Transparency rendering black when too far from world origin #84500

New Issue

Bernhard Engstler · 2021-01-07T21:33:25+01:00

Bernhard Engstler commented

2021-01-07 21:33:25 +01:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.89

Blender Version
Broken: version: 2.91.0, branch: master, commit date: 2020-11-25 08:34, hash: 0f45cab862
Worked: I don't know, I tested with 2.83 latest LTS and it's the same problem

Short description of error
Transparent parts of objects (e.g. decals with alpha) which are in front of other objects start to render black when a certain distance away from the world origin.
This might be a corner case, but is a real issue for pre-made assets used in large scale environments.

Cube at 0, 0, 0

Cube at 600, 0, 0

Exact steps for others to reproduce the error
Open the attached blend file and render in cycles. Should render as expected. Move the cube to 600+ meters in X direction, the transparent part renders black. The camera and light is parented to the cube to make it as simple as possible to reproduce.
Interestingly, this does not happen to me when moving the cube only in Y or Z direction. However, other rendering artifacts appear when placing the cube at 5000 m in Z axis (perhaps a bit extreme).

The decal is about 0.001 m away from the cube, and the further it is away from the cube, the further away I can move the cube away from the world origin before this problem happens. I'm aware that camera clip start and end influences z-fighting, but I'm don't know what it has to do with the position relative to the world origin?

DecalTest.blend

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.89 **Blender Version** Broken: version: 2.91.0, branch: master, commit date: 2020-11-25 08:34, hash: `0f45cab862` Worked: I don't know, I tested with 2.83 latest LTS and it's the same problem **Short description of error** Transparent parts of objects (e.g. decals with alpha) which are in front of other objects start to render black when a certain distance away from the world origin. This might be a corner case, but is a real issue for pre-made assets used in large scale environments. Cube at 0, 0, 0 ![image.png](https://archive.blender.org/developer/F9554697/image.png) Cube at 600, 0, 0 ![image.png](https://archive.blender.org/developer/F9554699/image.png) **Exact steps for others to reproduce the error** Open the attached blend file and render in cycles. Should render as expected. Move the cube to 600+ meters in X direction, the transparent part renders black. The camera and light is parented to the cube to make it as simple as possible to reproduce. Interestingly, this does not happen to me when moving the cube only in Y or Z direction. However, other rendering artifacts appear when placing the cube at 5000 m in Z axis (perhaps a bit extreme). The decal is about 0.001 m away from the cube, and the further it is away from the cube, the further away I can move the cube away from the world origin before this problem happens. I'm aware that camera clip start and end influences z-fighting, but I'm don't know what it has to do with the position relative to the world origin? [DecalTest.blend](https://archive.blender.org/developer/F9554702/DecalTest.blend)

Bernhard Engstler commented

2021-01-07 21:33:25 +01:00

Added subscriber: @B_Engstler