I found this incredibly interesting, I know there's a few other open source ones I see bouncing around in Phoronix forums, but this seems to be the furthest I've seen one.
https://www.furygpu.com/
New open source GPU is free to all - FuryGPU runs Quake at 60fps, supports modern Windows software
https://www.furygpu.com/
New open source GPU is free to all - FuryGPU runs Quake at 60fps, supports modern Windows software
An open source fully custom GPU has come out of stealth after four years in development. FuryGPU has been a one-man effort from games software developer Dylan Barrie, who says he put together this extremely complex hardware and software project in his spare time. FuryGPU is based on a Xilinx FPGA design, and the prototype PCIe graphics card is currently capable of achieving around 44fps in the Quake Timedemo. The work on FuryGPU was undertaken after Barrie was inspired by Ben Eater’s building a programmable 8-bit computer from scratch project.
As you can see from the pictures in this article, FuryGPU looks very much like a typical PC graphics card from about 20 years ago, modernized by equipping DisplayPort and HDMI outputs. The project is far more than the hardware, though, with Barrie admitting that the most painful aspect of this graphics card’s design was creating the Windows drivers.
Hardware, from maker board to graphics card
Barrie began realizing his dreams of building a GPU from scratch after picking up an FPGA-packing Arty Z7 development board and doing some preliminary development and testing. Subsequently, the project got a boost by the debut of Xilinx Kria System-on-Modules (SoMs), which combine “insanely cheap Zynq UltraScale+ FPGAs with a ton of DSP units and a (comparatively) massive amount of LUTs and FFs, and of particular interest, a hardened PCIe core,” enthused Barrie.