Q about Indigo rebuilding scene

[FakeShamus]

Hi, I am wondering why in some cases Indigo seems to unnecessarily re-build the scene while adjusting a material, for example. I can understand when changing a displacement parameter or something that effects the geometry and a mesh has to be recalculated, but I am getting re-building when tweaking bump parameters, or adding an image texture, for example, which seems like it has nothing to do with the actual scene geometry. I'm not sure this is a bug, but it does seem like more recent Indigo versions are doing this when earlier ones didn't. And on large scenes it's definitely a burden to wait through that process every time Indigo decides to rebuild things.
This is on 4.0.50 running on OSX 10.11.6, by the way...
Thx!

[Originalplan®]

Hmmm.... i don't think thats a bug.
Well if you check the above on a New Material inside Indigo (like opening a new) you would see that (CPU-GPU)
will rebuild when you make changes...even on Mat Prev window. But that said it is logical since > you made a change. Like editing Bump from: 0,0003 > 0,0004 is still a change even when the diff isn't super noticeable.

[Oscar J]

Bump map changes shouldn't cause GPU rebuilds I think?

Rebuilds take a lot longer on Mac because of an OS bug.

[Zom-B]

...but I am getting re-building when tweaking bump parameters, or adding an image texture...

In OpenCL rendering a shader needs to be recompiled on change for the GPU, on a NVIDIA card atm this process can take more time then on AMD cards.
Or are you in CPU render mode? If yes, you maybe could upload a minimalistic example file, since that should not happen at all as Oscar already pointed out

[FakeShamus]

Yeah. Should have mentioned, this is just using CPU. And I'm not talking about just changing the material and the render restarting, that makes sense, of course. It's the entire scene building process restarting, which I don't think used to happen with superficial shader changes. Should also add that it seems inconsistent and doesn't happen every time, so it's definitely feeling buggy.

[OnoSendai]

Can you post a PIGM of the material that when changed, is causing the scene to be rebuilt? Or can you email us the scene?

[FakeShamus]

Yeah, I'll try to recreate it and post here later

[FakeShamus]

ok, so this doesn't seem specific to any particular scene. I just tried with a brand new basic diffuse material and added subdivision to the preview sphere, 4 levels. the re-calculation seems to happen with almost any change to the material properties. even just changing the name of the material causes Indigo to recalculate the subdivision, build the scene, etc.

Now, I'm assuming this shouldn't happen unless the actual geometry of the scene is changed, but maybe I'm wrong? with many subdivided objects it really slows things down.

[FakeShamus]

ok, so a little more experimenting. the slowdown only really begins when subdivision and displacement are added on an object. as I mentioned, even just changing the name of the material will cause the subdivision and displacement to be recalculated every time. before any displacement is added, the subdivision seems to work fine, it will calculate once and then you can change other variables, add bump, roughness, change albedo and image textures, material name, all without a new calculation. but once displacement is added the recalculating starts with every change you make. then, even when you try removing the displacement channel, untick all displacement check boxes, the problem persists.

I just tried this with the new release, 4.0.52 and it behaves the same...

[FakeShamus]

Hi, I'm bumping this cause it is a persistent and annoying issue...
is anyone else experiencing it like I am? I change the name of a material and every keystroke as I type the material name restarts the render - this doesn't make sense.

[arc en ciel]

yes I experienced that. I've adapted my workflow and doing adjustement for a material on a single (lowpoly) object with correct lighting and a minimal environnement, so the restarts are faster. And when the material is ready I record the material's settings inside 3D host app or I save the material in igs/pigs format and link it using external.
it's not a big issue in my opinion, but ... an annoying issue, I agree

[OnoSendai]

Thanks for bug report FakeShamus, I think I have found and fixed this. I'll PM you a build to test.