The Valve Source engine has its own model format, MDL. Valve MDL files are created with Valve StudioMDL, which compiles SMD and QC files into MDL.
What is a QC?
A QC file is a language used to define how a 3D model should be processed by StudioMDL. This is an example QC file:
$modelname "props_sdk/myfirstmodel.mdl"
$body mybody "myfirstmodel-ref"
$surfaceprop combine_metal
$cdmaterials "models/props_sdk"
$sequence idle "myfirstmodel-ref" // no animation wanted, so re-using the reference mesh
$collisionmodel "myfirstmodel-phys" { $concave } // can be omitted if no collision is neededThis file is processed by StudioMDL to create the MDL file from the SMD.
SMD?
SMD is a file format exported from 3D software, for example Blender or Maya. This can’t be processed by Source itself, so it is compiled into a MDL. This adds the materials, the physics, sequences, etc.
You can also use the Valve Face Poser to create sequences.
What’s wrong with this?
This is a PAIN. You have to track thousands of QC and SMD files in Git, and keep them maintained. If you mess up in your QC, thats half an hour of debugging, to find you forgot a ”$” or something.
My plan is to mod the Source engine to support gLTF files, so I don’t have the mess of QC, SMD and MDL files.
Modding the Source engine for gLTF
I have no idea how I am going to do this. Considering the engine currently only knows how to read MDL files, we can inject gLTF data maybe?
I’ll keep you updated on my plans.