Quote from: nixx on March 30, 2011, 09:08:24 AM
I 'm experimenting & practicing with snowy surfaces, and I 've bumped into a slight problem. I can't find a way to create a thick, smooth layer of snow over a rough, irregular terrain. Using the "Surface layer" approach gives convincing snow results, but the snow layer, no matter how thick, always inherits at least some of the underlying terrain's roughness - even with the smoothing effect on.
Think extremely rough, even spiky terrain, after a heavy snowfall. The roughness would be completely covered and the area would appear silky smooth.
The "smoothing" function uses the smoothed computed terrain from the compute terrain prior to the surface layer.
So if you have more than one compute terrains, it uses the last one (lowest) in the network.
Also, even if you have "smoothed normals" unchecked in the compute terrain, the "smoothing" function in the surface layer uses the smoothed terrain as input.
As far as I can tell you're aware of these ideas, so that's good.
The reason why your snow isn't covering the terrain can have two main reasons:
1) the patch size of your last compute terrain is too small. Imagine smoothing out 1m spiky features will still look spiky compared to 10m features smoothed. Simply put.
2) you don't use the right parameters for the displacement intersection mode. Unfortunately I don't fully understand what the 3 parameters of the intersect underlying feature do. We, alpha-testers, have asked Matt several times so far, but no answer yet.
Normally small values for intersection zone work fine.
The shift values represent the thickness of the layer.
So depending on the scale of the scene and the scale of the spikes you're trying to cover, you'll need to adjust the shift parameters accordingly. I believe the parameter is in metres.
It takes quite some trial and error without knowing exactly what these parameters do.
Cheers,
Martin