5551 format problems.

[HexDump]

Hi,

I´m trying to use the 5551 format to draw sprites with alpha test. The PSPSDK doc states that n this format pixels come in a RGBA format, but I have noticed that order must be swaped in order to have correct colors, I mean ABGR, is doc wrong?.

Using this format, I achieved to have correct colors but A channels seemed not work. Any Idea?.


Thanks in advance,

HexDump.

[Shito]

From what I've tried, yeah, 5551 RGBA is indeed 1555 ABGR, but I had no problem getting the alpha channel to work, though.

[chp]

It all depends on how you look at it. I've used the order of bits that Sony has used in public, and I think they think of it as going from bit 0 to bit 31 in their naming.

Using this format, I achieved to have correct colors but A channels seemed not work. Any Idea?.

Make sure you pass GU_TCC_RGBA to the 2nd parameter of sceGuTexMode(), otherwise it won't read the alpha-component.

[Shito]

Kinda makes sense, but why is it reversing again in 32 bits then ??
From what I've seen, 32 bits is 8888 ARGB.

[HexDump]

Thanks for the answerings. A little more question to chp, is it really needed to put this format when no using 3D at all?, I´m only writing short ints to VRAM, it sounds odd to me having to set this flag to only do this and get the alpha chan working.

Thanks in advance,
HexDump.

[chp]

Yes it's required if you want to use anything that uses the alpha-channel of the texture. Without it, texture alpha will not affect the fragment color, and you'll have a hard time using it for alpha-blending or testing.