4.1 Regression: Light Linking Influenced Light Tree remains after disabling light linking #119697

New Issue

Alaska · 2024-03-20T14:14:19+01:00

Alaska commented

2024-03-20 14:14:19 +01:00

System Information
Operating system: macOS-14.2.1-arm64-arm-64bit 64 Bits
Graphics card: Metal API Apple M1 Pro 1.2

Blender Version
Broken version: 4.2.0 Alpha, branch: main, commit date: 2024-03-20 11:57, hash: c250b4bd5114
Broken version: 4.1.0 Release Candidate, branch: blender-v4.1-release, commit date: 2024-03-20 07:33, hash: 3c25b079cef5
Worked: 4.0.2

Short description of error:
In Cycles when Light Linking is enabled, and the Light Tree is enabled, part of the Light Tree gets modified to try and reduce noise on the lights that are light linked.

The issue I've found is that this modified Light Tree will remain even after disabling Light Linking. Here is a video demonstrating the issue:

This issue is made obvious by the bug described in #119692. Once that bug is fixed, you will probably still be able to reproduce this, but it will just manifest as noise differences, not artifacts.

Exact steps for others to reproduce the error:

Open the attached .blend file and follow the video above, or follow the written instructions below.
Light Tree Light Linking Remains.blend
Enter Cycles rendered viewport.
Select the object called Light.
Create a light linking collection on Light and add Ground to it.
If #119692 hasn't been fixed yet, then you should see artifacts in the rendered viewport. If it has been fixed, then you will probably see a difference in noise.
Remove the light linked collection from Light. Notice how the artifacts aren't gone.

These artifacts come from the light linking influenced light tree, but light linking is no longer in use, so these artifacts should disappear.

Try changing to solid mode, then rendered mode, disabling and enabling the light tree, and notice none of these steps fix the rendering while the light tree is on.
Add a object to the scene and delete it. Now the inlfuence of light linking on the light tree will be gone.

**System Information** Operating system: macOS-14.2.1-arm64-arm-64bit 64 Bits Graphics card: Metal API Apple M1 Pro 1.2 **Blender Version** Broken version: 4.2.0 Alpha, branch: main, commit date: 2024-03-20 11:57, hash: `c250b4bd5114` Broken version: 4.1.0 Release Candidate, branch: blender-v4.1-release, commit date: 2024-03-20 07:33, hash: `3c25b079cef5` Worked: 4.0.2 **Short description of error:** In Cycles when Light Linking is enabled, and the Light Tree is enabled, part of the Light Tree gets modified to try and reduce noise on the lights that are light linked. The issue I've found is that this modified Light Tree will remain even after disabling Light Linking. Here is a video demonstrating the issue: <video src="/attachments/2896959d-35ed-4d93-a241-b7bc2e73f593" title="Light Tree Light Linking Remains.mp4" controls></video> This issue is made obvious by the bug described in #119692. Once that bug is fixed, you will probably still be able to reproduce this, but it will just manifest as noise differences, not artifacts. **Exact steps for others to reproduce the error:** 1. Open the attached .blend file and follow the video above, or follow the written instructions below. [Light Tree Light Linking Remains.blend](/attachments/c35c782b-f367-4eb6-b5f3-e9ecdb947fc0) 2. Enter Cycles rendered viewport. 3. Select the object called `Light`. 4. Create a light linking collection on `Light` and add `Ground` to it. 5. If #119692 hasn't been fixed yet, then you should see artifacts in the rendered viewport. If it has been fixed, then you will probably see a difference in noise. 6. Remove the light linked collection from `Light`. Notice how the artifacts aren't gone. - These artifacts come from the light linking influenced light tree, but light linking is no longer in use, so these artifacts should disappear. 7. Try changing to solid mode, then rendered mode, disabling and enabling the light tree, and notice none of these steps fix the rendering while the light tree is on. 8. Add a object to the scene and delete it. Now the inlfuence of light linking on the light tree will be gone.

Light Tree Light Linking Remains.blend

927 KiB

Light Tree Light Linking Remains.mp4

2.5 MiB

Alaska added the

labels 2024-03-20 14:14:20 +01:00