I just realized myself how much SpaceEngine could benefit from seasonal planet textures. I was contemplating making another new Saturn texture for southern winter (I had already done one for equinox) when I thought about how inconvenient it is to switch such textures every season (not as much for Saturn of course ). Then I thought about a way that this might be implemented. It would be crude, but it seemed like it might be fairly easy to implement.
Similar to the way corona textures cycle now, with one smoothly fading into the next, something similar could be done with planet textures. Here's the idea I had in mind for how it could be called in the catalog files.
There would be a parameter called perhaps SeasonalDiffMap, with a value of true or false (if not specified, assumed to be false). Similar parameters could exist for CloudMap and BumpMap. Then there could be another parameter called SeasonalMapNumber which would specify how many textures would be cycled through (may not be necessary, I'm not sure), and would have an integer value greater than 1. Then there would be parameters to specify the textures to be used in the seasons, like DiffMap0, DiffMap1, DiffMap2 and so on. The same could be done for Bump and Cloud maps. The engine would cycle these textures at regular intervals until it came to the last map, at which point it would cycle back to the beginning.
There could also be parameters to specify the start and end dates and to specify whether the cycle should repeat (specifying a long time scale and non-repeating progression could be used to simulate terraforming in addons). Before the start date, the planet would use the earliest set of maps, and after the end date, it would use the last set. For cycling textures, a SeasonalEpoch parameter can be specified to set the date at which the cycle starts (it would cycle both before and after this date, however at this date the cycle would be exactly at its starting point). The times would be specified by the Julian date.
So a sample code for a terraforming Mars could look like this.
And a code for Saturn might look like this:
If this process could be translated to procedural worlds, then it could be used to change sunspot patterns on stars as well.
I was about to create a new thread with a similar topic when I found this one. SpaceEngineer, is it okay if I rename it to "Seasonal Planet Textures" and move it to Feedback and Suggestions? It seems like it would be more appropriate there.