The SDK is too object oriented

I don't think it's a bad SDK personally, but when I had to port Quake3 to use the SDK (Quake3 is in pure C) I couldn't link statically to the SDK, so I had to create an intermediate DLL between them.. Real easy, 4 functions and it will do the job..

Honestly, I don't have my rift, so I couldn't test it yet, but it looks like this.. Good or not, I'll let you be the judge!

libovrwrapper.h

#ifdef LIBOVRWRAPPER_EXPORTS
	#if defined __cplusplus
		#define LIBOVRWRAPPER_API extern "C" __declspec(dllexport)
	#else
		#define LIBOVRWRAPPER_API __declspec(dllexport)
	#endif
#else
	#if defined __cplusplus
		#define LIBOVRWRAPPER_API extern "C" __declspec(dllimport)
	#else
		#define LIBOVRWRAPPER_API __declspec(dllimport)
	#endif
#endif

struct OVR_HMDInfo
{	
	unsigned      HResolution;
	unsigned      VResolution; 
    float         HScreenSize;
	float         VScreenSize;
    float         VScreenCenter;
    float         EyeToScreenDistance;
    float         LensSeparationDistance;
    float         InterpupillaryDistance;
    float         DistortionK[4];
    int           DesktopX;
	int           DesktopY;
    char          DisplayDeviceName[32];
};


LIBOVRWRAPPER_API int   OVR_Init();
LIBOVRWRAPPER_API void  OVR_Exit();
LIBOVRWRAPPER_API int   OVR_QueryHMD(struct OVR_HMDInfo* refHmdInfo);
LIBOVRWRAPPER_API int   OVR_Peek(float* yaw, float* pitch, float* roll);

libovrwrapper.cpp

#include "libovrwrapper.h"
#include <OVR.h>

using namespace OVR;

// Ptr<> AddRef'ed, AutoCleaned
bool               bInited = false;
Ptr<DeviceManager> pManager;
Ptr<HMDDevice>     pHMD;
Ptr<SensorDevice>  pSensor;
SensorFusion       pSensorFusion;


LIBOVRWRAPPER_API int OVR_Init()
{
	bInited = false;
	System::Init(Log::ConfigureDefaultLog(LogMask_Regular));

	if (System::IsInitialized())
	{
		int stage = -1;
		while (++stage > -1 && !bInited)
		{
			switch (stage)
			{
				case 0:
					pManager = *DeviceManager::Create();
					if (pManager == NULL)
						return bInited;
					break;
				case 1:
					pHMD     = *pManager->EnumerateDevices<HMDDevice>().CreateDevice();
					if (pHMD == NULL)
						return bInited;
					break;
				case 2:
					pSensor = *pHMD->GetSensor();
					if (pSensor == NULL)
						return bInited;
					break;
				default:
					bInited = true;
					break;
			};
		}
	}

	pSensorFusion.AttachToSensor(pSensor);

	return (bInited?1:0);
}


LIBOVRWRAPPER_API void OVR_Exit()
{
	if (bInited)
	{
		System::Destroy();
	}
}


LIBOVRWRAPPER_API int OVR_QueryHMD(OVR_HMDInfo* refHmdInfo)
{
	if (!bInited)
	{
		return 0;
	}

	HMDInfo src;
	if (pHMD->GetDeviceInfo(&src))
	{
		refHmdInfo->HResolution             = src.HResolution;
        refHmdInfo->VResolution             = src.VResolution;
        refHmdInfo->HScreenSize             = src.HScreenSize;
        refHmdInfo->VScreenSize             = src.VScreenSize;
        refHmdInfo->VScreenCenter           = src.VScreenCenter;
        refHmdInfo->EyeToScreenDistance     = src.EyeToScreenDistance;
        refHmdInfo->LensSeparationDistance  = src.LensSeparationDistance;
        refHmdInfo->InterpupillaryDistance  = src.InterpupillaryDistance;
        refHmdInfo->DistortionK[0]          = src.DistortionK[0];
        refHmdInfo->DistortionK[1]          = src.DistortionK[1];
        refHmdInfo->DistortionK[2]          = src.DistortionK[2];
        refHmdInfo->DistortionK[3]          = src.DistortionK[3];
        refHmdInfo->DesktopX                = src.DesktopX;
        refHmdInfo->DesktopY                = src.DesktopY;
        memcpy(refHmdInfo->DisplayDeviceName, src.DisplayDeviceName, sizeof(refHmdInfo->DisplayDeviceName));        
	}

	return 1;
}


LIBOVRWRAPPER_API int OVR_Peek(float* yaw, float* pitch, float* roll)
{
	if (!bInited)
	{
		return 0;
	}

	Quatf hmdOrient = pSensorFusion.GetOrientation();
	hmdOrient.GetEulerAngles<Axis_Y, Axis_X, Axis_Z>(yaw, pitch, roll);

	return 1;
}