Doomsday Engine

Apologies for arguably reporting several things in one report (I got carried away writing).

Something I'd like to do in a future version is redesign how the sky-glow is sampled. Presently this works by evaluating the colors of the sky textures at load time. This is fine for the skydome where we have prior knowledge about the geometry, but model skies can't be dealt with in the same way.

The solution I'd like to use here is to render the sky to a very low quality cube map and sample the sky-glow color using this instead. That way, it'll work independent of the sky geometry and can be sampled in "real time" (in reality, a delay of a few tics wouldn't hurt if the sampling results were animated with interpolation).

Naturally there are other benefits to using a cube map. Specifically, we'd be able to determine if there is a strong light source in the sky and determine an approximate origin vector in 3D space. Once such a vector is obtained we'd be able to do more interesting lighting in outdoor areas.

I was indeed specifying -1 in a group def. As I wrote above, I wasn't sure if it was a bug or a never supported feature.

I simply wanted a standard sky texture to change into another on it's own, over the course of a map.

I see. Yeah a duration of Group.Flat/Texture.Tics = -1 has never been supported as there is no "infinite" concept at Group level. At the least the parser should catch this and log a warning...

It sounds like you're trying to set things up so that there is a one-time animation which when complete, switches to a separate looped animation? If so then this is far beyond the scope of what a Group is intended for.

Once support for multi-layered Materials has been completed we can then revise the sky dome renderer to use the full material system feature set, removing the special case layer mechanic used for sky layers. At which point, scripting up sky material changes as you'd like should be more doable.