon-tools.min.js
### build
Build minified javascript for use in browser:
npm run build
The library is exposed as ```PolygonTools```.
```javascript
var polygon = [
[0, 0],
[100, 0],
[100, 100],
[0, 100]
];
var area = PolygonTools.polygon.area(polygon);
```
### documentation
Documentation is available [here](https://floorplanner.github.io/polygon-tools/).
### examples
- [Union](https://jsfiddle.net/timknip/2tjkuvvj/)
- [Subtract](https://jsfiddle.net/timknip/jz7do1fy/)
- [Intersection](https://jsfiddle.net/timknip/fqh3d0t1/)
- [Triangulate](https://jsfiddle.net/timknip/hs2adah7/)
- [Tesselator](https://jsfiddle.net/timknip/4Lv0wd3q/)
- [Polygon Winding](https://jsfiddle.net/timknip/yuqa3o40/)
### polygon
Summary of polygon methods:
- ```area(pts)```
- ```normal(pts)```
- ```centroid(pts)```
- ```winding(pts)```
- ```is_cw(pts)```
- ```is_ccw(pts)```
```javascript
import {polygon} from 'polygon-tools';
const POLYGON = [
[0, 0],
[100, 0],
[100, 100],
[0, 100]
];
// Signed area - 2D only
let area = polygon.area(POLYGON);
// Polygon normal - both 2D and 3D polygons
let normal = polygon.normal(POLYGON);
// Polygon centroid - 2D only
let centroid = polygon.centroid(POLYGON);
// Polygon winding - 2D only
let winding = polygon.winding(POLYGON);
// result is one of:
const {WINDING_CW, WINDING_CCW, WINDING_UNKNOWN} = polygon;
// test for WINDING_CW
polygon.is_cw(POLYGON);
// test for WINDING_CCW
polygon.is_ccw(POLYGON);
```
### boolean operations
- ```union (...polygons)```
- ```subtract (...polygons)```
- ```intersection (a, b)```
```javascript
import {polygon} from 'polygon-tools';
const POLY_A = [
[0, 0],
[100, 0],
[100, 100],
[0, 100]
];
const POLY_B = [
[50, 50],
[150, 50],
[150, 150],
[50, 150]
];
// union(polyA, polyB, polyN, ...)
let union = polygon.union(POLY_A, POLY_B);
// subtract(polyA, polyB, polyN, ...)
// NOTE: poly B..N are subtracted from A
let subtract = polygon.subtract(POLY_A, POLY_B);
// intersection(polyA, polyB)
let intersection = polygon.intersection(POLY_A, POLY_B);
```
### triangulation
- ```triangulate(polygon, holes)```
```javascript
import {polygon} from 'polygon-tools';
const POLYGON = [
[0, 0],
[100, 0],
[100, 100],
[0, 100]
];
const HOLE = [
[30, 30],
[30, 70],
[70, 70],
[70, 30]
];
// returns an array of triangles
let triangles = polygon.triangulate(POLYGON, [HOLE]);
```
### using the tesselator
Instead of the convenience methods above, the tesselator
can also be used directly. Different vertex sizes can be used so vertex
attributes like UVs and normals are correctly interpolated.
```javascript
import {tesselator} from 'polygon-tools';
const POLYGON = [
[0, 0],
[100, 0],
[100, 100],
[0, 100]
];
const HOLE = [
[30, 30],
[30, 70],
[70, 70],
[70, 30]
];
let options = {
polygons: [POLYGON],
holes: [HOLE],
vertexSize: 2,
windingRule: tesselator.GLU_TESS_WINDING_POSITIVE,
boundaryOnly: false,
normal: null,
autoWinding: true
};
let triangles = tesselator.run(options);
```
### use with PIXI
Suppose we want a textured polygon with holes. In such cases we cannot
use ```polygon.subtract``` because any interior hole is returned as another
polygon. To create polygons with holes we need use triangulation.
Assuming we have the triangles (see above) and some texture:
```javascript
let sprite = new PIXI.Sprite(texture);
let mask = new PIXI.Graphics();
// create paths
let paths = triangles.map(tri => {
return tri.reduce((p, v) => {
return p.push(v[0], v[1]);
}, []);
});
paths.forEach(path => {
mask.beginFill(0xff0000);
mask.drawPolygon(path);
});
sprite.mask = mask;
sprite.addChild(mask);
```