Rain of Alan Wake 2
Rain in Alan Wake 2 is omnipresent, symbolic and moody. I was tasked with taking care of the Rain question and went above and beyond to accomplish this task almost all alone, making Rain one of THE effects that I am proud of.
1. The Rain has research behind it - the droplets were made to be physically correct at first, later devolving due to many optimizations, but sticking to art direction of the project.
2. It features Remedy First GPU particle system, designed and coded in HLSL compute shaders entirely by me, showering the world with over 128000 particles. It is a barebones system but handles Rain very well - every droplet can collide with the ground and spawns a splash in that exact position. Sounds basic, but it is not a given in games!
3. Rain occlusion is handled by a Tiled World Height Buffer - a texture containing quite detailed height data of the world that drives rain's collision rendered in tiles, for performance's sake.
4. A huge heap of curves and Lua systems that drive Rain intensity over various portions of the game - from a small drizzle to heavy thick rain, with tools for level designers to invoke heavy rain or kill it off at will.
All of this was possible thanks to the Northlight engine team - as a special "Thank you" i have to credit Daniel Forsberg, as his tools and help enabled the majority of my work on rain!
Few additional curiosities:
- The rain slows down with lower framerate to perserve more or less the same length of a raindrop, treating framerate as "shutter speed" of a camera.
- The rain renders only in front of the camera, droplets that move out of camera bounds respawn instantly on the other side, making the most use out of 64000 droplet particles.
- Droplets do not collide with trees because... trees move too much.
Rain is almost omnipresent and builds constant ambiance around all kinds of areas
Rain is also almost constantly on in Dark Place, adding to the feeling of damp, dark city
I also multiplied the rain shaders onto other things, like leaking water sheets! Those particular ones were done by Pol Rius