[pre-1307] Sector_SetPlaneReflection bug

[MaxED]

When using Sector_SetPlaneReflection action on either floor or ceiling, there's a rendering artifact resembling the shape of the sector the effect is applied to.
The effect is more visible with "r_clearbuffer 1":

Screenshot_Doom_20151023_121228.jpg

[NeoHippo]

This is certainly interesting.

No matter what I do to your map, well within reason, it comes out like this (I changed the ceiling texture)

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no floor with reflection, but showing the artifact.
The player appears to be floating.

Then I duplicated your map from scratch

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identical size, same player location, same script except i called it script 1 with this result

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just as it should be.

I am using GZDB_r2414 and GZDoom_r1307.

[edit]
The bug is also in my map.
See below.

[Rachael]

NeoHippo - your screenshots are staring straight ahead.

I believe MaxED's are staring straight down.

Have you tried staring down in your duplicate?

Also -

The effect is more visible with "r_clearbuffer 1":

Try this, as well.

[NeoHippo]

Have you tried staring down in your duplicate?

Yup, you are right, I should have done that. Because the floor was rendered properly in my example I did not try that.

Not only does the artefact show up in my example as well, it is really pronounced.
And, like MaxED mentioned, the artifact takes on a downscaled version of the sector outline.

My bad.

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The larger the sector, the larger the artefact.

[NeuralStunner]

This is similar to the artifacts that can be seen at the top of the sky sphere. I wonder if the two are related somehow?

[Graf Zahl]

Yes, it's the same effect. Seems that the capping polygon is not drawn into the stencil.

[Graf Zahl]

fixed.