SGIS_generate_mipmap

OpenGL OpenGL: Advanced Coding
1

I’m just curious about this, but is this extension hardware accelerated ? If yes, which cards ? GF3 only or GF1,2,3

2

Its accelerated on my GF2, so GF1 also must accelerate it. And its really fast - I viewed the NVIDIA demo and it impresses.

-Lev

3

It’s accelerated on Radeon/Radeon 8500 too.

4

Even if it’s not hardware accelerated, the driver vendor may wish to publish the extension. You can easily write an MMX Mip map generator which is substantially faster than the GLU one.

5

You could always simulate the extension by rendering a series of quads to the backbuffer the size of each mipmap level then CopyTexSubImage2D( …, Level, … ).

6

For those new to this extension, we have some sample code available.

-Jason

7

Originally posted by PH:
You could always simulate the extension by rendering a series of quads to the backbuffer the size of each mipmap level then CopyTexSubImage2D( …, Level, … ).

There is a problem with that. I tried to ask about it in this post http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/005233.html , which wasn’t answered so far

8

Moshe Nissim,

I must have missed that post ( I don’t know much about linux, so I wouldn’t be able to answer ).
Anyway, it has to work. It might be a driver problem, maybe this topic can help you ( it appears related ):
http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/005330.html

9

Originally posted by jwatte:
Even if it’s not hardware accelerated, the driver vendor may wish to publish the extension. You can easily write an MMX Mip map generator which is substantially faster than the GLU one.

That would be problematic with rendering to texture, since then the rendered texture have to be downloaded over AGP, mipmapped in software and uploaded again, which would kill performance. I didn’t experience any significant performance difference enabling SGIS_generate_mipmap on a render texture on my old Radeon classic, and it obviously did work.

10

Originally posted by PH:
[b]Moshe Nissim,

I must have missed that post ( I don’t know much about linux, so I wouldn’t be able to answer ).
Anyway, it has to work.
[/b]

PH, saying “it has to work” means you tried it and it did work? (in Windows, or wherever). I suspect it is not an OS problem, but internal conversion between two internal representations – one which is better for SubLoading (linear raster order) and another whith is better for from-drawable Copy (something compatible to drawable representation, tiled or something)