Weather forecast for the coming game: cloudy with lots of rain!

We wanted to add weather particles to our games. And we wanted A LOT! Our existing particle engine was not capable of simulating millions of particles in real time and we could only add them to a limited area. To solve this problem we added boxed movement and batch rendering for particles. This means that we simulate between 50 to 200 particles in a limited area, say 3x3x3 meters and render this box of particles multiple times in an grid of 3x3x3, having a larger weather cube that follows the camera seamlessly.

We also stretch particles in the direction they move and also by camera movement so you get a star field like effect when you are moving pretty fast trough the rain or snow. Here are two movies to demonstrate the effect.

We can already color the sky and change the lighting, and by adding weather effects we hope to create a more dynamic world with real time changing weather.