Texturing DXT3? not clear? --UT2004--

Starstreams · Sep 25, 2005

I’m reading this page
http://udn.epicgames.com/Two/UnrealTexturing#Texture_Formats

I don’t get DXT 3

Is says, "DXT 3 is good for textures with sharply contrasting translucent/opaque areas”
What doses that mean exactly?

DXT 5 seems like it’s the best one for photographic kinds of images like an outside picture taking with your camera.

But what kind of image would DXT 3 be good for? Can anyone go into a little more depth on the kind of image it should be used with?

Advanced Thanks.

Starstreams · Sep 25, 2005

I think I understand better now,
This article doses a better job at comparing the differences and makes sense now.

http://wiki.beyondunreal.com/wiki/Texture_Format

Hourences · Sep 26, 2005

5 is the same as 3 but supports better alpha, thats it
1 is low quality

use 1 whenever possible, darker textures without a lot of different colors (certainly no gradients) will work just fine with 1
All others 3 (like ones with gradients) and if the it has alpha use 5

T2A` · Sep 26, 2005

I'm pretty sure all the DXT formats have the same image quality and only vary in their alpha channel quality. But that is Hourences above me so I guess I'm wrong.

Starstreams · Sep 26, 2005

Thanks guys,

I don’t know if I’m doing this correct:
For transparency, I created an alpha channel in Photoshop and after modifying the alpha channel I saved it out as a 32-bit TGA file.

The transparency shows up great Unreal but how come when I import the 32-bit image into unreal I am Not prompted to convert it?
Or is that something you have to do manually in the texture browser after you import it ?

Btw, if I save the TGA file from Photoshop as a 24-bit instead of 32-bit the transparency will not work.
It only works as a 32 bit TGA. Is that normal?

Radiosity · Sep 26, 2005

Turns2Ashes - the quality between 3 and 5 is the same, but no way is 1 still as good quality as 3 and 5. 3 is fine for explicit alpha channels (no gradients etc), but 5 should be used for complex (gradients and soft fading etc) alpha channels.

Starstreams - If you're using tga (shouldn't really, working directly with .dds is much better; google for the nvidia dds plugins) then right click the texture and compress it through the menu that pops up in the tex browser.

And yes it's normal for 24bit not to work. 24bit = 8bits red, 8bits blue, 8bits green. 32bit = 8bits red, 8bits blue, 8bits green, 8bits for alpha channel.

Hourences · Sep 26, 2005

And youre not prompted to convert it when you import because you are prolly confused with other UnrealED builds such as the ones pictured on udn. Those do have a convert to prompt upon import.
UT2004 does not, you need to save it as dds right away or manualy rightclick a tex in the tex browser after import and choose convert

And if the only thing you want is some transparancy across the entire texture (so not just at 1 spot or transparancy thats softer or harder at some spots/variation) you might be better off using a shader with blend modes instead of an alpha channel

Starstreams · Sep 26, 2005

Thanks everyone, this stuff is confusing

I’ve had the dds plug in for Photoshop for a while now, just haven’t used it much.

Btw, I always here the term explicit alpha channel, what doses that really mean?

The only reason I was using TGA was because it was mentioned in a lesson and in case I wanted to use these models for other engines later on.

Hourences, if I use a shader with blend modes doesn’t that still require a gray scale image to be put into the shader? How is that any better then an alpha channel, which is gray in the first place?

Kantham · Sep 26, 2005

Im my own eperiments, DXT 5 are always what i want to use for alpha textures, DXT3 Is uter crap for alpha, i don't even use it for anything, i always use DXT 1 for non-alpha textures, and let my ENV effect texture to RGB8 for a better result.

Starstreams · Sep 27, 2005

You know guys; I need to clarify something:

When I say I’m using a TGA file, this is really more for when I’m working with
3D Meshes in 3dsMax but that later will be brought into UT2004.
I’ve heard that TGA is a preferred format for many Max users because it’s not compressed and can be modified later on without data lost.
As far as exporting textures from Photoshop then yes Radiosity, I see your point. I guess it would make sense to save them to (.dds) since it going to have to be converted in unreal later anyway.

Sorry I didn’t clarify this earlier.

Starstreams · Sep 27, 2005

Sorry one quick last reply

The only thing that doesn't make sense still: Many people tell me that I should be using the .dds format.
That's fine, I have the Photoshop plug in for that. However, doses this mean I should still convert the texture from .dds to DXT after it's been imported?

This is where I get confused. Out of two choices, DXT and DDS: I dont' know what format of the two I should be working with from start and at the end of the process?

Hourences · Sep 27, 2005

-No do not convert to dxtc when it already was dds when you imported
-tga works just fine, theres no need to save as dds right away as long as you compress later on in UED
-if the only thing you need is a solid gray texture thats see trough you can use a shader, the shader will be faster because you dont need to save alpha information. In fact you dont need to save anything because you could make a solid gray texture trough material ConstantColor and setting that to gray and filling that in in the diffuse slot of a shader + blendmode translucent/modulate/brighten
You dont need a texture

An alpha texture in Unreal always has a diffuse texture inside it as well btw so therefor your textures shouldnt have alpha if you dont need it to save stuff

And dds and dxtc are the same, dds is the file format, dxtc is the compression name. dds is a texture that has been compressed with dxtc. Its the same

Radiosity · Sep 27, 2005

Hourences said:
tga works just fine, theres no need to save as dds right away as long as you compress later on in UED

I'd have to disagree, simply on the basis that you can't control mipmaps using .tga. Saving directly to dds allows you to precisely control how many mips are generated for each texture/ skin. Plus, I've found that the quality can suffer somewhat when compressing in Ued compared to using the dds plugin to save the tex. Guess it's a matter of personal choice, but I prefer saving to dds wherever possible (unless I'm not compressing a tex for whatever reason, in which case I'll use tga).

Hourences · Sep 27, 2005

The need to manually control things like mipmapping is very minimal and starstreams almost certainly doesnt need that control over it
Most textures default mips are good
Quality loss I never noticed tho it might be possible but itll be a minor differene

dds is a great thing tho, its absolutely not bad to save as dds right away so whatever suits him, its all fine

Starstreams · Sep 27, 2005

Hourences said:
dds and dxtc are the same, dds is the file format, dxtc is the compression name. dds is a texture that has been compressed with dxtc. Its the same

Thank you for clarifying that. I missed that in reading the UDN site.

Hourences said:
--if the only thing you need is a solid gray texture thats see trough you can use a shader,

I was actually doing more soft gradient effect with a soft brush in photoshop.
But, I guess for solid cut outs with shape edges DXT 3 would be the way to go ha? (like in the image I've attached)
again, that would be for a sharp cut out which I guess would be referred to as a mask.

But for a softer smoother/slower fade out into nothingness then DXT 5. I think I got it!

So what doses the diffuse texture have to do with transparency?

Hourences · Sep 28, 2005

I never use 3 for such hard cut out things but in theory 3 should work fine for it yes

Its also better to set the texture to masked in UED instead of alpha when you need such hard cut out edge, it saves cpu

All opacity maps always have a diffuse texture inside them too, thats irrelevant data the engine remembers. If you were to make a seperate opacity map for some ice texture that opacity map will have both a diffuse as an alpha texture inside it..
If you set it up right you can minimize this loss

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