Get region IDs for the currently available draw devices
int PdGetDevices( PhRid_t *rid_array, uint32_t max_rids );
PdGetDevices() fills the provided rid_array with up to max_rids region IDs of draw devices that are currently available.
The number of draw devices currently available on the system. This value may be larger than max_rids, which indicates that the provided array isn't big enough to hold the region IDs for all the draw devices on the system.
“Video memory offscreen” in the Raw Drawing and Animation chapter of the Photon Programmer's Guide