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16-bit

Started by theonlymcc Sep 26, 2000 at 6:35 AM 4 replies 450+ views

Original Post

Sep 26, 2000 at 6:35 AM

I have tried all this stuff about 16-bit and can''t get it to work. If I use this macro out of WGPFD #define _RGB16BIT(r,g,b) ((b%32) + ((g%32) << 5) + ((r%32) << 10)) and just use 255 for r and 0 for g & b. then the screen is gold. if I use 31 it is still gold. I am using LPDIRECTDRAW7 and LPDIRECTDRAWSURFACE7. I am sure that it compiles right and that it is in 16-bit. Somebody please give me something that works. Say its a function, what variable type do I declare my color? Like in the macro above. Do I declare it a WORD or USHORT or what? I am so confused.

NuffSaid

Sep 26, 2000 at 6:51 AM

You must shift the r value by 11 bits, not 10. That''s where your problem is.

theonlymcc

Sep 26, 2000 at 6:56 AM

Cool. That worked. Just shifted it to 11. Why does that work? And..what type of variable should my color be? Should I make it a USHORT? ULONG? Since it is 16-bit, does that mean when I want to make a color that each rgb value''s max is 31? or is it still 255?
Thanks.

Quantum

Sep 26, 2000 at 7:01 AM

most video cards use 5 bits for red, 6 for green, and 5 for blue

giving you a colour range of 31, 63, and 31 respectively

but some cards still use 555 mode..
you should detect the pixel format and then have a function pointer or something like that...

use lpddsprimary->GetPixelFormat() and then get the dwGBitMask to get which pixel format it is
i cant remember the exact values for the green bit mask atm..

theonlymcc

Sep 26, 2000 at 7:08 AM

I tried using 31,63,31 to see if I could make white. I Blt it to the surface and I get purple but I can get red, blue or green alone. So I tried 31,31,31 and I still got purple. But I just figured it out. I switched the macro from this:
RGB16BIT(r,g,b) ((b%32) + ((g%32) << 5) + ((r%32) << 11))
to this:
RGB16BIT(r,g,b) ((b%32) + ((g%32) << 6) + ((r%32) << 11))

so it works officially. So does that mean My card uses 565? Thanks to all for your help. I am sorry for not catching on as quick as the like here on the board. I apologize for being so cumbersome.

Edited by - theonlymcc on September 26, 2000 8:13:51 AM

furby100

Sep 26, 2000 at 7:36 AM

Your card is 565, yes. The reason it is purple, is that the macro for 565 is in fact:


#define RGB16BIT(r, g, b) ((b%32)+((g%64)<<5)+((r%32)<<11))

or in the faster form:


#define RGB16BIT(r, g, b) ((b&31)|((g&63)<<5)|((r&31)<<11))

However, if you want a to use the macros identically, you should use your macro.

------------------------------
#pragma twice

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