Irrlicht/Ogre - Rift integration

So, aside from running the Irrlicht scene through a distortion renderer, is mostly a matter of mapping the Yaw, Pitch and Roll parameters from the Oculus SDK to camera node in Irrlicht?

Basicly, ovrHmd_BeginEyeRender() returns you a "pose" containing both the orientation quaternion and a position vector.

You use thouses info to set the camera position and orientation.

Using quaternion in Ogre I do this :

        //Get the eye pose
        ovrPosef eyePose = ovrHmd_BeginEyeRender(hmd, eye);
        
        //Get the hmd orientation
        OVR::Quatf camOrient = eyePose.Orientation;
        
        //Compute the projection matrix from FOV and clipping planes distances
        OVR::Matrix4f proj = ovrMatrix4f_Projection(EyeRenderDesc[eye].Fov,nearClippingDistance,10000.0f, true);

        //Convert it to Ogre matrix
        Ogre::Matrix4 OgreProj;
        for(char x(0); x < 4; x++)
            for(char y(0); y < 4; y++)
                OgreProj[x][y] = proj.M[x][y];
        
        //Set the matrix
        cams[eye]->setCustomProjectionMatrix(true, OgreProj);
        
        //Set the orientation
        cams[eye]->setOrientation(cameraOrientation * Ogre::Quaternion(camOrient.w,camOrient.x,camOrient.y,camOrient.z));

        //Set Position
        cams[eye]->setPosition( cameraPosition +
                (cams[eye]->getOrientation() *
                 - //For some reason cams are inverted here. Take the oposite vector
                 Ogre::Vector3(
                     EyeRenderDesc[eye].ViewAdjust.x,
                     EyeRenderDesc[eye].ViewAdjust.y,
                     EyeRenderDesc[eye].ViewAdjust.z))
                );

"cameraPosition" & "cameraOrientation" are the position/orientation value the game logic whants the cameras to be. These are the value I manupulate for mouving the player into space.

You also have to aply the projection matrix given by the OculusSDK to the camera. Don't know how it works with Irrlicht.

I aslo adjust the "nearClippingDistance" of the projection matrix because I put cameras inside of players mesh model head.

Thouse thing have to be done each frames and for both left and right cameras.

If you want an example I've done with Ogre, you can see it here : https://github.com/Ybalrid/OgreOculusRenderer/blob/master/OgreOculusRender.cpp (see the "OgreOculusRender::RenderOneFrame" method)

As I remember with Irrlicht the only way to correctly orient a camera is to set the "look at" and "up" vector position. You can easily get them with a little bit of math.

Hope it helps! ^^"