plib-devel

[Plib-devel] texture compression

[<tia...@sa...>]

Hello

I was wondering if i or someone else can add texture compression support 
to plib, which i believe can be done without disrupting the current plib 
behaviour and with few files being affected.

Below is my original post to the FlightGear devel list, with a quick 
hack patch.

Currently we're still discussing this, so no further details, but if we 
go ahead with it, is it alright regarding plib?


Thanks

Cheers,
Tiago


***********************************************************************
***********************************************************************
Hello

I'm having a HW problem and i can't enable AGP in linux, which makes the
hunter, b1900d and the Nimitz lower FPSs dramatically, which i believe
is caused by the NVRAM filling up with textures thus forcing texture
transfers to the card (GF4 MX 440 64MB)

so after Surge mentioned texture compression, i added it in plib, with
amazing performance improvements in those situations, It also appears to
be improving FPS in general in other situations.

it doesn't check for the extension, **before trying**, check glxinfo for
the presence of "EXT_texture_compression_s3tc"
it's just an ugly hack, works for me and likely everyone else with s3tc, 
but it's bad code, i know,

a brief explanation: http://www.digit-life.com/articles/reviews3tcfxt1/
spec:
http://oss.sgi.com/projects/ogl-sample/registry/EXT/texture_compression_s3tc.txt


i have no experience with patches, but here it is, against plib
1.8.4,for those interested.
added one line, made one token change:

diff -cr plib-1.8.4/src/ssg/ssgLoadTexture.cxx
plib-1.8.4ext/src/ssg/ssgLoadTexture.cxx
*** plib-1.8.4/src/ssg/ssgLoadTexture.cxx    2003-06-27 08:15:15.000000000
+0000
--- plib-1.8.4ext/src/ssg/ssgLoadTexture.cxx    2006-01-07
16:44:17.000000000 +0000
***************
*** 24,29 ****
--- 24,30 ----

   #include "ssgLocal.h"

+ #define PROXY_TEXTURES_ARE_BROKEN

   struct _ssgTextureFormat
   {
***************
*** 161,167 ****
       total_texels_loaded += w * h ;

       glTexImage2D  ( GL_TEXTURE_2D,
!                      map_level, zsize, w, h, FALSE /* Border */,
                               (zsize==1)?GL_LUMINANCE:
                               (zsize==2)?GL_LUMINANCE_ALPHA:
                               (zsize==3)?GL_RGB:
--- 162,168 ----
       total_texels_loaded += w * h ;

       glTexImage2D  ( GL_TEXTURE_2D,
!                      map_level, /*zsize*/ 0x83F3, w, h, FALSE /*
Border */,
                               (zsize==1)?GL_LUMINANCE:
                               (zsize==2)?GL_LUMINANCE_ALPHA:
                               (zsize==3)?GL_RGB:

R: [Plib-devel] texture compression

[Paolo L. <p.l...@ci...>]

Sorry, just a question: what about actually loading the DDS texture =
image
data?

I.e. putting a new zsize mode parameter in the glTexImage2D call suppose =
we
are supplying proper pixed data, and, beside the large pixel data block, =
we
should also read w, h, and the GL_COMPRESSED_RGBx_S3TC_DXTx_EXT mode off =
the
file. Is there code for this too?

