nanogl-primitives-2d/circle-outline.js

2d Primitives for nanogl

import GLArrayBuffer from 'nanogl/arraybuffer';
export default class CircleOutline extends GLArrayBuffer {
    constructor(gl, radius = 1.0, segs = 32, thickness = 0.1) {
        super(gl);
        const a = new Float32Array((segs + 1) * 10);
        const inner = radius - thickness;
        const tcMult = (inner / radius) * 0.5;
        const arc = Math.PI * 2 / segs;
        for (var i = 0; i <= segs + 1; i++) {
            var x = Math.cos(i * arc);
            var y = -Math.sin(i * arc);
            var j = i * 10;
            a[j + 0] = radius * x;
            a[j + 1] = radius * y;
            a[j + 2] = x * 0.5 + 0.5;
            a[j + 3] = y * 0.5 + 0.5;
            a[j + 5] = inner * x;
            a[j + 6] = inner * y;
            a[j + 7] = x * tcMult + 0.5;
            a[j + 8] = y * tcMult + 0.5;
            a[j + 4] = 1;
            a[j + 9] = 0;
        }
        this.data(a);
        this.attrib('aPosition', 2, gl.FLOAT);
        this.attrib('aTexCoord', 2, gl.FLOAT);
        this.attrib('aSide', 1, gl.FLOAT);
    }
    render() {
        this.drawTriangleStrip();
    }
}