3 ms·

Youtube channel Gamehut once mentioned that you could do 8 levels of transparency on the 3D provided you had no Gouraud shading on the quad. As such it was almo

• phire 3y ago
  That's a VDP2 effect. It can only fade the final framebuffer againt other VDP2 layers (and the skybox is implemented with VDP2 layers) After VDP1 has rendered all quads to the framebuffer (aka VDP2's "sprite data" layer), some pixels in the framebuffer layer can use an alternative color mode. Normal 3D quads (with Gouraud shading) use a 15 bit format with five bits of Red, Green and Blue representing the final color (and the the top most bit is set to one). Those background elements instead use a palletted color format. The top bit is zero (so VDP can tell which format to be used used on a per-pixel basis) and then there are 3 bits of priority (unused in this case), 3 bits of "Color calculation ratio" which Gamehut used to implement the fade, and a 9 bit color palette index. So it's not just that you can't use Gouraud shading, but these fading objects are limited to a global total of 512 unique colors which must be preloaded into VDP2's color ram (well, I guess you could swap the colors out each frame) ----- Importantly, since this trick only works against VDP2 background layers, it can't be used to blend two 3D quads against each other.