def extractMat(mat):
    """
    Return matrix in glTF column-major order
    """
    return [mat[0][0], mat[1][0], mat[2][0], mat[3][0],
            mat[0][1], mat[1][1], mat[2][1], mat[3][1],
            mat[0][2], mat[1][2], mat[2][2], mat[3][2],
            mat[0][3], mat[1][3], mat[2][3], mat[3][3]]