Pioneer Clouds

Posted by | Posted in environment, Game Development, Pioneer | Posted on 03-06-2016

Some time ago I tried slapping a texture of the Earths clouds onto a sphere around Pioneers planets. It didn’t look awful but it was a static texture meant for just the Earth itself and having a selection of high-resolution textures to pick from would look very repetitive uncomfortably quickly.

As usual in a thread like that I immediately got asked why it wasn’t better, why aren’t I doing like X,Y or Z, etc but the idea is still bubbling away in my head. The thread itself was really just to gather resources and ideas rather than to track anything.

Now I have a small gallery of test images based on some noise based shaders which update over time but look rubbish.

See, from the ground:

From the ground

From orbit:

From Orbit

To get better looking clouds, ones that look like they’re generated by the planets surface and properties, you need to analyse that planets geography and the energy inputs/sinks.

There are a couple of interesting pages like the Stainless and Dungeon League sites who really dig into and iterate through ideas to produce some very interesting results.

Heat & Friction

Heat & Friction

2D normalised wind direction

2D normalised wind direction

I fairly sure that I can combine them already to get some interesting results but I hope that more than using them raw like this I can do some more processing to generate evaporation, rainfall (precipitation), rain-shadow style maps that will look even more compelling.

Right now I am basing the number of “bands” of weather on the Earth’s global atmospheric circulation which will not hold true for other worlds, so having some way of determining the number of “cells” to divide a planets circulation into will be necessary. Take Jupiter as an example, it has numerous “cells” which all have different gases being mixed into them giving it that distinctive layered look. Depending on the planets size, rotational velocity, atmospheric density, viscosity, heat absorbtion, angle of inclination to the nearest star(s), etc there could be anything from 1 to 100’s of cells dividing up the atmophere.

That would be something amazing to see, different on each and every world with corresponding weather systems and biomes.

That still won’t be the end however as all of this so far is excruciatingly slow to¬†generate, requiring as it does a decent level of heightmap detail.

Generating those heightmaps is the most expensive single process in Pioneer, which is why the development of the multi-threaded processing made such a big difference.

Some simplifications, optimisation and cleverness will be required before this can ever make it into the game proper.

PS: IN parting I should also add that working on this came about because I needed to generate from of this data for the new JSON driven terrain generation system and because of the XFrontier forum thread which just looked too damned good to pass up.