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Aaron Ross avatar image
Aaron Ross asked ·

shape node Opaque flag deprecated?

Hi,


Shape node opacity is now automatic. If an object has a shader with non-zero transparency, then that object renders as "non opaque" automatically. That's great because it saves users the hassle of flipping the "Opaque" attribute in each object's shape node.


However, the Opaque attribute is still there, and its state does not change automatically. So we're in a weird situation where the shape node says it's opaque, but the renderer ignores that attribute and renders the shape as "non-opaque". This is confusing for the user. Can we find a better solution for this?


My first idea was for the shape node attribute to change itself automatically, but on reflection I realized that's probably a bad idea, and not practical. Maybe the shape node attribute just needs to go away completely. If the opaque render optimization is automatic, then that manual attribute is irrelevant, and the UI is just creating more problems than it solves.

Thanks

Aaron

renderopacitytransparencyopaque
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Rico Hofmann avatar image
Rico Hofmann answered ·

There is one problem with the automatic. If I want to render a glass with caustics it's always opaque. But in this case the caustics are added to the light which goest trough the non opaque object.
In this case the areas behind the glass object are too bright.

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Aaron Ross avatar image
Aaron Ross answered ·

Great, thanks for the clarification!

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Sebastien Blaineau-Ortega avatar image
Sebastien Blaineau-Ortega answered ·

Hello Aaron,

indeed this opaque flag is simply meant to disappear. We couldn't do it in this release, because there are still use a few use cases where this automatic detection doesn't work (custom shaders being one of them). In that case, the opaque flag value is considered. In most cases, it's simply ignored.

So until this is fully supported, we left this parameter as a backdoor.

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