CloudWright

September 19, 2007 – 9:59 pm by Roderick Kennedy

I’ve long had an interest in rendering realistic clouds for games. The usual approach – taking photos of the sky and stitching them together into a dome or cubemap – produces convincing skies but has a number of disadvantages. If you want to use high dynamic range, you either need to take a full HDR picture of your sky, or to fake it convincingly. It’s static, lacking the infinite variety of real skies.

CloudWright is a program written with Simul that generates skies. It outputs cubemaps that you can use in-game. It can cover pretty much any kind of “fluffy” cloud with full physics-based lighting – cumulus, stratus, cumulonimbus. The lighting is based on date, latitude and time-of-day information.

Here is some early preview output from CloudWright:

CW2.jpgCW8.jpgCW5.jpgCW4.jpgCW7.jpg

 

The Simul framework helped a lot with this – I could easily build objects with saveable properties, so I didn’t have to worry about file formats – the framework does all the work. In this case, CloudWright just remembers what your data was when you last ran it. Later on I’ll put in a save/load setup and more bells and whistles.