Windows XP’s glossy chrome cost a GPU with acceleration. We wanted it on a Pentium II with VESA and 4 MB of VRAM, drawn entirely in software. The solution is three counterintuitive decisions, all born from the same question: what can this machine actually afford?
Decision 1: always compose in 32 bits
Everything draws into ONE 32-bit XRGB back buffer in system RAM. It sounds ruinously expensive for the era and it is the opposite: the drawing code is format-independent and there is no dithering anywhere. Gradients, bevels and shadows are computed once, clean. Only the present() step converts to the hardware’s real format.
Decision 2: a palette you never search
At 8bpp we use a 3-3-2 palette: three bits of red, three of green, two of blue. Converting a 32-bit pixel is a shift and a mask — zero table lookups, zero «nearest color»: it is the three lines of gfx_pack_index_332(). At 16bpp, straight RGB565. And only dirty rectangles get converted: a click repaints a window, not a screen.
There is no per-pixel alpha in the whole system. Icons use a magenta color key; shadows are a cheap read-modify-write on the edge strips.
Decision 3: ban alpha
Per-pixel transparency is the luxury a period machine cannot afford. So it does not exist: icons and cursors use a 1-bit magenta color key, and window shadows are a cheap darkening of the edge strips. The eye is fooled exactly the same, and it fits the budget. 457 host checks, run under both gcc and clang on every push, make sure no commit breaks the conversion.
D. ABELLÁN · FOUNDER · PRINCETON, IL · 2026.04.22