Gama: A Simple C Game Engine

Gama is a lightweight, cross-platform game engine written in C, designed with simplicity and education in mind. It aims to provide a convenient and powerful way for students and beginners to create 2D games(and some real-time graphical applications) while learning the fundamentals of C programming. The engine prioritizes a minimal, clean C API, control over the game loop, and a stack-first memory philosophy.

Philosophy

Gama is built on a few core principles to make game development in C more approachable and fun:

• You Have Control: Gama gives you, the developer, full control over the main game loop. The engine provides utilities but stays out of your way.
• Stack First, Heap Less: The API encourages using stack-allocated data structures to leverage C's automatic memory management and reduce the cognitive load of malloc and free.
• No Global State: Gama is designed to avoid global state. You can structure your game into different scenes (as simple C functions), each with its own initialization, objects, and cleanup.
• Immediate Mode: The 2D rendering API follows an immediate-mode paradigm. You draw shapes directly each frame, which simplifies state management and is perfect for learning.

Features

Core Engine

• Cross-Platform: Build and run your games on Linux, Windows, and the Web (via WebAssembly). Gama foundations in C make even more different domains available, but that's additional work to be done as needed
• Simple C API: A clean, beginner-friendly C99 API.
• Full Game Loop Control: You own the main loop.
• Custom Memory Allocator: A static-pool-based malloc implementation, ideal for controlled memory environments like WASM.
• Lightweight: gama installation is less than 400MB on windows(with zig and tcc toolchains), and less than 50MB on linux(relying on system packages).

Rendering

• 2D Immediate-Mode Graphics: Simple functions to draw primitive shapes like rectangles, circles, lines, and triangles.
• 2D Sprite Animation: A complete sprite system with support for sprite sheets and custom animation sequences.
• 3D Software Rasterizer: A built-in 3D rendering pipeline that projects 3D models onto a 2D image buffer, complete with lighting and backface culling.
• 3D Model Loading: Support for loading .obj and .gltf 3D models.
• Material & Texture Support: The 3D pipeline supports basic material properties (diffuse color, shininess) and will use the average color of a texture if one is provided.

Physics

• Built-in 2D Physics Engine: A simple physics simulation for your 2D games.
• Collision Detection: Supports Circle-vs-Circle, Rectangle-vs-Rectangle, and Circle-vs-Rectangle collision detection.
• Physics Bodies: Create bodies with properties like mass, velocity, acceleration, and restitution (bounciness).
• Physics System: Manage groups of bodies, apply global forces like gravity, and handle collisions automatically.

UI & Widgets

• Immediate-Mode UI: A suite of skinnable, immediate-mode UI widgets.
• Available Widgets:
  • gmw_button: An interactive button.
  • gmw_switch: A toggle switch.
  • gmw_scale: A slider for selecting a value in a range.
  • gmw_joystick: A virtual joystick for on-screen controls.
  • gmw_frame: A panel for grouping UI elements.
• Theming System: A simple system for saving and restoring widget themes to easily change UI styles.

Compiler Toolchain

• Zero-Setup on Windows: On Windows, Gama comes bundled with pre-configured TCC and Zig compilers. No external downloads or PATH configuration needed.
• System-Native on Linux: On Linux, Gama relies on tcc and zig from your system's package manager, ensuring seamless integration.
• gama dev for Rapid Development: Use gama dev to instantly run your project with the fast TCC compiler. This command also features hot-reloading for rapid iteration.
• gama build for Optimization: When ready to create a release build, gama build uses the more powerful and optimizing Zig CC compiler.
• Direct Compiler Access: Gama provides proxy commands to access the underlying compilers directly, which is great for educational purposes or advanced build scripting. You can use gama tcc, gama zig, and gama zcc as direct replacements for the real commands.

And More...

• Animation Utilities: A collection of easing functions (spring, ease-in, ease-out) for smooth animations.
• Input Handling: Straightforward functions for checking keyboard and mouse state.
• Math & Debug Libraries: A custom math library and simple print-based debugging macros.

