[BUG] Render EXR is not multilayer and issues with preview the multilayer EXR render result

[rabits]

Issue description:

For some reason BlendNet is not saving the render result as multilayer EXR file - it seems like the regular one layer EXR.

Environment:

• Application version: 0.2.0
• Blender client version: 2.80, 2.81, 2.82a, 2.83.5, 2.90.0
• Blender worker version: 2.80, 2.81, 2.82a, 2.83.0, 2.90.0
• OS: Ubuntu 18.04, Ubuntu 20.04

Steps to reproduce:

1. Run Blender
2. Open test project
3. Run manager on any provider
4. Run image task
5. Check the completed result exr

Expected behavior

Seems something is wrong with the save parameters, so it should use OPEN_EXR_MULTILAYER for sure

[rabits]

Hmmm, not sure how that's possible - but previously it worked just fine... Maybe I'm missing something...

[rabits]

Still don't understand how I can miss such an issue, seems it's a known one: https://developer.blender.org/T71087

Found workaround that should work - use write_still for render call.

[rabits]

Ok, it's working, but now the result image is not opening in preview in Addon:

INFO: Render status: , testproject-2009040819-32-VHY: COMPLETED
INFO: Render status: Got the final render! | Task render time: 1m17s, testproject-2009040819-32-VHY: COMPLETED
Error: can't process EXR multilayer file
IMB_ibImageFromMemory: unknown fileformat (/home/user/Work/state-of-the-art/BlendNet.wiki/blendnet-test-project-2.82-v0.2/out/testproject-200904081
9-32-VHY.exr)
Traceback (most recent call last):
  File "/home/user/.config/blender/2.83/scripts/addons/blendnet/__init__.py", line 1507, in render
    result.layers[0].load_from_file(update_render)
RuntimeError: Error: RE_layer_load_from_file: failed to load '/home/user/Work/state-of-the-art/BlendNet.wiki/blendnet-test-project-2.82-v0.2/out/te
stproject-2009040819-32-VHY.exr'

[rabits]

If there is multilayer I need to use just result.load_from_file to load result properly. But, new interesting issue:

warning, channel with no rect set View Layer.Debug Render Time.X
warning, channel with no rect set View Layer.Denoising Albedo.B
warning, channel with no rect set View Layer.Denoising Albedo.G
warning, channel with no rect set View Layer.Denoising Albedo.R
warning, channel with no rect set View Layer.Denoising Depth.Z
warning, channel with no rect set View Layer.Denoising Intensity.X
warning, channel with no rect set View Layer.Denoising Normal.X
warning, channel with no rect set View Layer.Denoising Normal.Y
warning, channel with no rect set View Layer.Denoising Normal.Z
warning, channel with no rect set View Layer.Denoising Shadowing.X
warning, channel with no rect set View Layer.Denoising Variance.B
warning, channel with no rect set View Layer.Denoising Variance.G
warning, channel with no rect set View Layer.Denoising Variance.R
warning, channel with no rect set View Layer.Noisy Image.A
warning, channel with no rect set View Layer.Noisy Image.B
warning, channel with no rect set View Layer.Noisy Image.G
warning, channel with no rect set View Layer.Noisy Image.R

So those layers are not loading into the Render Result image... Looks like the issue: https://developer.blender.org/T21410 , but actually not so critical:

• The actual EXR result containing all the required layers and could be loaded properly via the regular compositing image node or directly to blender via usual Image Editor UI
• When #33 will move the compositing to the Manager side - there will be not much sense to actually load the Render Result image properly, preview will be just enough.

[rabits]

33 is covering the issue just enough to close this one.

[rabits]

This issue, actually, affecting the agent render process - because if it's not completed (agent is going to be terminated or just stopped) there is no way to receive the render result - it will just be not saved.