Building an FPGA 3dfx Voodoo with Modern RTL Tools

The author built an FPGA reimplementation of the 3dfx Voodoo 1 GPU using SpinalHDL, finding that the main challenge was not rendering triangles but precisely matching the original hardware's fixed-function behavior. The post focuses on two key abstractions: representing the Voodoo's register semantics in SpinalHDL and debugging the graphics pipeline using netlist-aware waveform queries in conetrace. Despite having no programmable shaders, the Voodoo's complexity stems from its numerous hardwired rendering behaviors including Gouraud shading, texture filtering, depth testing, and fog.