Triangle.js

/**
 * The MIT License (MIT)
 *
 * Copyright (c) 2015 Famous Industries Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

'use strict';

var Geometry = require('../Geometry');
var GeometryHelper = require('../GeometryHelper');

/**
 * This function returns a new static geometry, which is passed
 * custom buffer data.
 *
 * @class Triangle
 * @constructor
 *
 * @param {Object} options Parameters that alter the
 * vertex buffers of the generated geometry.
 *
 * @return {Object} constructed geometry
 */
function Triangle (options) {
    options  = options || {};
    var detail   = options.detail || 1;
    var normals  = [];
    var textureCoords = [
        0.0, 0.0,
        0.5, 1.0,
        1.0, 0.0
    ];
    var indices  = [
        0, 1, 2
    ];
    var vertices = [
        -1, -1, 0,
         0,  1, 0,
         1, -1, 0
    ];

    while(--detail) GeometryHelper.subdivide(indices, vertices, textureCoords);

    if (options.backface !== false) {
        GeometryHelper.addBackfaceTriangles(vertices, indices);
    }

    normals = GeometryHelper.computeNormals(vertices, indices);

    return new Geometry({
        buffers: [
            { name: 'a_pos', data: vertices },
            { name: 'a_texCoord', data: textureCoords, size: 2 },
            { name: 'a_normal', data: normals },
            { name: 'indices', data: indices, size: 1 }
        ]
    });
}

module.exports = Triangle;