One-sided mirror possible? (impossible)

[Tormentor667]

I am aware of the line special for mirrored lines but is there a way to make the line only mirror one side and not the other?

[Caligari87]

Not sure if it's possible with a double-sided line, although I might be wrong. I thought mirrors had to be one-sided anyway.
Otherwise, I guess you could just do another non-mirrored line on the other side with the correct midtexture, placed very close.

[Tormentor667]

That's the problem actually It needs to be mirroring from one side and see-through from the other

[Graf Zahl]

The mechanics of mirrors pretty much prohibit such a scenario. Remember: Void space behind!

[Tormentor667]

Sad actually, as this feature would make up for some pretty interesting workarounds and hacks.

[Kappes Buur]

Is the void space absolutely required for GZDoom?
I don't seem to have a problem with a short space behind the mirror.

Example map

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as seen with GZDOOM

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Seems to work perfectly, except I had to pull the sides of the mirror forward a bit.
At an extreme angle it clipped a bit.

as seen with ZDOOM

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Everything behind the mirror is reflected to the front of the mirror,
obliterating the mirror effect

[Caligari87]

It doesn't require the full mirror void space like ZDoom does, but it does require a void.

[Graf Zahl]

Precisely. The hardware renderer has better means to clip the geometry but it's not completely immune from problems here. The biggest problem is that sprites get collected per sector so the very least that should be done is to ensure that no sector can be in front and behind the mirror line.

[Kappes Buur]

So, with GZDoom something like this is possible

Example map

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as seen in GZDOOM

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three thin mirrors

[Graf Zahl]

Don't count on that setup being completely glitch free.

[Leonard2]

as seen in GZDOOM

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three thin mirrors

Could you share the map please?

[Kappes Buur]

Could you share the map please?

[Raziel236]

got a mirror of that? XD

[Tormentor667]

So, why isn't it possible then to only make a line one-sided mirroring?

[edward850]

Because you shouldn't be able to see the other side of a mirror in the first place. Even in GZDoom, the lack of void space is not actually considered safe for rendering reflections (even if it is more lax on how much space is actually required, due to it being a view portal, rather than a BSP redraw), and all sorts of weird sorting issues can manifest due to the lack of occlusion. Plane reflections are more easily broken, for example, in situations where if the surrounding area below isn't properly cleared.