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MagicCarpet

do exist some better than DXT ?

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Quote:
Original post by bubu LV
JPG and PNG.


If i know.., JPG and PNG dont save RAM space.

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As far as I know, there's only DXT. PNG and JPEG still need to be decompressed in RAM because the video card can't deal with them natively - that's the whole point in DXT - they're compressed in video memory (Or wherever the texture is), and the video card can deal with them in that state.

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There are of course other compression formats for textures, but they mostly lack support by graphics APIs and/or video cards. And whether they are "better" depends on the use case: Saving more RAM means in general to drop another piece of quality, and some kinds of textures are less sensitive to this than others.

ATI's 3Dc is e.g. mentioned herein:
http://www.gamasutra.com/features/20051228/sherrod_01.shtml
Maybe there is hardware support in newer ATI cards.

Another thing is the vector quantization as is described e.g. here:
http://www.gamasutra.com/features/20010416/ivanov_01.htm
This format can compress very well, but definitely lacks support. It is also not suited for compression on-the-fly, since the effort of compression is very high while the effort of decompression is very low.

Unfortunately I don't remember the name of the format 3dfx has developed and that was overtaken by NVidia.

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Quote:
Original post by haegarr
There are of course other compression formats for textures, but they mostly lack support by graphics APIs and/or video cards.
If they do exist then it'll be via custom 4CC's passed in-place of regular D3DFMT values. There are quite a few of these kicking around - but they're often highly dependent on the underlying hardware (which is unsurprising given that they're not defined as part of the D3D standard) and not usually that well documented. Digging around the Nvidia and ATI developer sites (and SDK's) sometimes reveals the necessary details.

Quote:
Original post by haegarr
Unfortunately I don't remember the name of the format 3dfx has developed and that was overtaken by NVidia.
You mean S3TC? If so, I'm pretty sure that maps to one of the DXTn formats - just can't remember which [smile]


For future reference, D3D10 renames DXT formats to be BC - Block Compressed - and adds a couple of extra ones. From what I can gather the BC5_UNORM/BC5_SNORM formats are analagous to ATI's custom 3Dc stuff...

hth
Jack

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Quote:
Original post by jollyjeffers
Quote:
Original post by haegarr
Unfortunately I don't remember the name of the format 3dfx has developed and that was overtaken by NVidia.
You mean S3TC? If so, I'm pretty sure that maps to one of the DXTn formats - just can't remember which [smile]

S3TC is the abbreviation for "S3 texture compression" and was invented by Savage S3 and AFAIK introduced with their "Savage 3" gfx card. And yes, you are right in that the DXTn's are in fact the S3TC formats, or at least derived from it.

But what I meant was FXT1 as is a texture compression format invented by 3dfx (I've remembered it just-in-time for this reply :)

If interested in, a comparison can be found e.g. here:
http://www.digit-life.com/articles/reviews3tcfxt1/


EDIT:
Quote:
Original post by jollyjeffers
For future reference, D3D10 renames DXT formats to be BC - Block Compressed - and adds a couple of extra ones. From what I can gather the BC5_UNORM/BC5_SNORM formats are analagous to ATI's custom 3Dc stuff...

Oh, that is of interest, at least for me. Thanks for the info.


EDIT2: Some naming corrections due to ET3D's hint below.

[Edited by - haegarr on November 6, 2006 8:30:13 AM]

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Quote:
Original post by haegarr
S3TC is the abbreviation for "Savage 3 texture compression" and was invented by Savage and AFAIK introduced with their "Savage 3" gfx card.
Yup, I know - my first half-way decent 3D card was a Savage 4 (I think - whatever came before the mistake that was the Savage 2000 [wink]).

Given that Savage changed names several times, got bought out a few more times I had a vague memory that they had been rolled into 3DFX prior to Nvidia grabbing them...

Quote:
Original post by haegarr
But what I meant was FXT1 as is a texture compression format invented by 3dfx (I've remembered it just-in-time for this reply :)

If interested in, a comparison can be found e.g. here:
http://www.digit-life.com/articles/reviews3tcfxt1/
Will go have a read of that [smile]


Quote:
Original post by haegarr
Quote:
Original post by jollyjeffers
For future reference, D3D10 renames DXT formats to be BC - Block Compressed - and adds a couple of extra ones. From what I can gather the BC5_UNORM/BC5_SNORM formats are analagous to ATI's custom 3Dc stuff...

Oh, that is of interest, at least for me. Thanks for the info.
Yeah, I thought it was pretty interesting given that it's a required feature for all IHV's. I haven't quite finished it yet, but I've got an example of using BC5 formats in the 'Techniques for Per-Pixel Lighting' chapter of my book [smile]

Cheers,
Jack

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Quote:
Original post by haegarr
S3TC is the abbreviation for "Savage 3 texture compression" and was invented by Savage

The company was called S3, which is why the compression is called S3TC. The name of the chip was Savage3D. See http://en.wikipedia.org/wiki/S3_Graphics for more about S3.

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