Arena

So the game takes place in the atmosphere above Venus.

Ground radius: 6,051.8 km
Scale height: 15.9 km
Surface gravity: 0.91 G
Surface pressure: 92 bar
Surface visibility: ~3 km
Kármán line: ~165 km

ExponentialHeightFog - basically need one setting for below the upper cloud layer (BCL) and one for above the upper cloud layer (ACL) ... or maybe we need to modify it as we change altitude through C++ ... I am not entirely clear yet except that the exponential height fog is much more realistic than what we used to do ... we should not be able to see the ground above ~3 km? Should not be able to see the lower cloud layer until what altitude?

Tune the 50 km layer so large structures are readable at 5–10 km, with the far horizon fading out by 15–25 km.

Modern reviews place the lower cloud layer at about 47.5–50.5 km, and probe data show a sharp increase in extinction just below 50 km, with the lower cloud layer having visible optical depth around 6–12 in some measurements.

Exponential Height Fog and Altitude Adjustments

The exponential height fog represents how atmospheric density changes with altitude. To achieve specific visibility targets at different heights:

Start by setting the fog density at the surface level. Adjust this until you achieve, for example, 3 kilometers of visibility near the ground.

Next, adjust the height falloff parameter. This controls how rapidly the fog thins out as you go higher. Tune the falloff until you achieve about 10 kilometers of visibility at around 50 kilometers altitude.

If the natural exponential transition isn’t layered enough for your needs—for instance, if you want certain altitudes to be foggier or clearer—then you can dynamically adjust density or falloff at different altitude ranges. By tweaking fog parameters in steps, you can approximate a layered atmospheric profile.

Static Directional Light (Sun)

In our scenario, Venus’s day is extremely long. Over the course of a gameplay session, the sun’s movement would be imperceptible. Thus, we treat the sun’s directional light as static.

The sun’s light itself is pure white; any color shift we perceive (like yellow) is due to atmospheric scattering. On Venus, the color of sunlight will be handled by the Sky Atmosphere actor, which manages how light is scattered through the planet’s atmosphere.

Keeping the sun static simplifies computations. With a stationary sun, lighting can be baked for efficiency, and clouds can still cast shadows without needing constant updates.