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CesiumGS / cesium-unreal

Bringing the 3D geospatial ecosystem to Unreal Engine
https://cesium.com/platform/cesium-for-unreal/
Apache License 2.0
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`CesiumSunSky` lights volumetric clouds at night #1341

Open j9liu opened 10 months ago

j9liu commented 10 months ago

Reported on the forum. To reproduce:

  1. Open first level in Cesium samples
  2. Add Volumetric Cloud actor to the scene
  3. Change the Solar Time on CesiumSunSky to sometime in the early morning / night.

image

I did the same with Unreal's built-in SunSky and confirmed that the clouds do not show up during night.

Things I have already tried that have no effect on this:

KieranCoppins commented 8 months ago

I am also experiencing this, however I find at night it lights my models from underneath.

I'm unsure on the implementation of the Cesium SunSky, could the world tile not be casting an "upwards" shadow? Does making it night time make the directional light point upwards?

This occurred for me after upgrading unreal engine to 5.3 from 5.1. And updating to the latest version of Cesium for Unreal, using v2.3.0 binaries.

magiclamb commented 7 months ago

Hi there a fix to this would be fantastic, thanks! :)

wickerman123 commented 2 days ago

Hi,

I've discovered that if you add a SkyAtmosphere component to a CesiumSunSky Actor in the scene via the details panel, then the cloud lighting acts accordingly.

UnrealEditor_4nZiM27uDg UnrealEditor_lep5lXG85N

The only difference is the TransmittanceMinLightElevationAngle which is +90 in CesiumSunSky but -90 in default SunSky and this fix can be replicated by simply changing this default value in CesiumSunSky back to -90.