VR-RS

VR-RS providers bindings for the Oculus's libovr. Currently it only provides bindings for 0.2.5c.

Building

Make sure all submodules were cloned first.

git submodule update --init --recursive

Building is straight forward.

./configure
make

Using VR-RS

Initializing

extern crate ovr = "oculus-vr";

fn main() {
    // initialize the library
    ovr::init();

    // create a device manager context
    let dm = match ovr::DeviceManager::new() {
        Some(dm) => dm,
        None => {
            println!("Could not initialize Oculus Device Manager");
            return;
        }
    };

    // create hmd instance
    let hmd = match dm.enumerate() {
        Some(d) => d,
        None => {
            println!("Could not enumerate Oculus HMD.");
            println!("Was it unplugged?");
            return;
        }
    };

    // create a sensor fusion, this is used to gather sensor readings
    let sensor_fusion = match ovr::SensorFusion::new() {
        Some(sf) => sf,
        None => {
            println!("Could not allocate Sensor Fusion")
            return;
        }
    };

    // get a sensor device from the hmd.
    let sensor = match hmd.get_sensor() {
        Some(sensor) => sensor,
        None => {
            println!("Could not get the sensor from HMD");
            return;
        }
    };

    // when new sensor readings are ready they will automatically
    // update the sensor fusions state
    sensor_fusion.attach_to_sensor(&sensor);

    let hmd_info = hmd.get_info();
}

Getting head tracking results

// return a Quaternion of the predicted head's position
let orientation = sensor_fusion.get_predicted_orientation(None);

The orientation can be applied to your view matrix create a new view matrix that accurately tracks the position of the head.

Rendering the HMD barrel distortion.

vr-rs includes the shader and some utilities that can help create the barrel distortion.

First you must render an undistorted scene into a texture. vr-rs supplies a utility function create_reference_matrices that can be used to create the view / projection matrices.

let ((projection_left, projection_right),
     (view_left, view_right)) = ovr::create_reference_matrices(&hmd_info, &view_matrix_base, scale);

view_matrix_base is the view matrix created by applying the head tracking with any other orientation or positions required to move the camera.

scale is the scaled size of the texture compared to the hmd native resolution. 1. is a good starting point.

The best resource to drawing the barrel distortion is going to be the Oculus VR pdf.