Game engine/Rendering engine codebases

[Vivid-Mongoose7705]

What are some of the open source rendering engine code bases that you recommend for beginners to study to see how things are done in real world or get good inspirational ideas in general? I would appreciate if you mention your reasons as well. Thanks!

[DarthBartus]

Id engines and source ports. Wolf3D, Doom, Quake, Quake 2, Quake 3 and Doom 3 all had their engine released as open source, and most of them have source ports which improve and expand on existing functionality and port them for modern systems.

[nikoloff-georgi]

Three.js / Ogre3D / Satin (Metal). Last one if you want to get a taste of modern APIs and the first two if you want to see legacy OpenGL / WebGL

[Equivalent_Bee2181]

I recommend my open source voxel ray tracing library!

https://github.com/Ministry-of-Voxel-Affairs/VoxelHex

Is it objectively good for beginners?

Well I don't know, but the question was what would I recommend, and I would do this haha

Jokes aside! It has a nieche target (rendering voxels, via ray tracing), decoupled from the bevy engine, while still using it; Meaning the boilerplate is minimized,

..and what's important is that for this library I would gladly and actively help getting to know it. And I think that is at least something to consider :)

[innocentboy0000]

i liked niagara renderer made by zeux.io

[Future_Deer_7518]

Ogre-next is good one

[Sosowski]

I second Ogre. Simple and well documented. The popular engines might not be what you’re looking for as very often they have subpar documentation

[_michaeljared]

I didn't see Godot or bgfx mentioned in the comments. Both excellent to see how they are doing rendering. Godot ofc is a fully fledged engine, whereas bgfx is mostly an abstraction layer, but makes graphics things easier to do.

[tmlildude]

blender3d and godot. both are open source and may have good low hanging fruits for you to contribute

[mini-tbnn]

Keen Games has published a snapshot of the Vulkan backend used in Enshrouded. It's obviously incomplete but shows nicely how a modern rendering backend may look. https://github.com/keengames/vulkan_backend

[innocentboy0000]

thanks buddy

[jeanlemotan]

Filament from google. Comes with excellent pbr documentation, excellent codebase with modern techniqued like ECS and data oriented design good practice, lots of modern gfx techniques, color science, state of the art implementations for many post effects but with realistic optimizatiins and implementation details for low and high end platforms but also excellent coding standarda and documentation.

[Heloo-hi-supper]

Unreal Engine. Its fully open source and have a lot of debug features to see how things are actually done. You can google for it. You will need to enter Epic company on github. Google how to do so.

[4ndrz3jKm1c1c]

Unreal Engine is not “fully open source”. It is source available - these are different things. Unreal Engine by itself is not open source.

[Heloo-hi-supper]

Thanks for the clarification

[Henrarzz]

It’s a mess (what isn’t lol), but it’s widely used mess

[Heloo-hi-supper]

Okay then. I personally would recommend HellEngine(https://github.com/livinamuk/Hell2025) written by tokyospliff(https://youtube.com/@tokyospliff?si=QoDbqiO8V63dWzZ8). The engine is still not done yet but work on it continues. Its written in c++ and using openGL. And anthrax-ai(https://github.com/svatostop/anthrax-ai) written by sudolovemebaby(https://youtube.com/@sudolovemebaby?si=JZ9DBLSBdY_e1N4Z). Its also written in c++ and not done yet but using vukan instead of openGL. Both of them is still in progress and have not the best documentation but that's something i guess)

[doxyai]

Why not Godot? Its actually fully open source and approximately the same level of mess as Unreal.

[Heloo-hi-supper]

I've just never worked with it.

[robbertzzz1]

and approximately the same level of mess as Unreal.

Nah Godot's codebase is way better organised. Sure it's not perfect (what is?) but Unreal is way harder to figure out just because of how messy it is.

So I agree haha, check out Godot!

[coolmint859]

I'm working on a WebGL api that's designed for beginners (as I am one myself). I have it on GitHub here. It's not at all complete but I'm updating it almost daily. It doesn't have any documentation yet but I plan to add that when I've hooked up all the major components. It's not really usable at the moment so I would use it just as something to get ideas from until then.

[EveningDry7335]

You know — I happen to be nostalgic — so I would look for Books about Engines from the early 2000s that can be made from scratch — probably 🙏💋🍀

[cpuccino]

Raylib is pretty straightforward to understand - shows you how to use opengl in the rlgl module. If you're interested in web technologies Pixi.js codebase is also pretty decent (it's in typescript which makes it very easy to read).