I'm a beginner in game development and game programming. I have experience in computer graphics - mainly OpenGL In those days Finally, I have some spare time to polish my game coding skills. But when coming to program a simple 3d game, I couldn't find any good resource for free textures and models for 3d graphics (for 2d game for example, I found many resources for sprite sheets and so on).
Is there any good resource you're familiar with for 3d game textures/models?
The Blender foundation has a large model repository which may be of use.
This is not a programming queston.
As far as I know, good, free and high-quality modeling resources does not exist (from "good", "free" and "high-quality", select two). There are multiple free model repositories, but quality of content is generally poor, and there are few places where you can buy models.
There are free textures in multiple places (like this one), and they are easier to find than good free models.
Also, most of free content frequently includes some kind of catch - "non-commercial use only", "creative commons share alike"(i.e. if you make derivative, it should use same license), or it is under GPL.
Anyway, if you're okay with "Creative Commons share alike" and GPL, then you can probably use content from some of opensource games (OpenArena ), and get quite a lot of textures from wikipedia or wikimedia commons, flickr, and you can google for "free textures". You should be careful about using content from opensource games - some opensource projects (like war$ow and sauerbraten) use closed-source/restricted licenses for game content (i.e. you're free to reuse modify engine, but you cannot modify game content and you cannot use it with modified engine. Reasons are pretty obvious).
Anyway, it depends on what kind of model you want. It is pretty easy to find "easy" stuff like boxes, barrels, etc, because everyone can do that. When it comes to guns and vehicles, there will be a trouble - quality will drop, and number of good models will decrease. And if you want a fully rigged animated character with multiple animation, normally you can forget about it - such content is almost impossible to find. But you can probably use mods for Q3 and Q2 if you want characters (you can forget about physics in this case, though)
I'd recommend to forget about "free stuff", and try to make content yourself or hire someone to do that.
If you decide to make content yourself, then you'll need digital photo camera and (optionally) graphic tablet. You can make mediocre textures from photos (digital camera is cheap) using gimp, gimp-resynthesizer plugin, gimp-texturisze plugin, high-pass filters, etc. You can also make normal maps using blender or gimp, and there are even tutorials about extracting them from photos (you still will need to process them by hand). Modeling and animation can be done in blender (after 1 or two weeks of training) using reference photos. Low poly modeling is pretty quick (20 minutes to make a low-poly low-quality gun, hour or two to make simple character), but texture and animation will take more (setting up animation for character can take a few hours for amateur, making one animation for character will take at least several hours as well, making texture unwrap - hour, painting texture - up to few days, depending on quality you want, available reference material, availability of graphic tablet, etc). It is possible to cut corners a bit - for example, for making animations, you can film motion using photo camera(or video camera), and then use it for rotoscoping. Also, you'll need to find some kind of model format blender can export to, or you'll have to write an export plugin in python.
There are some free models at Turbosquid that I use sometimes for my XNA games. But of course, the best stuff is not free.
My experience is that there is very little in the way of quality 3d models with animation and full rigging freely available. There a few companies like this who sell suitable models cheaply and I guess most hobbyists could afford one or two models from them fairly easily which would probably be sufficient for learning. (I have no connection to them but I did buy one model pack from them which I quite liked)
It would be nice if there were a few more generally freely available 3d animated models around though. I even think it might be in the interests of some of the companies that make them to give a few away. If I'd been able to get further in my hobby projects I might have spent £100-200 in total on some nice model packs to make my project better, but due to the lack of any real 3d animated models I ended up losing interest in all my 3d projects before I got to the point of thinking maybe I'd spend a little money on this hobby. I wonder if the availability of a few more free quality models would actually significantly increase the size of the market for those companies as more people got their projects to the point where they were willing to spend a little money on it.
Some company should make a nice model pack with a few static models and a couple of fully rigged and animated humans and "monsters" and say that if the community donates £10000 they'll release them for free use. I suspect there are enough people out there who would like a few quality models they might reach this target in the same way that Blender was originally sold to the public.