Global SkyAtmosphere and Clouds Issues (Cloud Shadows)

Sampling Cloud Shadows when rendering the Sky Atmosphere can incorrectly assume that the view is located at the planet's North Pole.

This causes distortion in the shadows when using a sphere-shaped Sky Atmosphere and Volumetric Clouds, and the view not at the North Pole.

1. Download the Licensee's test project and open (see addl info URL)
2. Open the level /Game/Planet
3. In the Details Panel, find the Static Mesh Actor "North Pole" and focus on it
4. Observe the shadows that the clouds cast on the Sky Atmosphere (not the mesh) when the camera is inside the atmosphere but above the clouds. They are below the clouds, as you would expect.
5. In the Details Panel, select the Static mesh Actor "Equator", and negate its Y-position.
6. Focus on the "Equator" actor to bring the camera to the equator at the light side of the planet.
7. Bring the camera outside the atmosphere
8. While observing the cloud shadows, slowly bring the camera closer to the "Equator" actor
9. Observe that the moment the camera is within the atmosphere, but above the clouds, the cloud shadows start to swing around violently, and no longer lie nicely under the clouds.
10. Apply the Licensee's changes to the function "IntegrateSingleScatteredLuminance(...)" in SkyAtmosphere.usf
11. Repeat steps 6 - 9, and observe that the Cloud Shadows on the Sky Atmosphere no longer swing around wildly.