Cycles: Light and shadow linking does not work when you link an object to itself. #108363

New Issue

Alaska · 2023-05-28T03:59:20+02:00

Alaska commented

2023-05-28 03:59:20 +02:00

System Information
Operating system: Windows-10-10.0.22621-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 4090/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 532.03

Blender Version
Broken version: 4.0.0 Alpha, branch: main, commit date: 2023-05-27 16:27, hash: 0a004fbad460
Worked: NA

Short description of error
If you light/shadow link an object to itself, then the light/shadow link will not function properly.

Exact steps for others to reproduce the error

Change the render engine to Cycles.
Create a collection, and in it place two objects. I will call them "cube" and "ground".
On the "cube" object add two materials. A diffuse material and a emissive material. Assign the emissive material to one face and the diffuse material to the rest.
Enter the rendered viewport.
Select the cube, in the Object Properties tab under Shading -> Shadow Linking select the collection that the cube is in.
Now notice that the light from the cube is "leaking" through the cube and onto the ground. This shouldn't be happening based on the shadow linking properties selected. Instead, because we shadow linked the object to itself, the cube should be casting shadows, but it doesn't.
The same sort of issue applies to light linking.

Here's a video of the issue, at the end I separate the emissive part of the cube into a separate object to show case how I expect the shadow linking to work:
Incorrect self light-shadow linking.mp4

And here's a .blend file with steps 1-3 done:
Self Light-Shadow Linking Issue.blend

**System Information** Operating system: Windows-10-10.0.22621-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 4090/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 532.03 **Blender Version** Broken version: 4.0.0 Alpha, branch: main, commit date: 2023-05-27 16:27, hash: `0a004fbad460` Worked: NA **Short description of error** If you light/shadow link an object to itself, then the light/shadow link will not function properly. **Exact steps for others to reproduce the error** 1. Change the render engine to Cycles. 2. Create a collection, and in it place two objects. I will call them "cube" and "ground". 3. On the "cube" object add two materials. A diffuse material and a emissive material. Assign the emissive material to one face and the diffuse material to the rest. 4. Enter the rendered viewport. 5. Select the cube, in the `Object Properties` tab under `Shading -> Shadow Linking` select the collection that the cube is in. 6. Now notice that the light from the cube is "leaking" through the cube and onto the ground. This shouldn't be happening based on the shadow linking properties selected. Instead, because we shadow linked the object to itself, the cube should be casting shadows, but it doesn't. 7. The same sort of issue applies to light linking. Here's a video of the issue, at the end I separate the emissive part of the cube into a separate object to show case how I expect the shadow linking to work: [Incorrect self light-shadow linking.mp4](/attachments/6eb210e1-7a87-4777-94e1-9e93dda2b18f) And here's a .blend file with steps 1-3 done: [Self Light-Shadow Linking Issue.blend](/attachments/55e85c70-03dc-4028-a1ae-a4781b49ccf1)

Self Light-Shadow Linking Issue.blend

876 KiB

Incorrect self light-shadow linking.mp4

1.9 MiB

Alaska added the

labels 2023-05-28 03:59:21 +02:00