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Issue ID




[HDRP] Objects do not get lit and bloomed properly when Fog is enabled

Package: Scriptable Render Pipeline HD


How to reproduce:
1. Open attached project "Fog" and scene "SampleScene"
2. In Hierarchy, select "Sky and Fog Volume"
3. Observe the pillar ("Cube") in Game View
4. In Inspector, disable Volume -> Fog
5. Observe the pillar ("Cube") in Game VIew

Expected result: the pillar is orange and lit on top when Fog is enabled or disabled
Actual result: the pillar is orange and lit on top only when Fog is disabled

Reproducible with: 2018.4.22f1 (4.1.0, 4.10.0) (only if Exponential Fog -> Fog Height Attenuation is 0), 2019.3.11f1 (7.3.1), 2020.1.0b6 (9.0.0), 2020.2.0a8 (8.0.1)
Could not test with: 2017.4 (Package manager was not yet implemented)

  1. Resolution Note:

    Thanks for the bug report. After discussing this with the team, I resolved this case as "by design". Details below.

    First, the height fog component was developed before the PBR sky. There was no concept of a spherical planet, so the world was assumed to reside on an infinite horizontal plane. The height fog component has not been updated since then, primarily for performance reasons.

    Second, the PBR sky features the air and the aerosol components. The aerosol component is the direct replacement for the height fog component. It receives correct illumination from the sky, and correctly accounts for the curvature of the planet.

    Unfortunately, I've been told that it does "not fit super well with the current sky+fog framework", so the contribution of the sky (and thus the fog) is only applied to the skybox, not to the geometry (wheres this works with the height fog component).

    I am being told we are planning to revisit this in the future, but in the meantime, unfortunately, the issue you are experiencing is expected.

Comments (1)

  1. SebLazyWizard

    May 14, 2020 15:35

    I think it's essential, that there should be a mode in which the PBS applies to all geometry as the current separated sky/fog setup will never achieve physically correct results.
    Rendering far away, very high, or even outer space objects is almost impossible with the current setup as I explained in this opening post (Cons section)

    Hopefully that explains the need for a truly "volumetric" atmosphere rendering.

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