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Won't Fix

Unknown (hidden) 2020.3.X, 2021.3.X, 2022.1.X, 2022.2.X, 2023.1.X

Votes

3

Found in

2020.3.39f1

2021.3.8f1

2022.1.14f1

2022.2.0b6

2023.1.0a8

Issue ID

UUM-12646

Regression

No

Compute Shaders rendering incorrectly when using Vulkan Graphics API for Windows

-

Reproduction steps:
1. Open the user’s attached project
2. Click Edit > Project Settings > Player > Other Settings
3. Switch to Vulkan under Graphics API for Windows
4. Wait for Unity Editor to restart
5. Open the “Assets/instancer/_Scene.unity” scene
6. Enter Play Mode
7. Observe the spheres on the “floor” GameObject

Expected result: No gaps between spheres
Actual result: Gaps between spheres

Reproducible with: 2020.3.39f1, 2021.3.8f1, 2022.1.14f1, 2022.2.0b6, 2023.1.0a8

Reproducible on: Windows 10 Pro 21H2

Note: Does not reproduce when using D3D11/12.

  1. Resolution Note:

    This is not necessarily a bug in Unity but more of a discrepancy between graphics APIs.

    The shader keyword unity_InstanceID is translated into gl_InstanceIndex when using Vulkan and this index does not start from 0 and it implicitly has a base. See https://github.com/KhronosGroup/GLSL/blob/master/extensions/khr/GL_KHR_vulkan_glsl.txt line #1650.

    Therefore, manually adding a base offset to the instance ID in this case would shift the instance ID out of bound and create the 'gap' between LODs.

    (Please refer to my last comment for a fix to the issue)

  2. Resolution Note (2023.1.X):

    Won't fix. This is not necessarily a bug in Unity, but rather part of how Vulkan works.

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