1. Intro to Oculus
CPSC 585

2. Oculus 90Hz refresh rate 2 OLED panels 2,160 x 1,200 resolution
110-degree field of view (measured diagonally)
5x5 foot space to move in

3. General Workings Frames to render
The software requests your head position.
The CPU processes the scene for each eye.
The GPU renders the scenes.
The Oculus Compositor applies distortion and displays the scenes on the headset.
Position / Orientation of cameras (eyes)

4. Distortion
Scene to be rendered in split-screen stereo with half of the screen used for each eye
Asynchronous TimeWarp: used to smooth out literally unplayable games
Each image is slightly offset from one another creating the 3D effect
ATW is a technique that shifts the rendered image slightly to adjust for changes in head movement
Adaptive Queue Ahead – CPU can operate on head position at the same time rendering is occurring

5. Rendering to Oculus
Scene to be rendered in split-screen stereo with half of the screen used for each eye
Each image is slightly offset from one another creating the 3D effect

6. Rendering to Oculus Each eye is represented by a camera
Both of which are separated but parallel in direction
interpupillary distance (IPD): Human eye pupils are approximately 65 mm apart.
IPD can be set in user profile
Lenses can be physically adjusted as well
IPD

7. Eye Positions / Orientations
Oculus contains a bunch of sensors for tracking orientation
Another sensor is used for translation

8. Initialize SDK ovr_Initialize(sdkParams)
sdkParams as nullptr uses default values
LogCallback
Initialize Oculus SDK

9. Initialize HMD ovr_Create(&session, &luid) luid
Handle to graphics card that has the HMD attached
hmdDesc = ovr_GetHmdDesc(session)
Resolution
Refresh Rate
DefaultEyeFov
Etc….
Create an ovrSession object for the headset
Compute the desired FOV and texture sizes based on ovrHmdDesc data

10. Initialize buffers for each eye
ovrSizei ovr_GetFovTextureSize(…)
Calculates the recommended viewport size for eye given fov
ovr_CreateTextureSwapChainGL(…)
Series of buffers which hold frames to be displayed
Calculates the recommended viewport size for rendering a given eye within the HMD with a given FOV cone.
Swap chain, basically double buffering

11. Initialize buffers for each eye
For each buffer in swap chain
Bind and set wrap and filter behaviour
Create a framebuffer and a depth buffer to render to
ovr_GetRenderDesc(…)
rendering parameters for the specified eye
HmdToEyeOffset (translation of given eye in meters)
Calculates the recommended viewport size for rendering a given eye within the HMD with a given FOV cone.
Swap chain, basically double buffering
Use sRGB sRGB provides an optimized use of each value of the storage range so that these values become more relevant for our eyes perception sRGB is a non-linear color space

12. Main Loop Get abs time at which the current frame should be displayed
ovr_GetPredictedDisplayTime(…)
Get predicted pose based on abs time, distance of eye from headset, etc…
trackingState = ovr_GetTrackingState(…)
ovr_GetEyePoses(…)
Prediction is used to compensate for the latency in the system
Pose corresponds to time in future when frame will be displayed
trackingState: predicted HMD pose, etc… Also contains information about hand positions

13. Pose and Position

14. Render to an Eye ovr_GetTextureSwapChainBufferGL(…)
Get current buffer from swap chain
Bind and clear that eye’s frame buffer
Calculate eye Proj * View matrix transform
Render Scene
Repeat for other eye

15. Updating Oculus ovrLayerEyeFov ovr_SubmitFrame(…)
Combines both swap chains with FOV and IPD
Can use many layers for Game, GUI, etc…
ovr_SubmitFrame(…)
Submits layer for rendering
you can use multiple layers and layer types for advanced rendering

16. Shutdown delete depth textures and framebuffers for each eye
ovr_DestroyTextureSwapChain(…) for each eye
ovr_Destroy(…) destroy session
ovr_Shutdown() shutdown sdk

17. Best Practices
Don’t affix an image in front of the user, such as a full-field splash screen
Images presented to each eye should differ only in terms of viewpoint
Consider supersampling and/or anti-aliasing

18. Best Practices
Code should run at a frame rate equal to or greater than the Rift display refresh rate
Repeated exposure to the Rift makes you less susceptible to sickness
Do not use “head bobbing” camera effects
Avoid using Euler angles

19. Resources Oculus SDK is well documented
OVR_CAPI.h, OVR_CAPI_GL.h