Source: core/renderers/webgl/utils/Quad.js

/**
 * Helper class to create a quad
 *
 * @class
 * @memberof PIXI
 * @param gl {WebGLRenderingContext} The gl context for this quad to use.
 */
function Quad(gl)
{
    /*
     * the current WebGL drawing context
     *
     * @member {WebGLRenderingContext}
     */
    this.gl = gl;

//    this.textures = new TextureUvs();

    /**
     * An array of vertices
     *
     * @member {Float32Array}
     */
    this.vertices = new Float32Array([
        0,0,
        200,0,
        200,200,
        0,200
    ]);

    /**
     * The Uvs of the quad
     *
     * @member {Float32Array}
     */
    this.uvs = new Float32Array([
        0,0,
        1,0,
        1,1,
        0,1
    ]);

//    var white = (0xFFFFFF >> 16) + (0xFFFFFF & 0xff00) + ((0xFFFFFF & 0xff) << 16) + (1 * 255 << 24);
    //TODO convert this to a 32 unsigned int array
    /**
     * The color components of the triangles
     *
     * @member {Float32Array}
     */
    this.colors = new Float32Array([
        1,1,1,1,
        1,1,1,1,
        1,1,1,1,
        1,1,1,1
    ]);

    /*
     * @member {Uint16Array} An array containing the indices of the vertices
     */
    this.indices = new Uint16Array([
        0, 1, 2, 0, 3, 2
    ]);

    /*
     * @member {WebGLBuffer} The vertex buffer
     */
    this.vertexBuffer = gl.createBuffer();

    /*
     * @member {WebGLBuffer} The index buffer
     */
    this.indexBuffer = gl.createBuffer();

    gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, (8 + 8 + 16) * 4, gl.DYNAMIC_DRAW);

    gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.indexBuffer);
    gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, this.indices, gl.STATIC_DRAW);

    this.upload();
}

Quad.prototype.constructor = Quad;

/**
 * Maps two Rectangle to the quad
 * @param rect {PIXI.Rectangle} the first rectangle
 * @param rect2 {PIXI.Rectangle} the second rectangle
 */
Quad.prototype.map = function(rect, rect2)
{
    var x = 0; //rect2.x / rect.width;
    var y = 0; //rect2.y / rect.height;

    this.uvs[0] = x;
    this.uvs[1] = y;

    this.uvs[2] = x + rect2.width / rect.width;
    this.uvs[3] = y;

    this.uvs[4] = x + rect2.width / rect.width;
    this.uvs[5] = y + rect2.height / rect.height;

    this.uvs[6] = x;
    this.uvs[7] = y + rect2.height / rect.height;

    /// -----
    x = rect2.x;
    y = rect2.y;

    this.vertices[0] = x;
    this.vertices[1] = y;

    this.vertices[2] = x + rect2.width;
    this.vertices[3] = y;

    this.vertices[4] = x + rect2.width;
    this.vertices[5] = y + rect2.height;

    this.vertices[6] = x;
    this.vertices[7] = y + rect2.height;

    this.upload();
};

/**
 * Binds the buffer and uploads the data
 */
Quad.prototype.upload = function()
{
    var gl = this.gl;

    // TODO could probably be pushed into one upload!
    gl.bindBuffer( gl.ARRAY_BUFFER, this.vertexBuffer );

    gl.bufferSubData(gl.ARRAY_BUFFER, 0, this.vertices);

    gl.bufferSubData(gl.ARRAY_BUFFER, 8 * 4, this.uvs);

    gl.bufferSubData(gl.ARRAY_BUFFER, (8 + 8) * 4, this.colors);
};

Quad.prototype.destroy = function()
{
    var gl = this.gl;
    
     gl.deleteBuffer(this.vertexBuffer);
     gl.deleteBuffer(this.indexBuffer);
};

module.exports = Quad;