Greetings -

Paolo Leoncini


> -----Messaggio originale-----
> Da: pli...@li...=20
> [mailto:pli...@li...] Per conto di=20
> Tiago Gusm=E3o
> Inviato: marted=EC 10 gennaio 2006 17.51
> A: pli...@li...
> Oggetto: [Plib-devel] texture compression
>=20
>=20
> Hello
>=20
> I was wondering if i or someone else can add texture=20
> compression support=20
> to plib, which i believe can be done without disrupting the=20
> current plib=20
> behaviour and with few files being affected.
>=20
> Below is my original post to the FlightGear devel list, with a quick=20
> hack patch.
>=20
> Currently we're still discussing this, so no further details,=20
> but if we=20
> go ahead with it, is it alright regarding plib?
>=20
>=20
> Thanks
>=20
> Cheers,
> Tiago
>=20
>=20
> **************************************************************
> *********
> **************************************************************
> *********
> Hello
>=20
> I'm having a HW problem and i can't enable AGP in linux,=20
> which makes the hunter, b1900d and the Nimitz lower FPSs=20
> dramatically, which i believe is caused by the NVRAM filling=20
> up with textures thus forcing texture transfers to the card=20
> (GF4 MX 440 64MB)
>=20
> so after Surge mentioned texture compression, i added it in=20
> plib, with amazing performance improvements in those=20
> situations, It also appears to be improving FPS in general in=20
> other situations.
>=20
> it doesn't check for the extension, **before trying**, check=20
> glxinfo for the presence of "EXT_texture_compression_s3tc"=20
> it's just an ugly hack, works for me and likely everyone else=20
> with s3tc,=20
> but it's bad code, i know,
>=20
> a brief explanation:=20
> http://www.digit-life.com/articles/reviews3tcfxt1/
> spec:=20
> http://oss.sgi.com/projects/ogl-sample/registry/EXT/texture_co
> mpression_s3tc.txt
>=20
>=20
> i have no experience with patches, but here it is, against=20
> plib 1.8.4,for those interested. added one line, made one=20
> token change:
>=20
> diff -cr plib-1.8.4/src/ssg/ssgLoadTexture.cxx
> plib-1.8.4ext/src/ssg/ssgLoadTexture.cxx
> *** plib-1.8.4/src/ssg/ssgLoadTexture.cxx    2003-06-27=20
> 08:15:15.000000000
> +0000
> --- plib-1.8.4ext/src/ssg/ssgLoadTexture.cxx    2006-01-07
> 16:44:17.000000000 +0000
> ***************
> *** 24,29 ****
> --- 24,30 ----
>=20
>    #include "ssgLocal.h"
>=20
> + #define PROXY_TEXTURES_ARE_BROKEN
>=20
>    struct _ssgTextureFormat
>    {
> ***************
> *** 161,167 ****
>        total_texels_loaded +=3D w * h ;
>=20
>        glTexImage2D  ( GL_TEXTURE_2D,
> !                      map_level, zsize, w, h, FALSE /* Border */,
>                                (zsize=3D=3D1)?GL_LUMINANCE:
>                                (zsize=3D=3D2)?GL_LUMINANCE_ALPHA:
>                                (zsize=3D=3D3)?GL_RGB:
> --- 162,168 ----
>        total_texels_loaded +=3D w * h ;
>=20
>        glTexImage2D  ( GL_TEXTURE_2D,
> !                      map_level, /*zsize*/ 0x83F3, w, h, FALSE /*
> Border */,
>                                (zsize=3D=3D1)?GL_LUMINANCE:
>                                (zsize=3D=3D2)?GL_LUMINANCE_ALPHA:
>                                (zsize=3D=3D3)?GL_RGB:
>=20
>=20
> -------------------------------------------------------
> This SF.net email is sponsored by: Splunk Inc. Do you grep=20
> through log files for problems?  Stop!  Download the new AJAX=20
> search engine that makes searching your log files as easy as=20
> surfing the  web.  DOWNLOAD SPLUNK!=20
> http://ads.osdn.com/?ad_id=3D7637&alloc_id=3D16865&op=3Dclick
> _______________________________________________
> plib-devel mailing list
> pli...@li...=20
> https://lists.sourceforge.net/lists/listinfo/plib-devel
>=20

Re: R: [Plib-devel] texture compression

[<tia...@sa...>]

Hello

If i understand correctly, .DDS are pre-compressed image files. I think 
coding what you are suggesting would be easy, but it would require that 
we decompress the textures ourselves in case the user doesn't have the 
extension (and the final result would have the same compression artifacts).

In FG's case, i think the best option is make it so we can override the 
default Z from FG/SimGear, thus making extension checking our problem 
and allowing the user to choose if he prefers no compression (and so no 
compression artifacts).


Cheers




Paolo Leoncini wrote:
> Sorry, just a question: what about actually loading the DDS texture image
> data?
> 
> I.e. putting a new zsize mode parameter in the glTexImage2D call suppose we
> are supplying proper pixed data, and, beside the large pixel data block, we
> should also read w, h, and the GL_COMPRESSED_RGBx_S3TC_DXTx_EXT mode off the
> file. Is there code for this too?
> 
> Greetings -
> 
> Paolo Leoncini