Earcut has now been exposed and is available via Geom.Polygon.Earcut and is fully documented.

This commit is contained in:
Richard Davey 2020-08-25 09:54:03 +01:00
parent 408c828a6c
commit 1f50b49eff
2 changed files with 57 additions and 3 deletions

View file

@ -4,7 +4,60 @@
* @license {@link https://opensource.org/licenses/MIT|MIT License}
*/
// Earcut 2.2.2 (January 21st 2020)
/**
* This module implements a modified ear slicing algorithm, optimized by z-order curve hashing and extended to
* handle holes, twisted polygons, degeneracies and self-intersections in a way that doesn't guarantee correctness
* of triangulation, but attempts to always produce acceptable results for practical data.
*
* Example:
*
* ```javascript
* const triangles = Phaser.Geom.Polygon.Earcut([10,0, 0,50, 60,60, 70,10]); // returns [1,0,3, 3,2,1]
* ```
*
* Each group of three vertex indices in the resulting array forms a triangle.
*
* ```javascript
* // triangulating a polygon with a hole
* earcut([0,0, 100,0, 100,100, 0,100, 20,20, 80,20, 80,80, 20,80], [4]);
* // [3,0,4, 5,4,0, 3,4,7, 5,0,1, 2,3,7, 6,5,1, 2,7,6, 6,1,2]
*
* // triangulating a polygon with 3d coords
* earcut([10,0,1, 0,50,2, 60,60,3, 70,10,4], null, 3);
* // [1,0,3, 3,2,1]
* ```
*
* If you pass a single vertex as a hole, Earcut treats it as a Steiner point.
*
* If your input is a multi-dimensional array (e.g. GeoJSON Polygon), you can convert it to the format
* expected by Earcut with `Phaser.Geom.Polygon.Earcut.flatten`:
*
* ```javascript
* var data = earcut.flatten(geojson.geometry.coordinates);
* var triangles = earcut(data.vertices, data.holes, data.dimensions);
* ```
*
* After getting a triangulation, you can verify its correctness with `Phaser.Geom.Polygon.Earcut.deviation`:
*
* ```javascript
* var deviation = earcut.deviation(vertices, holes, dimensions, triangles);
* ```
* Returns the relative difference between the total area of triangles and the area of the input polygon.
* 0 means the triangulation is fully correct.
*
* For more information see https://github.com/mapbox/earcut
*
* @function Phaser.Geom.Polygon.Earcut
* @since 3.50.0
*
* @param {number[]} data - A flat array of vertex coordinate, like [x0,y0, x1,y1, x2,y2, ...]
* @param {number[]} [holeIndices] - An array of hole indices if any (e.g. [5, 8] for a 12-vertex input would mean one hole with vertices 57 and another with 811).
* @param {number} [dimensions=2] - The number of coordinates per vertex in the input array (2 by default).
*
* @return {number[]} An array of triangulated data.
*/
// Earcut 2.2.2 (January 21st 2020)
/*
* ISC License
@ -26,8 +79,6 @@
'use strict';
module.exports = earcut;
function earcut(data, holeIndices, dim) {
dim = dim || 2;
@ -702,3 +753,5 @@ earcut.flatten = function (data) {
}
return result;
};
module.exports = earcut;

View file

@ -9,6 +9,7 @@ var Polygon = require('./Polygon');
Polygon.Clone = require('./Clone');
Polygon.Contains = require('./Contains');
Polygon.ContainsPoint = require('./ContainsPoint');
Polygon.Earcut = require('./Earcut');
Polygon.GetAABB = require('./GetAABB');
Polygon.GetNumberArray = require('./GetNumberArray');
Polygon.GetPoints = require('./GetPoints');