Mirrored objects render black when using the Bevel Node #61103

New Issue

Sebastian Koenig · 2019-02-01T16:54:48+01:00

Sebastian Koenig commented

2019-02-01 16:54:48 +01:00

System Information
Operating system: elementaryOS 0.4.1
Graphics card: GTX1080

Blender Version
Broken: 2.80, 7b05b2564d

Short description of error
Objects that use the Bevel Node render almost black. Happens to regular objects as well as Collection Instances. But only on F12! The error is not visible in Viewport Rendering.
Here's how it looks in the viewport:

And this is how it looks when rendered (F12):

Happens also in 2.79 (master)
Exact steps for others to reproduce the error
Open this file and compare viewport render and F12:
bevel_mirror.blend

**System Information** Operating system: elementaryOS 0.4.1 Graphics card: GTX1080 **Blender Version** Broken: 2.80, 7b05b2564d8 **Short description of error** Objects that use the Bevel Node render almost black. Happens to regular objects as well as Collection Instances. But only on F12! The error is not visible in Viewport Rendering. Here's how it looks in the viewport: ![bevel_mirror_viewport.jpeg](https://archive.blender.org/developer/F6476701/bevel_mirror_viewport.jpeg) And this is how it looks when rendered (F12): ![bevel_mirror_f12.jpeg](https://archive.blender.org/developer/F6476708/bevel_mirror_f12.jpeg) Happens also in 2.79 (master) **Exact steps for others to reproduce the error** Open this file and compare viewport render and F12: [bevel_mirror.blend](https://archive.blender.org/developer/F6476732/bevel_mirror.blend)

Sebastian Koenig commented

2019-02-01 16:54:48 +01:00

Added subscriber: @sebastian_k

Brecht Van Lommel was assigned by Sebastian Koenig

2019-02-01 16:55:18 +01:00

Tim Stullich commented

2019-03-05 12:11:26 +01:00

Added subscriber: @tstullich

Tim Stullich commented

2019-03-06 01:06:55 +01:00

Hi, I am interested in trying to fix this issue. I was wondering in which files would I need to look in order to start tracking down the source of the bug?

Brecht Van Lommel commented

2019-03-06 12:59:03 +01:00

The bevel shader code is in intern/cycles/kernel/svm/svm_bevel.h.

The bevel shader code is in `intern/cycles/kernel/svm/svm_bevel.h`.

Tim Stullich commented

2019-03-08 19:00:50 +01:00

Ok, so I started taking a look at the shader code but I am having a hard time understanding it all, even with the reference paper in the comments. Is there a way to debug the shader code when it is running?

Brecht Van Lommel commented

2019-03-08 19:22:50 +01:00

You can use a debugger to set a breakpoint on this function and step through the code. Which one depends on your development environment, it's not really a Blender specific thing.

This is not the easiest bug to start with though, if you're just getting start with Blender development you might want to pick an easier bug.

You can use a debugger to set a breakpoint on this function and step through the code. Which one depends on your development environment, it's not really a Blender specific thing. This is not the easiest bug to start with though, if you're just getting start with Blender development you might want to pick an easier bug.

Tim Stullich commented

2019-03-08 19:34:36 +01:00

Yeah, I am thinking I might be a little in over my head with this bug, although it has been fun reading up on MIS and BSSRDF concepts and getting to know the code base.

Do you have a suggestion for an easier bug to start with? I had asked in the IRC channel for one and this one was suggested to me as a starter.

Yeah, I am thinking I might be a little in over my head with this bug, although it has been fun reading up on MIS and BSSRDF concepts and getting to know the code base. Do you have a suggestion for an easier bug to start with? I had asked in the IRC channel for one and this one was suggested to me as a starter.

Sebastian Koenig commented

2019-03-08 22:02:41 +01:00

@tstullich so sorry to have put you on this, I really thought this would be an easy one , especially because it works fine in preview rendering.... I better shut up next time :)