The 3D for PiStorm project, spearheaded by Steffen Haeuser and with technical development led by Dennis, continues to progress with the aim of equipping the Amiga Equipped with PiStorm (Pi 4 or CM4) and a 3D library that can be used by compatible games and software. After a prolonged period without updates, the latest update confirms significant progress despite the technical challenges encountered.
Unlike the Raspberry Pi 4's GPU, the VideoCore VI graphics chip lacks complete official documentation. Although there is plenty of example code, especially from the Gallium3D project, its complexity necessitates unraveling its inner workings through experimentation. This has limited the pace of development.
The team expects to have a first working example available in a few weeks. It won't yet be a complete library, but rather a technical test capable of generating binning and rendering lists, compiling GPU code into shaders, and displaying a basic result on screen—likely a colored triangle. Reaching this milestone would confirm that the rendering chain is working correctly.
Among the main obstacles overcome are differences in memory organization between VideoCore generations, changes in the operation of the MMU, since VC6 uses physical addresses instead of bus addresses, and problems arising from endianness compared to the big-endian system of the Amiga and complications related to the QPU assembler used for shaders.
In its current state, the 3D driver generates pseudocode that is translated into instructions executable by the GPU, and driver initialization is already implemented—a particularly complex process due to the lack of documentation. The developer is exploring ways to simplify the compilation flow to adapt it to a single hardware configuration, which could reduce complexity and improve performance.
Currently, work is focused on the binning lists, for which the code for the example is about 90% complete. Once these are finished, the implementation of the rendering lists will be addressed. If no new complications arise, this first working example could be ready in a few weeks, marking a decisive step towards modern 3D acceleration in systems. Amiga equipped with PiStorm.
