what is d4 fr?

D4 is a 3D graphics program that draws objects on your screen by converting 3D models into 2D images, a process called rasterization. Instead of using a graphics card (GPU), it does all the work on your regular computer processor (CPU), making it simple to understand and tinker with. It's designed as a learning tool rather than something you'd use for serious work. The project includes two interactive demos that let you load and explore 3D models. You can drag and drop model files onto the program, or use command-line options to control it. Once loaded, you can rotate and move around the model using your keyboard, WSAD keys for movement and arrow keys for rotation, plus some extra controls mapped to nearby keys. The program renders the 3D scene in real-time as you interact with it. Someone learning computer graphics or wanting to understand how 3D graphics work from the ground up would find this useful. It's small and readable enough to study the actual code and see how shapes get transformed into pixels on screen. A hobbyist interested in the D programming language might also use it as an example project. However, this isn't meant for production use or handling complex modern 3D models, it's purely for education and experimentation. The project is written in D, a programming language designed to be practical and efficient while staying readable. It relies on a few established libraries for the heavy lifting: Assimp for loading 3D model files, DevIL for image handling, SDL for window management, and Derelict as a binding layer. The README points to an external website for more details, and the code itself is open source under the GPLv3 license.