direct_color — the pixel byte IS the color

Screenshot

Effects arc 4/7. Direct color mode (CGWSEL bit 0, exposed as colorMathSetDirectColor()) makes the PPU read 8bpp BG pixels as BBGGGRRR colors directly, bypassing CGRAM entirely. This example builds a 16×16 chart of all 256 pixel codes procedurally — zero assets, 256 solid-color tiles generated in C at init — and loads a deliberately different CGRAM palette (a grayscale ramp), so A flips the very same VRAM bytes between two readings: the BBGGGRRR color cube (direct, boot state) and the grayscale ramp (CGRAM). Nothing is re-uploaded on toggle — one register bit changes the meaning of every pixel on screen.

ROM mode: LoROM (project default).

SNES Concepts

• Direct color (CGWSEL bit 0): 8bpp pixel value → 15-bit BGR by field expansion (B: 2 bits, G: 3, R: 3); tilemap palette bits become one extra low bit per channel (2048 colors max, no CGRAM cost)
• Applies to 8bpp layers only (BG1 in modes 3/4, Mode 7) — 2/4bpp layers and sprites keep their CGRAM palettes untouched
• Mode 3 and the 8bpp planar tile format (4 interleaved bitplane pairs, 64 bytes/tile), built byte by byte in C
• The colormath module's CGWSEL shadow: the setter composes with any blending configuration

How to Build

make

Modules Used

console, dma, background, colormath, input