I love this engine. Question about MDR models

[noire-dev]

How to use the MDR or IQM format for character models, is it a skeletal format?
There is a question about model culling, where it is located on the client side, and is it possible to make the collision not a box but a more complex one, I need this for Danil's Mod sandbox on the Quake 3 engine

[ensiform]

Models are not used for collision in this engine, you would need to write all of that yourself.

[ghost]

Both are skeletal format. Personally I recommend IQM over MDR (higher FPS + lower size). IQM works best with GPU vertex skinning (needs Opengl2 renderer).
Anyways, the person of interest is zturtleman, he can also explain how to rework things in the cgame module to set up IQM models. He didn't only implement the IQM format, he also works on a really cool model creation tool called Maverick Model 3D (with IQM support).
If you have Discard installed you can talk to him there.
I recommend to get in contact with him, because in the past I had the same question(s) like you, and he helped me really a lot.
Here is a link to a very technical but interesting conversation I had with him:
https://discourse.ioquake.org/t/current-status-of-iqm-md5-models/1153
Where you can find zturtleman:
https://github.com/zturtleman
https://twitter.com/zturtleman
https://clover.moe/

Basically he did most model imrovements MDR/MDS/IQM for his Spearmint engine, which is based on ioquake3. So all his work will most likely apply to Q3e as well.
I really hope you will success using those model formats. Good luck!