GL_KTX_buffer_region what is it?

OpenGL OpenGL: Advanced Coding
1

not sure if this post should go in the beginners forum…

but my graphics card (ATI Radeon) supports this opengl extension, but I can’t find any information about it…

what is it?

what does it do???

thanks

2

Pseudo specs are here:

http://www.west.net/~brittain/3dsmax2.htm#OpenGL Buffer Region Extension

http://www.eur.autodesk.com/develop/devres/heidi/oglspecs.htm

Use a better search engine

[This message has been edited by Relic (edited 03-02-2001).]

3

You should read WGL_ARB_buffer_region at the extension registry. This extension has a real spec and is ARB approved. It is intended to legitimize the old KTX extension.

Essentially, it allows the application to do a “save this region” and “restore this region” of a depth or color buffer (stencil, too, I think) in a very optimized way. You could do the same thing with readpixels/drawpixels, but that’s pretty much the worst case for performance.

4

I think the Radeon only supports the Kinetix extension not the ARB one.

WGL_ARB_buffer_region as well as GL_KTX_buffer_region can save stencil regions.

I’ve got a question for you Cass (or Matt). Will the GF3 support the WGL_ARB_pbuffer extension, and can’t a pbuffer be used roughly for the same purpose as an auxiliary buffer (the question could be what’s the purpose of pbuffers)?

5

Our next driver release will support pbuffers on all chip architectures – TNT, GeForce, and GF3.

We have a lot of interesting plans for things we can do with pbuffers.

Pbuffers and aux buffers each have their own advantages and disadvantages. Most notably:

  • your aux buffers are always the same size as your window (convenient if you want that; a problem if you want a temp buffer larger or smaller than your window)
  • aux buffers also are always the same color depth, and if you are using multisample, are bound to the same multisample buffer as your window
  • aux buffers share your window’s depth buffer, while pbuffers can have their own
  • a pbuffer doesn’t have to have a color buffer; you can have a depth-buffer-only pbuffer

They’re different mechanisms and are used for different things.

[Hmm, maybe I should go ahead and implement those aux buffers…]

  • Matt