Editing Vehicle Geometry

Summary

This is a basic description of how to customize or author vehicle geometry for use in an rFactor mod.  Specifically, it is assumed you are starting with some existing vehicle geometry.

Disclaimers

• There are undoubtedly better workflows than this, but this is what we do.

• This is not a guide or tutorial for any of the tools involved.  It is assumed you are familiar enough with them to understand the features and terminology.

Tools

• Blender
• gMotor MAS utility v2.0
  
• 3DSimED
• Vehicle Viewer
  

Critical Files

• a mas file containing vehicle geometry (we'll use nsrl.mas)

• a vehicle definition file (we'll use nsrl.gnt)
• a spinner vehicle definition file (we'll use nsrl_Spinner.gnt)

Directories

To simplify the process, we'll use several dedicated directories:

• <EXTRACT>: directory for untouched MAS content
• <BLENDING>: directory for blender interaction
• <EXPORT>: directory for 3dsimed export

Process

1. Prepping for our mod

• copy nsrl.MAS to <yourshapename>.MAS
• copy nsrl.gnt to <yourshapename>.gnt
• copy nsrl_Spinner.gnt to <yourshapename>_Spinner.gnt
• edit <yourshapename>.gnt and <yourshapename>_Spinner.gnt to refer to <yourshapename>.MAS instead of nsrl.MAS.  You can also remove stuff like FIS winglets by removing them in these gnt files

2. Getting geometry into blender

• extract nsrl.mas or <yourshapename>.MAS (doesn't matter which) to <EXTRACT>
• import the GMT file (I start with the HI body file) from <EXTRACT> in 3DSimED: from the menu, select 'File -> Import Model'
  
• Export as a .3ds file in <BLENDING>: from the menu, select 'File -> Save as .3DS'
  
• import the .3ds into blender  (you can delete the default cube, camera, and light first): from the menu, select 'File -> Import -> 3D Studio'
  

3. Edit the geometry

• there will be several meshes, one for each original material
• editting seems to work better when vertices are joined, so in edit mode select all vertices and remove doubles on any particular mesh
• for the MED body file you can just reduce the poly count on the HI

4. Getting geometry back into rFactor

• export each material mesh you changed into a separate .3ds in <BLENDING>
• import the HI body GMT file from <EXTRACT> in 3DSimED
• for each material you editted:
1. delete the geometry for the material in 3DSimED: from the menu, 'Edit -> Material Operations -> Erase Material Geometry'
   
2. 'Primitives' -> 'Add Object' using the .3ds from <BLENDING>
3. replace the material (some slightly morphed new material name from the 'add') with the original material
• 'Edit' -> 'Material Operations' -> 'Replace Materials'
• first select the material you want to throw away
• then select the original material name
• the mesh should mostly look like the old most (materiallly that is)
  
4. 'Edit' -> 'Explode All Objects'
   
5. 'Edit' -> 'Normals' -> 'Smooth Vertex Normals'
   
6. 
   
• export as rFactor .GMT, with the right name, in <EXPORT> (I copy all of <EXTRACT> to <EXPORT> so I can just click on the files here to get the exact name right
• 'File' -> 'Save As rFactor .GMT' -> 'Save Model Data'
  
• Open <yourshapename>.MAS in the MAS tool
• Add the .GMT from <EXPORT>
• Save <yourshapename>.MAS

5. Testing

• for quick turnaround, the rFactor vehicle viewer is fine, but it is far too robust wrt textures than rFactor itself, so eventually you have to test in rFactor with DX7, DX8, and DX9
6. Repeat the process for any other piece of vehicle geometry (GMT files) that you want to edit (such as wings)