Using pdf_rotate()
The pdf_rotate() function is used in a similar way allowing you to rotate the coordinate system around the origin. Very useful for rendering text at an angle (for example)

Rendering Text at an angle
<?php
    /* Save the current state */
    pdf_save($pdf_r);

    /* Rotate the orgin 45 degrees */
    pdf_rotate($pdf_r, 45);
    
    /* Write some text */
    pdf_set_font($pdf_r, "Helvetica-Oblique", 18, "host");
    pdf_show_xy($pdf_r, "Angled Text", 20, 20);
    
    /* Restore the coordinate system */
    pdf_restore($pdf_r);
?>