modeling/src/maths/mat4/isIdentity.js

/**
 * Determine whether the given matris is the identity transform.
 * This is equivalent to (but much faster than):
 *
 *     mat4.equals(mat4.create(), matrix)
 *
 * @param {mat4} matrix - the matrix
 * @returns {Boolean} true if matrix is the identity transform
 * @alias module:modeling/maths/mat4.isIdentity
 * @example
 * if (mat4.isIdentity(mymatrix)) ...
 */
const isIdentity = (matrix) => (
  matrix[0] === 1 && matrix[1] === 0 && matrix[2] === 0 && matrix[3] === 0 &&
  matrix[4] === 0 && matrix[5] === 1 && matrix[6] === 0 && matrix[7] === 0 &&
  matrix[8] === 0 && matrix[9] === 0 && matrix[10] === 1 && matrix[11] === 0 &&
  matrix[12] === 0 && matrix[13] === 0 && matrix[14] === 0 && matrix[15] === 1
)

module.exports = isIdentity