Architecture Overview

Gama's cross-platform power comes from its flexible backend architecture.

• libvgama: The native heart of the engine. Written in V, libvgama runs a sokol-based game loop, providing a fast and efficient rendering backend via gg.
• gama.js: The web backend. This TypeScript runner uses a Web Worker and SharedArrayBuffer to run your C code (compiled to WASM) off the main thread for maximum performance in the browser.

Getting Started

Getting started with Gama is designed to be as simple as possible.

1. Download and Install:

   • Windows: Download and run the latest gama-*-windows-setup.exe from the releases page. The installer handles everything for you.
   • Linux: Download the .deb or .pkg.tar.zst package and install it with your system's package manager. Make sure you also have tcc and zig installed (sudo apt install tcc zig or sudo pacman -S tcc zig).

2. Create a New Project: Open a terminal and run:

   gama new my_first_game
   

3. Run in Development Mode: Navigate into your new project and start the development server:

   cd my_first_game
   gama dev
   

   Your game window will appear, and the code will automatically re-compile and re-run whenever you save a change.

4. Build for the Web: To compile your project for a web browser, run:

   gama build web
   

   This will create a build/web directory containing all the files needed to run your game on a local web server.

Development with Gama

Here is a simple example of a "Hello, World" application in Gama to demonstrate the basic structure.

#include <gama.h>

int main() {
  // Initialize the engine and create a 600x400 window
  gm_init(600, 400, "Hello Gama!");

  // Set a background color
  gm_background(GM_DARKSLATEGRAY);

  // Main game loop
  while (gm_yield()) {
    // gm_yield() handles events, clears the screen, and returns
    // true as long as the window is open.

    // Draw a red rectangle in the center of the screen
    gm_draw_rectangle(0, 0, 0.5, 0.3, GM_RED);

    // Draw some text
    gm_draw_text(0, 0, "Hello, World!", "default-ui", 0.1, GM_WHITE);
  }

  // The engine will automatically handle cleanup on exit.
  return 0;
}

Development on Gama

Prerequisites

• V Compiler: The mng build script is written in V. You will need to install the V compiler from vlang.io.
• A C Compiler: For building vlibvgama (e.g., clang or gcc).
• bun: For building gama.js.
• unzip: The mng script uses unzip to set up the Zig toolchain for packaging.
• Doxygen (Optional): For generating reference documentation.
• makensis (Optional): For building the Windows installer.
• nfpm (Optional): For creating .deb packages.

Building and Running

The project uses two primary scripts for development and packaging, both located at the project root.

• ./mng: This is a task runner written in V, used for most common development operations. It allows you to build individual components of the Gama ecosystem.

  • ./mng build: Compiles the gama CLI tool for all target platforms.
  • ./mng runner native: Builds the libvgama native library.
  • ./mng runner web: Builds the gama.js web runner.
  • ./mng get-zig: Downloads and sets up the Zig compiler needed for packaging.
  • ./mng package: Creates the final distributable packages (.deb, .tar.zst, .exe installer).

• ./all: This is a simple shell script that runs the entire build and packaging pipeline from start to finish. It's the easiest way to ensure all components are up-to-date and generate a full release.

Project Structure

• lib/gama/: Contains all the core C header files for the engine's modules (3D, physics, widgets, etc.).
• gama/: Vlang source code for the main gama CLI tool and build logic.
• gama.js/: TypeScript source for the WebAssembly frontend and JS/C interop.
• mng: The main V script used for building, packaging, and managing the project.
• all: The master shell script to build and package everything.
• runners/: Contains the platform-specific code for running Gama applications (e.g., on web or native).
• site/: SvelteKit source code for the official website and documentation portal.
• test/: Contains example projects and test cases for the engine.

Contributing

Contributions are welcome! Please feel free to submit a pull request or open an issue.

To contribute to the website or documentation:

• The website source code is in the site/ directory.
• The API reference is generated automatically with Doxygen via the ./mng docs command.

License

This project is licensed under the MIT License - see the LICENSE file for details.