fromRotationTranslation.js

module.exports = fromRotationTranslation;

/**
 * Creates a matrix from a quaternion rotation and vector translation
 * This is equivalent to (but much faster than):
 *
 *     mat4.identity(dest);
 *     mat4.translate(dest, vec);
 *     var quatMat = mat4.create();
 *     quat4.toMat4(quat, quatMat);
 *     mat4.multiply(dest, quatMat);
 *
 * @param {mat4} out mat4 receiving operation result
 * @param {quat4} q Rotation quaternion
 * @param {vec3} v Translation vector
 * @returns {mat4} out
 */
function fromRotationTranslation(out, q, v) {
    // Quaternion math
    var x = q[0], y = q[1], z = q[2], w = q[3],
        x2 = x + x,
        y2 = y + y,
        z2 = z + z,

        xx = x * x2,
        xy = x * y2,
        xz = x * z2,
        yy = y * y2,
        yz = y * z2,
        zz = z * z2,
        wx = w * x2,
        wy = w * y2,
        wz = w * z2;

    out[0] = 1 - (yy + zz);
    out[1] = xy + wz;
    out[2] = xz - wy;
    out[3] = 0;
    out[4] = xy - wz;
    out[5] = 1 - (xx + zz);
    out[6] = yz + wx;
    out[7] = 0;
    out[8] = xz + wy;
    out[9] = yz - wx;
    out[10] = 1 - (xx + yy);
    out[11] = 0;
    out[12] = v[0];
    out[13] = v[1];
    out[14] = v[2];
    out[15] = 1;
    
    return out;
};