Old to New - DDS texture questions

[tg626]

I have parts that the original author last updated in .24 - so far they have worked fine BUT, with the new fast loading DDS support I'd like to convert the textures to DDS.

I already know how to flip and convert the diffuse TGA textures to DDS BUT there are also XXX_NRM.tga normal maps that I don't quite know what to do with.

Do they need to be greyscaled?

Do they need to be made the alpha layer of the diffuse DDS?

Or do they simply need to be flipped vertically and saved as a DXT1 DDS file?

[Konnor]

They need to be flipped vertically and saved with DXT5nm compression.

Also, check this thread out.

Edited May 12, 2015 by Konnor

[tg626]

Good resource!

I use "DXTBmp" which goes back to my Flight Simulator days - it simply lets you open/save various formats and separates the RGB and Alpha Channels.

For the part I was testing on (Turbo Nisu's big hemispherical tank) I found the following to be true

bigTankCap.dds (made from bigTankCap.tga) needed an alpha channel added to it, which I made mostly black with a small bit of white for the "bands" around the edge of the tank. this was based on a guess of what would look good after looking at the stock X200-16 textures. I'm not sure what the Alpha channel is doing in this texture however.

bigTankCap_NRM.dds (made from bigTankCap_NRM.tga) I had to move the normal map from the RGB to the Alpha (which made it greyscale) and then darken it a touch. I then set the RGB channel to the same grey color found in model001.dds texture of the X200-16 tank.

I used the X200-16 tank as my research subject because Turbo Nisu's "BigTankCap" is *Clearly* intended to match the visual style of the X200 tanks.

DXTBmp refers to the RGB image as "Norm" and the Alpha channel as "Trans".

Based on my experiments so far, I have concluded:

Diffuse DDS:

• 
  [*=1]Norm (RGB) = visible texture image
  [*=1]Trans (Alpha) = ????
  

Normal Map DDS:

• 
  [*=1]Norm (RGB) = Reflection/Shine (is this called "Specualrity?")
  [*=1]Trans (Alpha) = Bump Map
  

[shaw]

Diffuse texture: RGB = colour, alpha = depends on shader: can be transparency, "specularity" or ignored.

Normal map: red = ignored, green = Y component of normal vectors, blue = ignored, alpha = X component. Y is usually also copied to red and blue channels to lessen compression artefacts.

Edited May 12, 2015 by shaw

[tg626]

I assume "X Component" = X Component of normal vectors?

And in any case, can you show me to a resource that will learn me what "Y component of normal vectors" means?

[shaw]

x and y component of per-pixel normal vector relative to surface, e.g. [0, 0, 1] means that normal points straight out of the surface, [1, 0, 0] points in the direction of the first texture coordinate (tangent) and [0, 1, 0] points in the direction of the second texture coordinate (binormal).

Google bump-mapping.