Handle parameters over MAVLink and document their usage

README.md

@@ -5,6 +5,41 @@ The project is configured to display cockpit instruments with [lidia](https://py
 
 Named in this order so not everything starts with the same word.
 
+## Usage
+
+The application will attempt to start in VR, but if it fails it will display the default pilot viewpoint looking forward.
+
+### Parameters
+
+These can be modified over MAVLink, for example using MARSH Manager.
+
+Example changes to `NAV_OFS_` parameters to start in given positions:
+
+- Sidestep, vertical repositioning: all default
+- Accelerate/decelerate: `HDG` = -90
+- Hover maneuver: `X` = 50, `Y` = 50
+- Start of slalom: `HDG` = -90, `X` = -100, `Y` = 300
+
+#### NAV_OFS_HDG
+
+Displayed heading relative to default position, in degrees.
+
+#### NAV_OFS_X
+
+Starting position offset, forward in default orientation, in meters.
+
+#### NAV_OFS_X
+
+Starting position offset, right in default orientation, in meters.
+
+#### LOCAL_FRAME_LAT
+
+Latitude of local coordinate frame origin when using messages with global position, in degrees.
+
+#### LOCAL_FRAME_LON
+
+Longitude of local coordinate frame origin when using messages with global position, in degrees.
+
 ## Development
 
 The asset files like textures and models are very big, so the project also uses [Git Large File Storage](https://git-lfs.com/).
@@ -77,13 +112,3 @@ scons platform=windows use_mingw=yes use_llvm=yes
 - Reduce pixel artifacts
   - Adjust antialiasing
   - Ensure there are mipmaps and they're used
-- Increase sense of urgency/stress when tracking the visual height cue
-  - Change the perspective to make the ball leave the strip for smaller error
-  - Time to complete the task
-    - Configurable length
-    - Some way to verify completion
-    - Some way to reset it
-    - Sound cue for desired and required timing
-    - Visual timing like progress bar
-      - Also change color
-      - On the vertical cue or instrument panel?