joshtynjala / kha-extension-fill-complex-polygon

Similar to GraphicsExtension.fillPolygon(), but can also fill polygons that are not convex

kha-extension-fill-complex-polygon

An extension for Kha that includes a fillComplexPolygon() function for kha.graphics2.Graphics. This function is similar to fillPolygon(), but it can also fill polygons that are not convex. Uses the earcut polygon triangulation library.

Comparison with fillPolygon()

The following screenshot compares the more advanced triangulation of fillComplexPolygon() to the basic fillPolygon(). The supplied vertices represent a star with five points, which is a non-convex shape that fillPolygon() does not render correctly.

Installation

Install from the Github repository using the following command:

haxelib git kha-extension-fill-complex-polygon https://github.com/joshtynjala/kha-extension-fill-complex-polygon.git

Usage

import kha.math.Vector2;
using org.josht.kha.graphics2.GraphicsExtension;

var vertices:Array<Vector2> = [];
// draws a star with 5 points
var points = 5;
var outerRadius = 100.0;
var innerRadius = 38.0;
var startOffset = -Math.PI / 2.0;
var angle = Math.PI / points;
for (i in 0...(2 * points + 1)) {
  var radius = i % 2 == 0 ? outerRadius : innerRadius;
  var x = Math.cos(startOffset + angle * i) * radius;
  var y = Math.sin(startOffset + angle * i) * radius;
  vertices.push(new Vector2(outerRadius + x, outerRadius + y));
}
g2.color = Red;
g2.fillComplexPolygon(20.0, 20.0, vertices);