[JohnnyS]

Hi gpz, what settings/compression do you recommend for exporting textures with no alpha channel?

[gpz]

Those can go to DXT1 as well.

[JohnnyS]

OK, thanks for the info.

[disc]

DXT1- for non alpha, or 1 bit alpha (used with texdiff) textures
DXT3- for textures with alpha where the alpha gradient precision is not so necessary.
DXT5 for textures with alpha, where the fine gradients in alpha are needed
mipmap is always needed, unless if the texture appears in fixed distance from camera (cab textures, UI textures)

[gpz]

 disc, on 09 February 2014 - 11:22 AM, said:

DXT3- for textures with alpha where the alpha gradient precision is not so necessary.

The only reason of DXT3 being less precise in alpha than DXT5 is, that it has a dedicated alpha value 0 and 255, unlike DXT5. While in DXT5 the alpha 0 might be 5, or the alpha 255 might be 250. This is the reason the preferred format for textures with sharp cutout should be DXT3.

[Csantucci]

 disc, on 09 February 2014 - 11:04 AM, said:

Why no mipmap?

Because I'm no expert in graphics :pardon:

[nicober]

Hi!

I made some tests to convert TGA files to DDS format with various tools. I reskinned a SLI/SD40ACE locomotive in NS Heritage NY-Central colors.

The Textures:
- NS_SD70ACEa-NY_Central-1066.ace - No Alpha-Chanel ---------------- Use DXT-1
- NS_SD70ACEb-NY_Central-1066.ace - Simple Alpha-chanel ---------------- Use DXT-3
- SD70ACe-interior.ace - No Alpha-Chanel ---------------- Use DXT-1
- SD70M-windows.ace - Subtile Alpha-Chanel ---------------- Use DXT-5

Tools:
- Plug-ins Photoshop: Everything seems working. The display in OR is very good.
- Plug-ins The Gimp: Everything seems working. The display in OR is very good.
- Paint.Net : Everything seems working. The display in OR is very good in a close view of the loco but I encountered a very bad displaying when I moves the camera a little bit faraway of the loco.
Note: In Paint.Net the DXT-1 No-Alpha option doesn't exist. I found only the DXT-1 (Opaque/1bit Alpha) In the 2 other Plug-ins, we have the choice between DXT-1 No-Alpha or DXT-1 1 bit Alpha. I don't know if this limitation in Paint.Net cause this problem with the position of the camera.


The display with the camera close to the locomotive. Look OK.


The display with the camera is a little bit araway of the locomotive. Look Ugly.

What's the difference between the compression DXT-1 No-Alpha and DXT-1 1Bit Alpha?

I tried also XnView to convert TGA files to DDS format but it can convert only in DXT-1 No-Alpha but works fine.

Cheers!

[gpz]

 nicober, on 10 February 2014 - 08:26 PM, said:

The display with the camera is a little bit araway of the locomotive. Look Ugly.
What's the difference between the compression DXT-1 No-Alpha and DXT-1 1Bit Alpha?

It looks like the same effect that Carlo got with Paint.net. Must be a bug.
For DXT compression read this article.

[James Ross]

 nicober, on 10 February 2014 - 08:26 PM, said:

- Paint.Net : Everything seems working. The display in OR is very good in a close view of the loco but I encountered a very bad displaying when I moves the camera a little bit faraway of the loco.
Note: In Paint.Net the DXT-1 No-Alpha option doesn't exist. I found only the DXT-1 (Opaque/1bit Alpha) In the 2 other Plug-ins, we have the choice between DXT-1 No-Alpha or DXT-1 1 bit Alpha. I don't know if this limitation in Paint.Net cause this problem with the position of the camera.

DXT1 supports 1bit alpha, but when a pixel group (it saves groups of 4x4 pixels) has alpha it has less fidelity for the colours, so some tools offer the option to discard alpha and always get the best colours.

The issue when you move the camera away definitely appears to be a Paint.NET DDS bug with the mipmaps.

[disc]

Try to use gimp with dds plugin that doesn't have such problems.