What is this called, and why is it happening?

[KommissarReb]

I'm trying to make custom buildings and playermodels, but I keep getting this weird problem in BFViewer where the textures go all crazy. Not to mention any model that had this issue like the playermodel I'm showing doesn't work in-game, whereas I was able to successfully make a usable weapon model without this problem.

COuld someone explain to me where I went wrong?

[iamastupid]

Did you remember to triangulate your model?

[Giftheck]

That's definitely an instance where you have n-gons in your model (faces with more than 4 sides). Triangulate it before exporting.

[KommissarReb]

Triangulating it fixed it! I wasn't aware that I had to do that.

Now I just need to get the model to move properly instead of staying in a T-pose when standing idle, moving, shooting, etc. I'm following Sereja's tutorial here, but I'm stuck at the part under 3.) "Animation Template Merging" where he says to click Polygon and crop the stormtrooper model (I'm assuming he was referring to "override_texture" and not "sv_snowtrooper"). I take it there are no video tutorials on how to do this?