[Nuke]

i just learned about yet another texture format, 3dc/bc5:

http://en.wikipedia.org/wiki/3Dc
http://code.google.com/p/nvidia-texture-tools/wiki/NormalMapCompression

essentially a 2 channel normal map format that encodes both channels in the same way dxt5 alpha works. increasing precision on the u (v?) channel and generally improving normal map quality.

supposedly its supported by both nvidia, and ati, and is compatible with opengl. basicly normal maps are implemented using the hackish (yet industry accepted) dxt5_nm format, which as i understand it has caused some trouble with artifacts on some lower res normal maps, forcing modders to either up the texture resolution or use an 8888 format. compressed or not 2 channels get wasted.

if the shaders are reworked to accept a 2 channel format. modders could choose between 3dc/bc5 and 88AL formats, 4 and 16bpp respectively.

good idea? bad idea?
discuss

[taylor]

3Dc was only available on ATI hardware at the time that the shader code was being developed, which is why I didn't add support for it as a usable format.  Since we didn't (and still don't) have a material system we can't pick and choose maps which means that whatever was going to be supported had to work for everyone.  My card still doesn't support 3Dc as far as I know (NVIDIA 6800GT).

Support for 88AL was added at one point, but since it requires different shaders to work and uses 2x the memory as DXT5_nm, the code for that never made it out of the Xt tree.  It was simply decided to use DXT5_nm and that was it, at least until a material system could be added.  Without a material system we don't really have any choice but to standardize on a single format.

[Nuke]

ah i see.

and what exactly would a materials system require, programming wise. if its just a matter of loading another table into another struct and some bitmap management then it might be something i can do. of course the second i touch actual rendering code id probably get pretty lost.

[Dark RevenantX]

It's generally accepted as something that would require a near-complete graphics code re-write.  Good luck!

[Bobboau]

actually I think what Nuke is asking for would just require a shader rewrite, and everyone who is using the current shaders to convert all of there media (or for projects that want it like this to make there media in this format in the first place).

[DaBrain]

All we need is the ability to use more shaders and switch them per material(texture) in a POF.

Doesn't have to be pretty. Usually, the standard shaders are fine. It's about some special cases where different shaders are required.


@Dark RevenantX
Are you sure about that?
I know it would be quite a bit of work, but never heared it would require re-writing the entire graphics code.