But these games seem to fit what I think you are saying by the Saturn needing to use unlit large 16-bit textures if rendering direct RGB.
Up until now, in any discussion about the Saturn, everybody would balk at the idea of the Saturn even being capable of 8-bit textures. For the Saturn games I mentioned, at least the games don't have any lighting, that may indicate that they are 16-bt textures. (ie 32 colors by 8 shades, 16 colors by 16 shades, etc)īy "they're" are we talking about the last games I mentioned, Ridge Racer 4 and Gran Turismo, or the first, Virtua Fighter 2, Sega Rally and Daytona USA/CCE? Also, I didn't know that the VDP2 could light VDP1 polygons. You could also use the shading/lighting workaround here too, but even more limited. (with 4 bit being defined by an offset within 256 colors -so any consecutive 15 colors) (the more light levels/shades you dedicate the palette to, the less flexible the color choices can be -you get 2048 CRAM entries, so you could use that as 256 colors of 8 shades, 128 colors of 16 shades, etc)Īs for 8-bit color mode, you can have 4 or 8-bit textures iirc. (since you'd have to manually modify the palette offsets selected for various textures)ĭoing this also limits available color and light levels though.
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(so sprites or polygons that are shaded and/or translucent -relative to other VDP1 pixels- must use direct color)Īs such, you'd need to sacrifice those effects to allow 4 and 8-bit textures to be used (or at least avoid those effects on all surfaces using indexed textures).Īgain, there would be software workarounds for shading indexed color textures (namely organizing VDP2 CRAM to allow banks of colors at different shades/light levels), but that's limited to flat shading and still adds CPU overhead compared to VDP1 RGB shading. RGB textures can only be 16-bits (directly poiting to 15-bit RGB values), and only 15-bit RGB textures/pixels (on the framebuffer AND texture source ends) can be blended or shaded by VDP1. (RGB pixels are limited to fixed priority -common to the entire framebuffer plane- and have no alpha blending support either -either opaque or full-screen translucent) (similar to color options for VDP2 tiles) There's also additional bits available for VDP2 priority and alpha blending. Paletted pixels can be 4, 8, or 16-bits, with 16-bit pixels directly selecting colors from VDP2 CRAM and 4 and 8-bit pixels using an offset to select what segment of CRAM to use. In 16-bit color mode (not 8-bit/256 color framebuffer mode), VDP1 can render both 15-bit RGB and paletted/indexed color pixels (the MSB of each pixel selects which type is used). You are saying that in direct RGB the VDP1 needs to use "large" uncompressed 16-bit textures, but for "indexed," which I understand as 4-16-256 color, VDP1 can lower the resolution of the textures to compensate? Did either the PS1 or Saturn every render direct RGB textures in game? Wait, so maybe I misread this the first time.
You could see why even getting to grips with Saturn seemed a pain in the arse without inventive thinking.Īgain, since you can mix pixel colorspace types freely (in 16-bit framebuffer mode), you could have a game using a mix of untextured smooth-shaded polygons as well as flat shaded (or unshaded) indexed color polygons and sprites (though VDP1 translucency would be impractical -RGB can only blend with RGB), or also very limited use of shaded textures too. Overall its like coding for any other part of the Saturn and requires careful consideration for each part (i.e the dual SH-2's), lack of ADPCM, and limited texture space to use and knowing when and where to use shading tastefully so as not to bog the system down. I think the issue is a trade-off between shading/lighting and or texture resolution, maybe the issue was less down to performance and more vram considerations? A lot of games that do use Gouraud shading suffer trade-offs in texture resolution.
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