These are true, GPU ray-marched clouds based on underlying 3D volume textures, which we think is a first in the world of X-Plane. They also integrate with our Real Weather Connector product, meaning localized cloud formations can be realistically flown into and out of – you don’t just have uniform weather surrounding the plane at all times.
Some screenshots (click for full size):
Getting 3D textures to render efficiently across a large area is tricky to put it mildly, but we think our approach brings some novel ways of boosting performance without compromising too much quality. We also did a bunch of work to tune SilverLining’s volumetric clouds to blend nicely with X-Plane’s lighting and deferred HDR rendering engine, and to integrate our bounding-volume-based ray marching with X-Plane’s terrain. We accomplished the latter by extending SilverLining’s stratocumulus fragment shader to read a copy of X-Plane’s depth buffer to determine the depth of the terrain at each fragment, and compare that to the depth of each ray march in order to properly terminate the ray when it hits something in the scene. It’s not just terrain, but also objects in the scene – so at long last, you can see your own plane properly fogged as you fly through a cloud.
We’re pretty excited about this release, and it’s also driven some exciting improvements in the SilverLining SDK as well. If you fly X-Plane, check it out!