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Won't Fix
Votes
0
Found in
2018.4
2019.4
2019.4.0f1
2020.2
2021.1
2021.2
Issue ID
1276188
Regression
No
RenderTarget with premultiplied alpha blending is too bright and does not blend with the background image
How to reproduce:
1. Open the user's attached project
2. Observe the circle In the Game view
Expected result: In the top half of the screen RenderTarget with premultiplied alpha blending blends with the background image
Actual result: In the top half of the screen RenderTarget with premultiplied alpha blending is too bright and does not blend with the background image
Reproducible with: 2018.4.31f1, 2019.4.20f1, 2020.2.4f1, 2021.1.0b6, 2021.2.0a4
Notes:
- Reproducible in Windows Build
-
hazel_koop
Sep 24, 2020 16:19
A forum thread on the subject, with a possible explanation and (somewhat awkward) workaround: https://forum.unity.com/threads/blending-transparent-rendertexture-with-scene-gives-fringing-with-or-without-premultiplied-alpha.966407/
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Resolution Note:
Workaround for Builtin-RP:
In PremultipliedShader, change the line
"Blend One OneMinusSrcAlpha" to "Blend SrcAlpha OneMinusSrcAlpha, One OneMinusSrcAlpha"
OR
add "col.rgb *= col.a;" in fragment function
This bug doesn't reproduce in URP's default transparent shaders.