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Ehsan Kamrani
05-28-2005, 01:38 PM
Hi there
Which software is better to make the textures? I use from the photoshop to create the BMP files. But i cannot use from them in my programs. instead, i should open these BMPs with the Paint program and save them again to be able to use them. I need to load the following bitmas:
-RGB( 24 bits )
-RGBA( 32 bits )
-Grayscale( 24 bits )
Which software do you suggest me to make or edit them? Can the Paint program saves the alpha channel?

-Ehsan-

ZbuffeR
05-28-2005, 11:18 PM
I think if you just save as Uncompressed BMP in Photoshop, it will work directly in your program.

For rgba, add an extra channel and edit it. When saving do include it in file.

BTW grayscale can just be 8 bit.

But BMP is a very limited format, and may not be able to handle alpha...

I find TGA to be the easiest format for all these rgb/rgba textures.

Ehsan Kamrani
05-28-2005, 11:55 PM
OK.
Another subject...When i use from the RGB bitmap files and use from the following function:
glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_BLEND );
It does work correctly.But i believe that blending the texture with the surface is depend on the alpha channel--And i haven't used from the alpha channel in my picture.Does the OpenGL add an alpha channel in this case?
Thanks,
-Ehsan-

jide
05-29-2005, 05:14 AM
No, if you specified an RGB image, Opengl doesn't transform it into an RGBA. It simply blends them with the paramters you give to your texture threw glTexEnvi essentially.

I can advise you the red book (OpenGL reference manual), translated into several languages (including french). It explains all about that libraries, and will help you a lot on understanding all major behaviors of opengl.

Hope that can help you.

Ehsan Kamrani
05-29-2005, 06:58 AM
Aww.Thank you. But i had translated this book as well as some other books to my language. I'm completing my knowledge about the OpenGL API and i had forgotten some subjects, since i was learning the OpenML API. I am *reviewing* some subjects.I have studied many books and taught them in my university.
-Ehsan-

jide
05-29-2005, 07:24 AM
I know how hard it is to translate texts into your own language. I've also read many books, but can't teach them since I'm a 'student' :) I also need to be best in gl, this is why I'm here !

You can blend things even if they do not have any alpha values at all. I remember some quiete recent posts (about few months) talking about that, but I cannot remember how the techniques are called.

Unfortunately I cannot say more about that since I'm not an expert with blending (I use it so few). Anyway, targa (tga) seems one of the best choices for managing images with an alpha channel. There's also the png format if I'm not wrong.

regards.

Ehsan Kamrani
05-29-2005, 08:20 AM
Hi Jide
Many special thanks for your reply.Yes we are human. and none of us know anything :rolleyes:
Nice to meet you. :)
-Ehsan-

jide
05-29-2005, 11:24 PM
nice to meet you too.