Bug [URP][Quest 2] Camera snaps and stops rendering subtractive shadows.

Unity Version: 2020.3.18f / 2020.3.43f
URP Version: 10.10.1
Platform: Quest 2
Lighting: Mixed (Subtractive)

When the game starts, shadows appear fine, but they seem to disappear (and never come back) when the player looks away from the shadow-casting mesh. Once the bug is triggered, the camera will not see shadows from any mesh.

More info:
- The bug seems preventable if I keep a shadow-casting mesh in the camera's view.
- The bug also happens if the mesh gameObject is disabled for one frame. The shadows never come back even if the gameObject is enabled.
- If I start the scene with Soft shadows and trigger the bug, the bugged camera can actually render shadows again if I changed the shadow type to Hard (the shadows will disappear if I change it back to Soft). If I start the scene with Hard shadows, the bug can happen vice versa.

- I breakpoint-debugged the light, the camera, the material, the shadow color, the quality settings, and couldn't find anything unusual--all the settings and properties are still fine.
- I used RenderDoc, and the captured frame still has shadows, even though there is no shadow in the headset / screenshot / video capture.

- The bug is not reproducible whatsoever on the editor (Rift S).
- The bug is only reproducible 70% of the time on Quest 2 (not sure why).
- Real-time shadows on dynamic meshes still appear fine even after the bug happens to subtractive shadows on baked meshes.

Any help will be appreciated.

 

Whaaat, this seems like the start of a horror game with the shadow suddenly away.

Anyhow, few questions:

- are you using vulkan or opengl?
- if vulkan, do you use graphics jobs?
- did you try disabling the optimizations in the Oculus XR plugin for android?
- did you try switching multiview/multipass?
- does this happen in the latest 2020 lts?


Edit:
Is it possible shadows are disabled in the URP asset used for android?
If so, maybe it is switching from baked to realtime lighting because something changed and realtime lights aren't possible because theyre disabled?

 

- I'm using OpenGL.
- I've tried Multiview/Multipass, disabling Low Overhead Mode (GLES), Phase Sync, Subsampled Layout, etc. The bug is still reproducible.
- I've tried upgrading to the latest 2020.3.43, and the bug is still reproducible.

 

I added another video with a new rotating camera using RenderTexture.
I used to be able to trigger the bug on one camera while the other camera still sees shadows, but now the bug seems to happen to both cameras simultaneously.

 

I've attached & debugged the running process. The properties/settings about the light, the material, the camera, and the URP pipeline asset didn't change after the bug happens. Besides, if I change the shadow type (from Soft to Hard or vice versa), the shadows appear again (but disappear if I change the shadow type back).

It feels like when the bug happens, the renderer stops rendering the type (Soft/Hard) of subtractive shadows I started with.

Code (CSharp):

1. UnityEngine.Rendering.GraphicsSettings.currentRenderPipeline
2. "UniversalRP-HighQuality (UnityEngine.Rendering.Universal.UniversalRenderPipelineAsset)"
3.     base: "UniversalRP-HighQuality (UnityEngine.Rendering.Universal.UniversalRenderPipelineAsset)"
4.     additionalLightsRenderingMode: Disabled
5.     additionalLightsShadowmapResolution: 2048
6.     cascade2Split: 0.25
7.     cascade3Split: "(0.1, 0.3)"
8.     cascade4Split: "(0.1, 0.1, 0.3)"
9.     colorGradingLutSize: 32
10.     colorGradingMode: LowDynamicRange
11.     default2DMaterial: null
12.     defaultLineMaterial: null
13.     defaultMaterial: null
14.     defaultParticleMaterial: null
15.     defaultShader: "Universal Render Pipeline/Lit (UnityEngine.Shader)"
16.     defaultTerrainMaterial: null
17.     defaultUIETC1SupportedMaterial: null
18.     defaultUIMaterial: null
19.     defaultUIOverdrawMaterial: null
20.     k_AssetPreviousVersion: 5
21.     k_AssetVersion: 6
22.     m_AdditionalLightShadowsSupported: true
23.     m_AdditionalLightsPerObjectLimit: 4
24.     m_AdditionalLightsRenderingMode: Disabled
25.     m_AdditionalLightsShadowmapResolution: _2048
26.     m_Cascade2Split: 0.25
27.     m_Cascade3Split: "(0.1, 0.3)"
28.     m_Cascade4Split: "(0.1, 0.1, 0.3)"
29.     m_ColorGradingLutSize: 32
30.     m_ColorGradingMode: LowDynamicRange
31.     m_DefaultRendererIndex: 0
32.     m_DefaultShader: "Universal Render Pipeline/Lit (UnityEngine.Shader)"
33.     m_LocalShadowsAtlasResolution: _256
34.     m_LocalShadowsSupported: false
35.     m_MSAA: Disabled
36.     m_MainLightRenderingMode: PerPixel
37.     m_MainLightShadowmapResolution: _2048
38.     m_MainLightShadowsSupported: true
39.     m_MaxPixelLights: 0
40.     m_MixedLightingSupported: true
41.     m_OpaqueDownsampling: None
42.     m_RenderScale: 1
43.     m_RendererData: null
44.     m_RendererDataList: UnityEngine.Rendering.Universal.ScriptableRendererData[1]
45.     m_RendererType: ForwardRenderer
46.     m_Renderers: UnityEngine.Rendering.Universal.ScriptableRenderer[1]
47.     m_RequireDepthTexture: false
48.     m_RequireOpaqueTexture: false
49.     m_ShaderVariantLogLevel: Disabled
50.     m_ShadowAtlasResolution: _256
51.     m_ShadowCascadeCount: 1
52.     m_ShadowDepthBias: 1
53.     m_ShadowDistance: 20
54.     m_ShadowNormalBias: 0
55.     m_ShadowType: HardShadows
56.     m_SoftShadowsSupported: true
57.     m_StoreActionsOptimization: Auto
58.     m_SupportsDynamicBatching: true
59.     m_SupportsHDR: false
60.     m_SupportsTerrainHoles: false
61.     m_UseAdaptivePerformance: true
62.     m_UseSRPBatcher: true
63.     m_VolumeFrameworkUpdateMode: ViaScripting
64.     mainLightRenderingMode: PerPixel
65.     mainLightShadowmapResolution: 2048
66.     maxAdditionalLightsCount: 4
67.     msaaSampleCount: 1
68.     opaqueDownsampling: None
69.     renderScale: 1
70.     rendererIndexList: int[2]
71.     scriptableRenderer: {UnityEngine.Rendering.Universal.ForwardRenderer}
72.     scriptableRendererData: "ForwardRenderer (UnityEngine.Rendering.Universal.ForwardRendererData)"
73.     shaderVariantLogLevel: Disabled
74.     shadowCascadeCount: 1
75.     shadowDepthBias: 1
76.     shadowDistance: 20
77.     shadowNormalBias: 0
78.     storeActionsOptimization: Auto
79.     supportsAdditionalLightShadows: true
80.     supportsCameraDepthTexture: false
81.     supportsCameraOpaqueTexture: false
82.     supportsDynamicBatching: true
83.     supportsHDR: false
84.     supportsMainLightShadows: true
85.     supportsMixedLighting: true
86.     supportsSoftShadows: true
87.     supportsTerrainHoles: false
88.     useAdaptivePerformance: true
89.     useSRPBatcher: true
90.     volumeFrameworkUpdateMode: ViaScripting

 

Try the latest lts version and of that doesn't fix it make a bug report

 

The bug has been created on Unity Issue Tracker:
https://issuetracker.unity3d.com/is...btractive-shadows-when-reentering-camera-view