Results 1 to 10 of 10

Thread: Compressing 3D Textures for S3TC

  1. #1
    Guest

    Compressing 3D Textures for S3TC

    Hi,

    I'm trying to figure out how OpenGL compresses and mipmaps 3D textures. From the spec, I gather that mipmaps are just 2x2x2 down-sampled (cube filtered) versions of the original. But how might one compress 3D images for S3TC, by compressing each slice independently, or by taking slices together somehow? I have a working version of the 2D version, but I'm not sure how to proceed with 3D. I'm thinking slices but not sure.

    I know that OpenGL can do this for me, but I want this addition to my library.

    Any insight would be appreciated.

    Thanks

  2. #2
    Guest

    Re: Compressing 3D Textures for S3TC

    The more I think about it the more I think it has to be independent slices, since I see nothing in the s3tc spec about volumes. Probably just the way it is for 2D, only repeat for each slice. That's got to be it!

    Sorry guys. If anyone disagrees, please chime in!

    Thanks

  3. #3
    Senior Member OpenGL Pro sqrt[-1]'s Avatar
    Join Date
    Jun 2002
    Location
    Australia
    Posts
    1,000

    Re: Compressing 3D Textures for S3TC


  4. #4
    Guest

    Re: Compressing 3D Textures for S3TC

    Thank you very much for pointing that out. That's exactly what I was looking for (right under my nose).

    This spec seems to confirm my original suspicion, that each slice (layer) is calculated independently of the others. DXT1 size is 8 bytes in 2D 4x4, but 16 bytes in 3D 4x4x2 and so on. I initially feared I'd need a new algorithm to convert the blocks, but apparently that's not the case. What a relief!

    Thanks!

  5. #5
    Member Newbie
    Join Date
    Nov 2005
    Location
    Australia
    Posts
    33

    Re: Compressing 3D Textures for S3TC

    This is something I am very interested in.
    But it is unbelievably difficult finding the information out on the web.

    Do all cards now, pretty much, support hardware compression of 3D textures ?

    Jon
    "Can we all please just accept the proven fact that proprietary formats DIE, and stop arguing?" -APB

  6. #6
    Super Moderator OpenGL Lord
    Join Date
    Dec 2003
    Location
    Grenoble - France
    Posts
    5,574

    Re: Compressing 3D Textures for S3TC

    unbelievably ...
    http://delphi3d.net/hardware/index.php

    For 3D textures, this extension is nvidia-only apparently :
    http://delphi3d.net/hardware/extsupp...ompression_vtc

  7. #7
    Member Newbie
    Join Date
    Nov 2005
    Location
    Australia
    Posts
    33

    Re: Compressing 3D Textures for S3TC

    Quote Originally Posted by ZbuffeR
    unbelievably ...
    http://delphi3d.net/hardware/index.php

    For 3D textures, this extension is nvidia-only apparently :
    http://delphi3d.net/hardware/extsupp...ompression_vtc
    Hi ZBuffer - quick tip - it really pays to read the thread thoroughly before trying to attempt patronizing comments. Good luck in future.
    "Can we all please just accept the proven fact that proprietary formats DIE, and stop arguing?" -APB

  8. #8
    Senior Member OpenGL Pro Zengar's Avatar
    Join Date
    Sep 2001
    Location
    Germany
    Posts
    1,931

    Re: Compressing 3D Textures for S3TC

    I fail to see your problem, John. As ZbuffeR correctly pointed out, only Nvidia provides this extension. The comment was neither patronizing nor inappropriate.

  9. #9
    Super Moderator OpenGL Lord
    Join Date
    Dec 2003
    Location
    Grenoble - France
    Posts
    5,574

    Re: Compressing 3D Textures for S3TC

    Yeah, jon is complaining one an a half year after I gave an useful answer ... I guess he was very upset

  10. #10
    Senior Member OpenGL Pro Zengar's Avatar
    Join Date
    Sep 2001
    Location
    Germany
    Posts
    1,931

    Re: Compressing 3D Textures for S3TC

    Wow, I haven't looked at the date Oo

    Funny

Similar Threads

  1. Compressing a texture that's already in VRAM
    By VelociChicken in forum OpenGL: Advanced Coding
    Replies: 1
    Last Post: 12-07-2012, 10:03 AM
  2. EXT_texture_compression_latc - Compressing
    By Bruce Wheaton in forum OpenGL: Basic Coding
    Replies: 3
    Last Post: 07-06-2009, 11:19 AM
  3. compressing normals/tangents vector
    By remdul in forum OpenGL: Advanced Coding
    Replies: 1
    Last Post: 08-20-2008, 10:06 AM
  4. compressing normalmaps
    By zed in forum OpenGL: Advanced Coding
    Replies: 17
    Last Post: 10-30-2005, 12:23 PM
  5. compressing the light vector?
    By SirKnight in forum OpenGL: Advanced Coding
    Replies: 3
    Last Post: 07-25-2002, 06:14 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Proudly hosted by Digital Ocean