The flag is standard – like the enumerant it is a piece of DX spec that has no direct meaning for an OpenGL app and interpreting it mean something in particular.

What we have running now (and this will probably be the shipping impl) is:
– The “complex” surface flag indicate a gamma of 1.8.
– When it is missing, we us a gamma of 2.2.
Why this works:
– The complex flag should never have been set, in hindsight.
– The gamma never should have been 1.8.
So the flag acts as a signal that the file was built using the old version of DDSTool, which is the only tool out there that sets the gamma weirdly, I think.

The value in the DDS file is only for information. It is not passed as enumerant to OpenGL (how?). You can, of course, take this information and use the equivalent OpenGL internal formats (that would be GL_COMPRESSED_SRGB_S3TC_DXT1 et al). But that’s not what I was saying. I was saying, before introducing non-standard flags for x-plane into the DDS files, why not stick with the signaling that already exists, to a maximum extent.

Hrm – those formats probably don’t do what we’re doing – I think they’re like OpenGL – they tell the texture sampler to convert to linear color space on texel fetch. We’re just changing the gamma. We could use those enums…but it might make the toolset we can use even thinner since most Windows encoders will write out DXT5 with a gamma of 2.2 by default.

There are pixel formats explicitly reserved for sRGB encoding, but you need to support the DirectX10 variant of DDS to encode them.

For instance there is DXGI_FORMAT_BC1_UNORM and there is DXGI_FORMAT_BC1_UNORM_SRGB, to specifically denote sRGB color space.

That said, there is a lack of tools do deal with DDS on the mac platform.

I thought the change was 10.6, but the old 1.8 gamma goes back a long time, that’s where X-Plane picked it up.

It’ll probably work – we’ll see soon. If not, we’ll patch it.

It’s not that simple. Sometimes a big issue (next-gen road system) is the sum of a huge number of small issues.

If we’re truly into the ‘fixing the small issues’ development phase, then I am happy enough. I just won’t ask how long the ‘small issues’ list is!