Uniview Mod File Conversion

As an example on the Tesla in space module

1. Starting with tesla.mod file

2. Creating tesla.asset 1. Specifying local files we later need. By specifying with resource, we put them in the same folder as the asset file and don’t need to put them on a server anywhere

   local kernel = asset.resource("tesla.bsp")
   local model = asset.resource("tesla.obj")
   local texture = asset.resource("white.jpg")
   

3. Converting

```text
coord
{
  name tesla
  parent SolarSystem

  unit 1000000.0
  unitname 1000 Km
  entrydist 10
  positionfile modules/tesla/teslapos.conf
  orbitfile modules/tesla/teslaorbit.conf
  positionhook tesla
}
```
1. `teslapos.conf` mentions the spice information which is converted into
1. `teslaOrbit.conf` contains information about the orbit
1. First we create a coordinate system for the Tesla (this can be merged with the model as well)
1. Then a *Trail object. In this case, because we have a start and end time, we use a `RenderableTrailTrajectory` rather than `RenderableTrailOrbit`
   ```lua
   local TeslaPosition = {
     -- Name is arbitrary
     Name = "Tesla Position",
     -- Parent uses the asset.require to retrieve the name from another asset file
     Parent = transforms.SolarSystemBarycenter.Name,
     -- Values for this come from the original file
     Transform = {
       Translation = {
         Type = "SpiceTranslation",
         Target = "-143205",
         Observer = "SUN",
         Kernels = kernel
       }
     },
     -- GuiPath is an arbitrary string that is only used in the user interface to build a tree
     GuiPath = "/Solar System/Tesla"
   }

   local TeslaTrail = {
     Name = "Tesla Trail",
     Parent = transforms.SolarSystemBarycenter.Name,
     Renderable = {
      Type = "RenderableTrailTrajectory",
       Translation = {
         Type = "SpiceTranslation",
         Target = "-143205",
         Observer = "SUN",
         Kernels = kernel
       },
       Color = { 1.0, 0.6, 0.2 },
       StartTime = "2018 02 07 02:46:00",
       EndTime = "2030 01 01 23:59:59",
       SampleInterval = 60 * 60 * 24 -- One sample every day
     },
     GuiPath = "/Solar System/Tesla"
   }
   ```
  1. Ignoring (not sure why it is needed for Uniview
     ```text
     coord
     {
      name teslasmC
      parent tesla

      unit 1.0
      unitname 1 m
      entrydist 500

     }
     ```
  1. Converting
     ```text
     object tesla sgOrbitalObject
     {
       coord teslasmC
       geometry SG_USES teslaMesh.conf

       cameraradius 0.40
       targetradius 140
       scale 0.33
       lsize 1000000
       align earth 1 0 0

       off

       guiName /Solar System/Satellites/Tesla
     }
     ```
     into
     ```lua
     local TeslaModel = {
       Name = "Tesla",
       Parent = TeslaPosition.Name,
       Renderable = {
         Type = "RenderableModel",
         Geometry = {
           Type = "MultiModelGeometry",
           GeometryFile = model
         },
         ColorTexture = texture
       },
       GuiPath = "/Solar System/Tesla"
     }
     ```
     Unfortunately, we don't support multiple textures or MTL files yet (or at least I don't know how to use the latter), so we have to use a pure white texture.
  1. Exporting assets to the outside world:
     ```lua
     local objects = { TeslaPosition, TeslaTrail, TeslaModel }
     assetHelper.registerSceneGraphNodesAndExport(asset, objects)
     ```