[nickmqb]

VGA is an analog protocol, but the FPGA can only output a 0 (GND) or 1 (3.3v) on its I/O pins. I'm using a Digilent VGA Pmod [1] which uses a set of resistor ladders to map each color component from a 4-bit value to an analog voltage that goes to the monitor. This means that we have 14 pins: R (4x), G (4x), B (4x), HS (1x) and VS (1x).

[1] https://store.digilentinc.com/pmod-vga-video-graphics-array/

[mysterydip]

Oh duh, I should've remembered that. So 12 bit VGA then. From the demo that seems sufficient. Have you tried getting rid of the LSB to see if there's a noticeable difference? I'm curious how few colors you actually need

[nickmqb]

Most textures look fine despite the 4-bit quantization, but color artifacts/hue change do become more apparent when multiplying with a light factor (to darken the textures on the bottom and sides of blocks), so I'd say 4-bit is definitely pushing the limit. 6 bits or even 8 bits per color component would be ideal, though unfortunately on a small FPGA like this we cannot afford such luxuries ;). It is probably the first thing I'd change if I were to port this to a larger FPGA, since it would be pretty straightforward to do and the increase in visual quality would likely be worth it.