cog

Warning

UNDER ACTIVE DEVELOPMENT: This library is currently in an experimental stage. The API is subject to frequent and breaking changes. It is not recommended for use in production projects at this time.

cog is a portable, single-header graphics library written in C. It provides a straightforward API for window creation, OpenGL context management, texture handling, and hardware-accelerated rendering. The library goal is to give a single file to drop into your project and provide a hassle-free foundation for building graphical applications, tools, and games without the burden of complex build systems or heavy dependencies.

Features

• Single-Header Design: Drop cog.h into your project to start using it.
• Batch Rendering: Automatically batches draw calls for primitives (rectangles, circles) and textures to maximize GPU performance.
• Texture Management: Built-in image loading and texture handling using stb_image.h.
• Platform Support: Currently targets Windows natively (using GDI32 for windowing and OpenGL32 for rendering). No heavy external frameworks required.

Integration

To use cog in your project, download cog.h on releases page.

In exactly one C or C++ file, define COG_IMPLEMENTATION before including the header to compile the underlying implementation:

#define COG_IMPLEMENTATION
#include "cog.h"

In all other files where you need to access the library, simply include the header normally:

#include "cog.h"

Quick Start

Here is a minimal example demonstrating how to initialize a window, draw shapes, and manage the render loop.

#define COG_IMPLEMENTATION
#include "cog.h"

int main(void) {
    // Initialize window and rendering context
    cog_window* window = cog_create_window("cog Application", 800, 600);
    
    // Main application loop
    while (!cog_window_should_close(window)) {
        cog_poll_events();
        
        // Clear the screen (assuming a clear function exists in your API)
        cog_clear_background((cog_color){ 0, 0, 0, 255 });

        // Queue rendering operations
        cog_draw_rectangle(window, 100, 100, 200, 150, (cog_color){ 255, 0, 0, 255 });

        // Flush the batch array to the GPU and swap buffers
        cog_render(window);
    }

    cog_destroy_window(window);
    return 0;
}

Compilation

When compiling an application that uses cog on Windows, link against the standard OpenGL and GDI libraries:

gcc main.c -lopengl32 -lgdi32

Development

If you are modifying the library itself, this repository uses just as a command runner.

Generating the Release Header

The library development files are located in src/. To bundle them into the distributable single-header format, run the packaging script:

just

or

just build-release

This executes scripts/embed.py, which generates release/cog.h.

Running Examples

Examples are located in the examples/ directory.

Compile and run a specific example file (e.g., examples/textures.c):

just run-example textures

Clean the build output:

just clean

License

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