House of Fools

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S3TC tools in Unreal Editor
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Starting with version 22, XC_Engine attaches a few new commands to the texture properties window.
These commands are present in the form of BOOL properties under Actions tab.

*Note: You must load XC_Engine into editor for this feature to be available.

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A lesson in dual formatted UT textures:

A texture has two image data 'slots', and they can be of any format (as long as it's supported by the engine).
- P8 = 8bit pallete format (up to 256 colors)
- DXT1 = S3TC format (no alpha transparency)

Your standard UT texture has:
- P8 image data as primary data.

DieHard's textures have
- DXT1 image data as primary data.

UT CD2 textures have
- P8 image data as primary data.
- DXT1 image data as secondary data.

S3TC capable renderers are able to load the secondary data if present, this feature was originally
implemented for the MetalDrv renderer and is now present in updated D3D and OpenGL renderers as well.
This means that these tools allows the user to manipulate individual textures and make them work
in the same fashion as UT CD2 textures would.
Due to format and rendering limitations, masked textures cannot be compressed.

* An example on compression done right:
Had a texture package with 96 textures of 512x512 (P8), size was around 32mb.
I downscaled them to 128x128 and stored the 512x512 data as DXT1 (secondary data) onto the downscaled textures.
The result was a UT CD2 styled package with size 19mb, no loss of quality.


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Short description of these properties/commands:

* CompressDXT1
Compress texture to DXT1 and store in secondary mip data.

* HasCompMips
Indicates if texture has secondary mip data.

* RemoveCompMips
Clears secondary mip data from texture.

* UseMacroTexMips
Copies secondary mip data from 'MacroTexture' into own secondary mip data, clears 'MacroTexture' var.

NOTE: These are not available outside of Editor!

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Standard procedure to manipulating a single texture:

When trying to create a dual-format textures, make sure both are imported in P8 format and that the
high resolution version's (W,H) are 4 times are large as the low resolution one's.

Import the low res version with the name you intend to use, and the high res one with a temporary name
then compress the high res version using 'CompressDXT1'.

Change the low res texture's 'MacroTexture' var to the high res one, then copy the Mip data from the
high res one to the low res using 'UseMacroTexMips'.

Proceed to delete the high res version.

Example:
>> EX: A.pcx (256x256), A_high.pcx (1024x1024)
>> Import A, A_high
>> A_high >> CompressDXT1
>> A >> MacroTexture=A_high
>> A >> UseMacroTexMips
>> A_high >> Delete texture.