updated readme

Readme.md

@@ -1,6 +1,108 @@
-This projects goal is to provide Rift bindings for Rust.
+VR-RS
+=====
 
-Right now it is none functional, only grabbing a few pointers from the framework.
+[![Build Status](https://travis-ci.org/csherratt/vr-rs.svg?branch=master)](https://travis-ci.org/csherratt/vr-rs)
 
-libovr.a is not supplied with this library for legal reasons. You may obtain a copy from
-https://developer.oculusvr.com/ .
+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
+
+```rust
+
+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
+
+```rust
+// 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.
+
+```rust
+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](http://static.oculusvr.com/sdk-downloads/documents/Oculus_SDK_Overview.pdf#subsection.5.5).