3D game/engine with networking. Written in C. Uses SDL3.
Video showcase - Feb 11, 2025

Cloning the project

To download the repository and SDL3 at the same time, run:

git clone --recurse-submodules [email protected]:fda0/P.Net3D.git

To download the repository and its submodules separately, run

git clone [email protected]:fda0/P.Net3D.git
git submodule update --init --recursive

Building

Project can be built on Windows using MSVC (default) or clang. Currently, only Windows is supported due to a dependency on DirectX 12. Adding Vulkan support in the future should be relatively easy, as the project uses the SDL_gpu API to handle GPU boilerplate setup.

Arguments to build script

• game - compile game target (default)
• sdl - compile SDL libraries
• msvc - compile using MSVC compiler (default)
• clang - compile using clang compiler
• release - compile with optimizations

Example commands:

# build sdl & game - with optimizations enabled
build.bat sdl game release

# build sdl & game - debug builds
build.bat sdl game

# build game - debug build
build.bat game clang

# build game using clang - debug build
build.bat game clang

Codebase

src/base

Small libraries that could be used across multiple projects.

• base_types.h - Define types and must-have-macros.
• base_arena.h - Simple & fast bump/stack-like allocator.
• base_string.h - Defines S8 - length encoded string and its helper functions.
• base_printer.h - String builder based. Tracks pre-allocated buffer and allows to easily copy text into it.
• base_math.h - Trigonometry functions, vectors, matrices, quaternions.

src/meta

meta_entry.c is compiled and ran before the game starts compiling. The plan is that all metaprogramming, code generation, and asset preparation will live there. Right now, its only job is to load .obj model files and transform them into a format expected by the engine. It can automatically generate per-vertex-normals if these are missing from the .obj file.

src/gen

Auto-generated files like models' vertex buffers or precompiled shaders go here. Automatically cleared before build. Committed using git lfs to reduce spam in change history.

src/game

The game uses the "unity build" technique to compile all .c files in one translation unit.

• game_sdl_entry.c - Entry point of the game. Initialized SDL contexts, spawns game window, poll user input.
• game_constants.h - Compile time constants used to modify how the game works.
• game_core - Manages game logic loop, initialization. Contains code that didn't fit anywhere else yet.
• game_gpu, game_render - Manages GPU setup, uploads data to GPU and dispatches render calls.
• game_render.h - Defines vertex layout, instance buffer layout. Will be built into higher level helpers that aid with putting stuff on the screen.
• game_network - Setting up connection, sending and receiving payloads over network.
• game_server / game_client - Server / client side networking logic.
• game_object - Constructors and helpers for Objects. Most things that are visible on the screen are called an Object in this engine.
• game_tick - Game physics simulation. Physics updates use a fixed timestep in this engine.
• game_key.c - Helper functions for checking user input.
• game_util - Helpers that are somewhat universal but still specific to the game - so they don't end up in src/base
• shader_* - hlsl shaders. In the future I'll try looking into systems that auto-translate shaders for hlsl & vulkan targets.

Resources

Collision

The game uses the SAT algorithm for collision detection. Two resources I found especially useful when researching its implementation:

• Collision Detection with SAT (Math for Game Developers) by pikuma
• N Tutorial A – Collision Detection and Response

Networking

Gaffer on Games articles are great to get an overview of various networking topics.

Game math

I used the Handmade Math library as a reference for matrix and quaternion math implementations.

Resources on quaternions:

• Quaternions, Double-cover, and the Rest Pose Neighborhood (2006) by Casey Muratori + video
• Understanding Slerp, Then Not Using It by Jonathan Blow