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Won't Fix
Votes
1
Found in
2021.3.5f1
2022.1.5f1
2022.2.0a16
Issue ID
UUM-4007
Regression
No
[Android] Texture Format Override is not applied to Lightmaps when Texture Compression is set to Use Player Settings
How to reproduce:
1. Open the user's attached "T1245491_Lightmap.zip" project
2. Set the Platform to Android (File > Build Settings... > Android > Switch Target)
3. Make sure "Texture Compression" is set to "Use Player Settings"
4. Open the player Settings (Edit > Project Settings... > Player)
5. Make sure "Texture compression format" is set to "ASTC"
6. Open Lighting Settings (Window > Rendering > Lighting)
7. Generate Lighting, wait for the Lighting to finish generating
8. In the Project window select Assets > Scenes > SampleScene > Lightmap-0_comp_light
9. In the Inspector observe Android Compression Format
Expected results: The compression format is "RGB(A) Compressed ASTC 4x4 block"
Actual results: The compression format is "RGBA Compressed ETC2 8 bits"
Reproducible with: 2021.3.5f1, 2022.1.4f1, 2022.2.0a16
Could not test with: 2020.3.35f1 and earlier because the Texture Compression Format setting for Android in Player Settings was not yet introduced
Reproduced on:
Windows 10
macOS 12.1 (user's info)
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Resolution Note:
In the provided repro project Lightmap Encoding is set to Normal Quality in Project Settings -> Player Settings. This causes Unity to encode the lightmap data as RGBM (see https://docs.unity3d.com/Manual/Lightmaps-TechnicalInformation.html). Some years ago, we found out that ASTC does not work well with RGBM-encoded data. In fact, the older format ETC2 is better in this case, and therefore Unity chooses this format (more details in this blog post: https://community.arm.com/arm-community-blogs/b/graphics-gaming-and-vr-blog/posts/high-quality-rgbm-texture-compression-with-astc). Therefore this behaviour is actually intensional.
Where applicable, we recommend to use Lightmap Encoding = High Quality. With this setting, Unity will treat lightmaps as HDR data (so it won't use RGBM) and in this case ASTC works great so Unity chooses it, as expected.