realtime calculated "reflection" & mirror transparency

[VR_user]

Hello.

I am working on an optic effect similar to a reflection projected on an object.
The difference to a reflection is, that areas of the "mirror" that would "reflect" the scene background should instead be transparent.

For that purpose I created the attached test scene and script.

The result should be that when looking into the mirror like surface,
you should see the objects, with the wall in the background of the reflection.
Actually you see the whole scene reflected in the mirror and the wall is obscured.


Theoretically there are several ways to accomplish the desired effect.

The easiest would be to simply turn the background (viz.clearcolor()) transparent, but it seems like alpha isnt working ?
Alpha for clearcolor isnt documentated but it is recognized and used within viz.py.


I am looking into ways to achieve the desired optical effect.


Kind regards,
Sebastian