# check if DRI is available, show an error and exit if it isn't
function checkDriOK ()
{
  if [ "`glxinfo | grep "direct rendering: " | head -n 1 | cut -d " " -f 3`" != Yes ] ||
     glxinfo | grep -q "OpenGL renderer string: Software Rasterizer"; then
    zenity --error --text="Your system currently is not capable of hardware \
accelerated 3D. Therefore $1 cannot run.

Usually the cause of this error is that there are no Free Software drivers \
for your graphics card, please contact your graphics card manufacturer and \
kindly ask them to provide Free Software support for your card."
    exit 1;
  fi
}