true
if the fragment is back facing; otherwise, false
.\n\
*/\n\
bool czm_backFacing()\n\
{\n\
// !gl_FrontFacing doesn't work as expected on Mac/Intel so use the more verbose form instead. See https://github.com/CesiumGS/cesium/pull/8494.\n\
return gl_FrontFacing == false;\n\
}\n\
";