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lekana123
12-20-2001, 10:13 AM
Im new in opengl, so can anyone tell me what opengl extensions are? What do they do?

Thanks

Bob
12-20-2001, 11:02 AM
They extend the functionality of the core. The OpenGL core is just a basic set of functions, and if some vendor want more functions, they are added as extensions.

Jambolo
12-20-2001, 12:21 PM
Ok, I know what extensions are, but figuring out how to use them is another story. Here are some questions and issues. I am using a Savage 4 and Win98.

1. My version of OpenGL is 1.1. Can I get a later version (1.3)?

2. My Savage4 supports the extension GL_ARB_multitexture. I looked in the extension registry and the entry for this was removed since it is now standard. Lot of good that does me since I am still on 1.1!!!

3. Ok, I found the GL_ARB_multitexture extension in the 1.2.1 document. I wrote the function prototypes. Now the problem is that the enumeration values are not listed. Where do I find these values?

4. The GL_S3_s3tc extension is also supported, but it is not even in the extension registry. Where do I find the docs for this extension?

This all seems too convoluted. I must be missing something. It seems to me that if my video card and drivers support an extension, there would be a header file somewhere with function prototypes and enumeration values already defined.

nemesis
12-20-2001, 11:43 PM
> Where do I find these values?

Yes, Jambolo, you are missing something. You need the glext.h header file. You can find it somewhere in the net.

-nemesis-

Bob
12-21-2001, 02:22 AM
1: Depends on whether there are newer drivers for your card or not. If the newest driver are version 1.1, then you're out of luck.

2: The document at the registry is removed cause it's no longer an extension in the latest version of OpenGL (1.3 that is). But this doesn't mean that the extension itself is gone. The documentation for multitexturing can be found in the OpenGL specification now. So don't worry about that.

3: The constants should be mentioned in the specification if I remember correctly. But as nemesis says, you can download glext.h (http://oss.sgi.com/projects/ogl-sample/ABI/glext.h) , which defines constants and function prototypes for most extensions.

4: Then I don't know what you can do. Try contact S3 and ask them if they have the spec., or where to find it.