Это не оно?
"RiIlluminate ( RtLightHandle light, RtBoolean onoff )
If onoff is RI TRUE and the light source referred to by the RtLightHandle is not
currently in the current light source list, add it to the list. If onoff is RI FALSE and the
light source referred to by the RtLightHandle is currently in the current light source
list, remove it from the list. Note that popping the graphics state restores the onoff
value of all lights to their previous values.
RIB BINDING
Illuminate sequencenumber onoff"