Mysterious Black Pixels

[Ghost_Fang]

I'm not sure if this belongs here in Engine Programming or not. I think it does because the issue seems to be only apparent in my DQuake PSP engine. Other tools such as Crafty BSP viewer has no such anomalies. It appears to me that those might be "fullbright" colors not rendering right (to which i have no use for). This is a HLBSP map made in Hammer 3.5.3 and i don't use wadinclude. Has anyone ever experienced this and have fixed/remedied this?

In Game:


Source Texture:

[Spike]

HLBSP has per-texture palettes (meaning the last 32 indexes could be any colour). it also has no fullbrights.
it also has toolchain licensing issues.

[Ghost_Fang]

I figured as much, it was just a speculation i had because I first noticed it on a light texture that I have. I scrubbed through the engine to try to find ANYTHING about pixel manipulation i cannot find any.

[Ghost_Fang]

(cannot find the edit button if there is one anymore)
So what would be my issue then? Have you seen anything like this?

[Spike]

if its nulling out the last 32 palette indexes to black because they're within the last vid.fullbright pixels, and then not generating a fullbright image because its an hlbsp, then that might explain it quite well. its certainly possible.
engines are vastly different nowadays so I can't give you many more hints other than vid.fullbright or the number 32 if its hardcoded, or possibly 224. also check to see if it has some cvar to disable fullbrights (not to be confused with the fully-lit lightmaps, of course). good luck...

[frag.machine]

You can open the texture in any image editor and check the pixel colors to confirm (or discard) the palette theory. But if the dot patterns are constant in all places where the texture is used I can't think of any other suspect.

[ceriux]

perhaps it has to do with the texture compression used on psp engines?

[drm_wayne]

[frag.machine]

Actually index 255 in Quake palette was always meant to be a transparent, null color (all 2D graphics such fonts, menu elements and even sprites use it this way). Kurok only extended the concept to alias models. The problem Ghost_Fang reported seems related to fullbrights, as Spike observed.

[Spike]

conchars(read: quake's font) uses 0 for transparent. because special cases are fun.
and 255 is pink, not black.
255 is only 'black' if you consider it transparent, in which case you should be using premultiplied alpha which results in pink*0=0=black. obviously this doesn't apply if its an 8-to-24 lookup table as that has no alpha channel and thus cannot be transparent and thus must be pink, not black.
not supporting premultiplied alpha will result in halos. yes, black halos are generally better than pink halos, but any kind of halo is still a bug - even the filling described below would be preferable to black halos.

For bsp textures, palette index 255 is transparent ONLY if the texture's name has a leading {. Due to depth issues with alpha blending, premultiplied alpha is no longer reliable, and thus engines will probably switch to alpha testing, and in order to avoid obvious halos, these transparent pixels should be filled in with the average of their neighbouring (valid) pixels (but with alpha 0).

Note that halflife has PER-TEXTURE palettes, thus some bug inside your 'VID_SetPalette' function won't affect your halflife textures. Because of the filling described above, it shouldn't affect your q1 textures with { in them either, but it WILL affect valid q1bsp textures/skins that happen to use index 255.

Obviously, because halflife textures have their own per-texture palette, and halflife never supported fullbrights, any attempt to utilise fullbrights in said halflife textures is a bug.

Obviously there could be all sorts of bugs in random projects, but these are the most likely ones that I can think of.

[drm_wayne]

[Ghost_Fang]

[drm_wayne]

glad i could help

you can also try to upload all 8bpp paltextures to the PSPGU with the built-in DXT compressor,
this will save alot of ram.

[Ghost_Fang]

[jitspoe]

#BlackPixelsMatter

Sorry. Couldn't resist.