gl-mat4/fromXRotation.js

gl-matrix's mat4, split into smaller pieces

module.exports = fromXRotation

/**
 * Creates a matrix from the given angle around the X axis
 * This is equivalent to (but much faster than):
 *
 *     mat4.identity(dest)
 *     mat4.rotateX(dest, dest, rad)
 *
 * @param {mat4} out mat4 receiving operation result
 * @param {Number} rad the angle to rotate the matrix by
 * @returns {mat4} out
 */
function fromXRotation(out, rad) {
    var s = Math.sin(rad),
        c = Math.cos(rad)

    // Perform axis-specific matrix multiplication
    out[0] = 1
    out[1] = 0
    out[2] = 0
    out[3] = 0
    out[4] = 0
    out[5] = c
    out[6] = s
    out[7] = 0
    out[8] = 0
    out[9] = -s
    out[10] = c
    out[11] = 0
    out[12] = 0
    out[13] = 0
    out[14] = 0
    out[15] = 1
    return out
}