Material override with 'Preserve Bump' (either in the main UI or as a pass)

[pokoy]

I already requested this, it was moved to resolved requests, I wanted to update my request but the forum suggested to start a new request so here it is.

In reference to my original request:
https://forum.corona-renderer.com/index.php/topic,6753.0.html

I am facing a situation where in order to get some useful passes I'd need to replace 500+ materials only to achieve a plain reflection pass with preserved bump.

Can we - please! - have this added as an option in the Mtl Override section. Since the original reply to my request stated it would clutter the UI (besides that it's not easy to implement), you could easily solve this that way:
Preserve: [] Displacement [] Bump

I know there have been requests to add an transparency/opacity switch to this section to so maybe all could be done in one go...? If this is too much for the main UI, maybe adding an override pass would be a viable solution.

Preserving bump is really common and needed in an mtl override option, please consider implementing it.

[Ludvik Koutny]

Is there any reason why you don't use reflection render element for reflection pass?

[pokoy]

I'd like to have control over the material, basically other properties than what you get from the materials' original reflection properties, for example a 'dust' layer with very low glossiness, other example would be a clay pass, of course.

[Ludvik Koutny]

I guess it makes sense. We have displacement preservation to keep overriden output same as original one silhouette-wise, which means we will also need to preserve opacity of the materials, which is already a shading effect, so there's no reason not to have bump there as well.

The question is what happens if material in override slot already has bump map? I think it would be best that if preservation of bump was enabled, bump map of material in override slot would be ignored.

[pokoy]

I guess it makes sense. We have displacement preservation to keep overriden output same as original one silhouette-wise, which means we will also need to preserve opacity of the materials, which is already a shading effect, so there's no reason not to have bump there as well.

The question is what happens if material in override slot already has bump map? I think it would be best that if preservation of bump was enabled, bump map of material in override slot would be ignored.

Yes, in that case bump of the OR mat would have to be ignored.

I guess what makes this so important is that it's a quick way to control a lot of the final look where you rely on the level of detail being defined by the bump effect. No doubt, preserve displacement is great to have but with many scenes you just can't afford to use displacement (or it's plain impractical) so bump is the only way to introduce the needed detail. Think... airplanes with a lot of bump surface details ;)

[Ludvik Koutny]

Think... airplanes with a lot of bump surface details ;)

Yup, that's exactly what i thought about ;) Ondra said it will not be easy but it is possible. It's probably not gonna be very soon, but it's a valid request that should be implemented at some point.

[pokoy]

That's great! I'll have to find a workaround for the time being, but glad to hear it's been approved.

I just realized it should also include normal maps, not just bump - but you're probably aware of that ;)

[Ludvik Koutny]

That's great! I'll have to find a workaround for the time being, but glad to hear it's been approved.

I just realized it should also include normal maps, not just bump - but you're probably aware of that ;)

I expect it will just preserve whatever ends up in a bump slot, be it normal map or heightmap :)

But I would not be 100% sure about approval. It always depends on Ondra in the end.

[pokoy]

I need to improve my telepathy skills then!

[pokoy]

I have a feeling that this one will drown because it's been requested only by me so far. Bumping this thread for dev awareness. If it's possible for 1.4 - please add this, it will be more useful than most people think (I hope). Thanks!

[Ondra]

see https://forum.corona-renderer.com/index.php?topic=11864.new#new