A deep dive into why additive blending effects looked worse on the Nintendo 64 than on the PlayStation, and how to work around the N64 RDP's lack of color clamping. The N64's RDP wraps around instead of clamping blended colors, causing visual artifacts. The solution involves rendering to a 32-bit RGBA buffer at 1/8th intensity using the fog alpha trick, then converting back to a 16-bit framebuffer using optimized RSP vector microcode (written in RSPL, a C-like language that compiles to MIPS). The RSP conversion runs in ~3.1ms for a 320×240 frame, making the technique practical despite the N64's limited memory bandwidth.
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