GP32 65536 Confusion

[ThomasS]

(I searched the forum but didn't surprisingly find anything about that)
I always thought the GP32 has 65536 colours (it's even written on the gamepark package), but starting coding in 16 Bit mode I discovered that via the macro (from CHN's source code)

#define GP_RGB24(r,g,B) (((((r>>3))&0x1f)<<11)|((((g>>3))&0x1f)<<6)|((((b>>3))&0x1f)<<1))

you only get 5 bit for red, 5 bit for green, 5 bit for blue, the very first bit is unused (5-5-5-0 format).
That are only 2^15 = 32*32*32 = 32768 colours.
So I tried to verify and switched bit 0 on/off in a loop, but I couldn't see any difference in colour shade on my GP32.


Is CHN's macro wrong(actually it works quite good except for that possible 1 bit loss...) or what's the correct colour format?

 

[Charge]

The macro is correct, the last bit doesn't do anything so you only have 2^15 colours. You could use it yourself though, for some form of collision detection or somthing.

 

[ZardozJones]

Hi

no - the bottom bit does affect colour - you can use it to brighten colours - or only on the green channel as usual. so the gp32 really does have 64k colours.

 

[Arda]

Yes gp32 has 64K colours. if you set last bit to 1, colours get brighter.

and I'm happy that ZJ is showing up here lately, I hope he still works on gp32.

 

[Charge]

Fair enough, I'll have to try editing it then.

 

[GiG]

That are only 2^15 = 32*32*32 = 32768 colours.

Well, it is difficult (impossible) to give the same number of bits to each colour if you have 16bit and RGB codes :lol:
It would be possible with CMYK.

Anyway... "only" 32768 colours you say? What are you planning to make that needs more colours? I am curious

 

[synkro]

well.. pr0n needs a lot of flesh tones you knwo... :blink:

 

[ThomasS]

thx for clearing it up, but still 1 question:

so "brighten colours" means actually "brighten only the green channel" or "brighten all channels"? (if only the green channel is affected, r(5):g(5):b(5):g(1) would be a strange format, so I guess it brightens all colours...)

(... and I assume the difference won't be probably visible at all, so it's more or less a theoretical question...)

 

[ZardozJones]

Hi

I think it means brighten all colours, and If I remember it's inverted so 1 = dark 0 = bright. The green thing I was talking about, just ment I only use it on the green channel for some trickery so just ignore that