View Full Version : The rummy and abysmal problem ! Great Master give some direct please!

01-27-2001, 01:39 PM
I am do with some game maps,this file has a format of so-called "pixel-16".
I know that our windows has a display mode of 16-bit color.
If the R,G,B all have 3 byte,they are 24-bit.each 1 byte,8-bit.rage from 0 to 255.
but when they are 16-bit,2 byte...well,I am lost..How can they describe the 256 kinds of Rs,Gs,Bs?
I study on the pixel-16 game maps,and get some data, such as:
a pixel R=32,G=56,B=0,it store in hex of E0 10.
a pixel R=16,G=48,B=0,it store in hex of C0 08.
a pixel R=48,G=80,B=0,it store in hex of 40 19.
a pixel R=31,G=48,B=0,it store in hex of C0 0C.

Yeah~,I can not work out the rule of them.
RGB will be Converted to BGR,and the G maybe store in 6-bit,the R in 5-bit,B in 5-bit, am I Right?

But how they store in hex?
How can i read the map in my opengl application? fopen() can not read by bits.
Must i use the << or >> or & or | on a byte?

In the evil DirectX,maybe I can use the creating and get a Surface and lock and copy and ...to use this map DIRECTLY.[The files from Micr$oft are named "Direct",En..maybe it is reasonable.8) ]

What to do in OpenGL?


01-27-2001, 10:11 PM
Depends on the pixel format, since you can have 555, or 565 for example. Those are bits... (that is a 16-bit display). So 5 bits for RGB, or 5 for R&B, and 6 for G.

Does that help?
(I am a little confused what you want, since I don't know anything that reads bits in file I/O except a nibbler drive imager. You just read in the bytes, and then you can do whatever you want with the data) How is the data stored? If it is a .bmp, that check out image readers that handle that, same goes for .tga, .jpg and whatever else.

01-28-2001, 09:33 AM
Ok,thank you for your help.I should describe my matter in detail.

http://www.opengl.org/discussion_boards/ubb/rolleyes.gif Q1: 16-bit pixel as 5-5-5-1,how they store?
following is two bytes in memory( http://www.opengl.org/discussion_boards/ubb/tongue.gif though it looks ugly ):


Is it as 1-5 store the 5-bit R , 678 and ab store the G,cdefg store B,and h for the 1-bit reserved bit?

or get some change in order?As hgfed for R,cba87 for G so-so...

or the [12345678] follow the [abcdefgh]
as: [abcdefgh12345678] and so-so..

any idea?

http://www.opengl.org/discussion_boards/ubb/rolleyes.gif Q2:Can i use OpenGL on this 5-5-5-1-pixel format?What should i setting?

http://www.opengl.org/discussion_boards/ubb/rolleyes.gif Q3:How can this 5-bits describe a 256 color?maybe it never desribe 256 color per R\G\B,but as i know,5-bit only can enum 0-32,ok,there must be some thing like a projecting map...or how can 5-bit get the color with a R-value of 124 ?
so, wanna operate a byte with bit is easy,but after i get a mass of numbers between 0 and 32,they can not use as RGB value,En~~~I have no idea to deal with those bit-rascals. http://www.opengl.org/discussion_boards/ubb/wink.gif

http://www.opengl.org/discussion_boards/ubb/rolleyes.gif Q4:where can i find some doc about the so-called "VBE"?

sorry for my poor english,I try my best to learn it.but it seem like .....Oh~Great Genghis Khan,in my poor english vocabulary I even can not find a exact english word to observe on it. http://www.opengl.org/discussion_boards/ubb/confused.gif

01-29-2001, 09:45 AM
I look up my redbook again and find the GL_RGB5 En.....I think this is only the way to solve this problem,but when i get though more deeply,I find i am wrong.
the GL_RGB5 only define the internal format,it do nothing with the source image.
so if you want load a image,ou must get byte or bytes.

any idea?

is there any func in opengl can copy data from my mainboard memory into my card memory?

01-29-2001, 02:39 PM
If you are using OpenGL1.2, you can set the type(not format) to GL_UNSIGNED_SHORT_5_5_5_1 or GL_UNSIGNED_SHORT_1_5_5_5_REV or sth. like that to read your data. with OpenGL1.1 or earlier, you would have to studied the bit assign of you data and expand it to a RGB or RGBA(24bit or 32 bit), then use OpenGL to read it.

[This message has been edited by Nil_z (edited 01-29-2001).]

01-30-2001, 02:12 PM
Yeah~~thank you for your help.

Just think about that many users don't have the opengl 1.2,my application may can not work.

as i know, opengl 1.2 is not shipped with win98/winMe.

since matter like this,I have to use the Dx and draw it and copy screen and save as bmp and... http://www.opengl.org/discussion_boards/ubb/wink.gif