Need some help with GL_EXTENSIONS

[ElDonAntonio]

Hi guys,

I'd like to use a few gl extensions in a small piece of C++ software I'm starting, but I can't seem to find any documentation anywhere on the web. Can anyone direct me to some useful docs?
I'm in particular interested in GL_EXT_TEXTURE3D, but reading up on other extensions could be interesting :)

Thanks!

[mrbill]

I'm in particular interested in GL_EXT_TEXTURE3D, but reading up on other extensions could be interesting :)

Thanks!

www.opengl.org Take a look at the Documentation link on the left side of the page under Developers. There's general OpenGL Extensions information, as well as the actual specifications found at the OpenGL Extension Registry.

But, 3D Textures was promoted to core with OpenGL 1.2 (28 March 1998), so you will find the documentation for that in the core specifications. (OpenGL 1.4 is the current released specification, 1.5 is coming soon.)

-mr. bill

[ElDonAntonio]

thanks for the tip! I found some good stuff, but I still have a few questions, maybe the gurus on this forum can help me:

-is there a limit in size for a 3D texture? I guess it's stored in the video card's memory, so would that be the ultimate limit?
-what kind of formats are accepted for each voxel? can I use more precise values for each color component than the standard 8 bit?
-Is it possible to access the texture from within a shader?

[Humus]

-is there a limit in size for a 3D texture? I guess it's stored in the video card's memory, so would that be the ultimate limit?

Call glGetIntegerv() with GL_MAX_3D_TEXTURE_SIZE_EXT.

-what kind of formats are accepted for each voxel? can I use more precise values for each color component than the standard 8 bit?

You can use all formats available for 2D textures. So 16bit / channel is available. With extensions you can get float formats too.

-Is it possible to access the texture from within a shader?

Yup.

[ElDonAntonio]

Hi Humus, thanks for the reply, I guess I couldn't ask for a better guru :)

can you just give me some details about the floating point precision? what extensions would I need to use?

[ehart]

The only extension that supports floating point 3D textures at the moment is ATI_Texture_Format_Float. It allows you to specify either 32-bit or 16-bit float sizes.

-Evan