"Prevailing Winds" should affect pollution spread

[behrooz]

I was really impressed by the water pollution visualization in FFF#358. However, when zoomed way out, it becomes really obvious that with a lot of water the pollution distribution resembles a perfect circle because there is nothing on water to affect how the cloud spreads. On land it isn't as obvious because forests and spawners absorb more in some areas and make the border of the pollution cloud less regular, but it's still obvious that it's mostly a steady state system-- pollution in any one area is roughly constant unless something major changes.

We can contrast this to real environments, where there is generally a prevailing wind based on the local climate-- pollution spreads generally more in the direction that is more often downwind.

As an example of how this works, and how cool it could be, look at this real-time visualization of air quality and winds from satellite data.

The best part is that the game engine is already simulating random spread of pollution across chunks, so in order to simulate the effects of a prevailing wind all that needs to be done is apply a weighted transform that makes it more likely for pollution to move along a defined vector. Even something small like "northward is 80% of normal pollution change, southward is 120%" would end up having a big effect, and should be a relatively cheap addition when compared to the existing computation budget used on non-weighted pollution movement.

As long as the average 'prevailing wind' direction does not change very often relative to the speed that pollution propagates, this would 'smudge' the pollution out in various directions.

The 'prevailing wind' weighting factor could change slowly over time, making a less regular cloud, and sometimes changing the shape of the pollution cloud dramatically. This would be cool because it would be reflected in the forest wasting patterns, and could probably result in more alien attacks from a different direction after the wind has changed.

For bonus points, where possible it would be really cool to have the current prevailing wind also affect the direction/speed of smoke sprites!

[ssilk]

Perfect idea for a mod...