nuclear@25: Initialization
nuclear@25: --------------
nuclear@25: 
nuclear@25: Before calling any other function you need to initialize the VR library by
nuclear@25: calling ``vr_init``. Similarly, ``vr_shutdown`` frees up all resources held by
nuclear@25: the library.
nuclear@25: 
nuclear@25: Libgoatvr has a number of backend modules for interfacing with VR headsets, and
nuclear@25: there might be multiple modules compiled with your version of libgoatvr. If you
nuclear@25: don't want to rely on the built-in defaults, you might want to enumerate and
nuclear@25: select which module to use.
nuclear@25: 
nuclear@25: The following example initializes the library, and prints the list of available
nuclear@25: VR modules:
nuclear@25: 
nuclear@25: .. code:: c
nuclear@25: 
nuclear@25:  #include <stdio.h>
nuclear@25:  #include <goatvr.h>
nuclear@25:  
nuclear@25:  int main(void)
nuclear@25:  {
nuclear@25:  	int i, nmod;
nuclear@25:  
nuclear@25:  	if(vr_init() == -1) {
nuclear@25:  		fprintf(stderr, "failed to initialize goatvr\n");
nuclear@25:  		return 1;
nuclear@25:  	}
nuclear@25:  
nuclear@25:  	nmod = vr_module_count();
nuclear@25:  	printf("There are %d modules:\n", nmod);
nuclear@25:  	for(i=0; i<nmod; i++) {
nuclear@25:  		printf(" %2d - %s\n", i, vr_module_name(i));
nuclear@25:  	}
nuclear@25:  	vr_shutdown();
nuclear@25:  	return 0;
nuclear@25:  }
nuclear@25:  
nuclear@25: Running this on my computer, with the Oculus Rift DK2 connected, and oculusd
nuclear@25: running, produces this output::
nuclear@25: 
nuclear@25:  initialized LibOVR 0.4.4
nuclear@25:  1 Oculus HMD(s) found
nuclear@25:   [0]: Oculus VR - Oculus Rift DK2
nuclear@25:  using vr module: libovr
nuclear@25:  There are 2 modules:
nuclear@25:    0 - libovr
nuclear@25:    1 - null
nuclear@25: 
nuclear@25: The first four lines come from the initialization of the ``libovr`` module which
nuclear@25: is selected by default if it's available. If however I turn off the DK2 or stop
nuclear@25: the daemon, then I'm getting just the ``null`` module in this list.
nuclear@25: 
nuclear@25: If you'd like to override the default selected module, and use the ``null``
nuclear@25: module instead of ``libovr``, which is useful during development to avoid having
nuclear@25: to put the HMD on and off all the time, you can call ``vr_use_module(1)``, or
nuclear@25: ``vr_use_module_named("null")``.