Cat 400

"Cat 400" (c4) is a game framework for Nim programming language.

Brief overview

"Cat 400" is a cross-platform framework designed to provide nice experience in game development. Written in nim language, it benefits from the language's elegance and expressiveness, as well as compilation to fast native code.

Core of "Cat 400" is platform-independent and may be run on every target platform supported by nim. However, default systems (which are optional) have external dependencies which may restrict their usage on some platforms.

Key features

• client-server multithreading architecture (even for single-player games) with network support
• modularity: all code is split into "systems" (video/user input/networking etc) which work independently
• systems communicate only by sending messages, thus avoiding tangled code
• ECS (entity-component-system) with custom user components support
• simple overwriting of existing systems and ability to create custom systems
• templates which include some reasonable defaults for specific game genre

So why another game framework?

I've made a research about game engines and frameworks for Nim, and none of them had solid and thoughtful design. It's super easy to display something on screen, and many people think that opportunity for a program to display cubes on screen makes it a game engine. It doesn't. When I see another game framework, I read its documentation (or code, if there are no docs at all) and try to find answers to these questions:

1. What about physics, i.e. collisions, collision shapes, force, velocity, position etc?
2. Can I do 3D graphics?
3. What if I want multiplayer over network?
4. How do I map user input to specific actions?
5. How do I occupy all cores effectively?
6. What about logging? How to debug?
7. How easy it is to create large project with thousands lines of code? How does the engine help me not get lost?

Usually many of these questions aren't covered at all, but for Cat-400 I do my best to address all of them and beyond.

Is 2D/3D supported?

Yes, 2D via SDL, 3D via SDL+Ogre3d. Also note that C4 is a framework, which means that you can use any backend for any of your systems. So, unlike game engines, you can make a 2D, 3D or even 4D (wat?!) game using any graphics library of your choice.

GUI / Game Engine

Cat 400 is not a game engine (and will never be), and everything is quite low-level - there's no gui and every aspect of game is done within source code. No level editor, too.

Feel free to create high-level tools on top of Cat 400 and share them with community if you have such an opportunity.

But where do I write code?

I know many game engines (for example, Godot) have integrated basic code editors - but they probably haven't heard about IDEs which 1) are designed for writing code, 2) already exist, are mature and just work, and 3) suit better for coding cause have extra features like plugins. So, open your favorite IDE which supports Nim and start coding a game.

But where do I edit graphics?

I know many game engines (for example, Godot) have integrated basic mesh editors - but they probably haven't heard about 3D modeling software which 1) are designed for creating 3D models, 2) already exist, are mature and just work, and 3) suit better for modeling cause have extra features like plugins. So, open your favorite 3D modeling software and start creating models.

Documentation

WARNING! Due to active development documentation is very outdated. It will be fixed once framework's API is stable.

Tutorials

Visit docs/tutorials folder - it's the best place to learn Cat 400.

Reference generation

In order to make repo clean, autogenerated reference is not included. You may generate it yourself: from repo root run

nimble genDocs

Generated reference files will be located in docs/ref folder.

Examples

All examples are available in examples folder.

You may also check templates folder. Templates are just app skeletons which contain initialization and minimal game environment, like a movable player and couple of enemies.

Submodules

Although these modules are part of Cat-400, they may be used separately in any project.

c4.entities module - entity-component system, allowing to create lightweight entities and attach any user-defined components to them, with some basic CRUD operations.

c4.messages module - Message type and any user-defined subtypes, which may be packed and unpacked using msgpack, correctly preserving type information.

c4.threads module - module for spawning named threads and sending messages between them; allows programmer to focus on his multithreaded app, not on settings up connection between threads.

Wrappers

There are several wrappers which are subpackages of "Cat-400" and may be installed and used separately, see lib folder.

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