Shadow catcher not showing reflections and not bouncing any light back into the scene

[Theverat]

If I remember correctly, in the past, a shadow catcher material showed reflections and bounced light back into the scene. With latest v2.5, this is no longer the case, so it might be a regression.

In the example below, note the missing reflection of the cube in the ground plane, and the missing red color bleed on the cube that should occur.

Scene: shadow_catcher.zip

Shadow catcher on the ground plane disabled:

Enabled:

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[Dade916]

Actually, I have tried v2.4, v2.3 and even v2.2 and they all produce the same results of v2.5. So it is not a regression.

I'm not sure if this should be considered something even possible: the code is currently explicitly written to have pretty much ignore the shadow catcher material but to handle it like a very special case.

If you place another plane under the shadow catcher, it will receive light because it is transmitted where there is no shadow. So obviously I can not both transmit and reflect the same light otherwise I would create energy out of nowhere (i.e. breaking the energy conservation constrain). I have the feeling, the current one is both the correct behavior and, may be, the only consistent one.

[juangea]

Hey David.

Check this thread, specially the first post:

https://devtalk.blender.org/t/lets-finally-fix-the-shadowcatcher/691?u=juangea

The gifs don't show to me, but if you click on them you will see them, in that post the correct behaviour of a shadow catcher is well explained, and it's done with an example with other render engine, I can say that what is shown there is also consistent with Corona Render