Monday, February 20, 2012

Houdini Snow Tool WIP

Houdini's greatest selling point as a 3D app is its procedural workflow. I wanted to create a tool that could place snow geo on environments without having to model the snow. You could just build out your environment without snow and then use this tool to generate the snow on top of everything. I spent a morning with it and came up with a rough beginning. The basics are in there but it could be refined a bit:

You'll notice that which ever way the torus is rotated the snow stays on top. As is, the snow isn't shaded yet. I know that I could do all of the snow in displacement and I may yet play with that a little more as I work with it.


NateTheGreat said...

Great look you are getting here. How
did you get it to pile so nicely? Any chance I could look at your file?

Nate Shaw said...

Hi there, This is a rather old post so I'll have to dig around for the file. The basic idea is to create an attribute for the placement of the snow. Since snow usually piles up we can use the dot product of the N and 0,1,0 vector. Do that in a vopsop and pipe it into Cd to visualize it. Once you have that attribute you can make the snow in a variety of ways, with geometry or in the shader. In this example I believe I just scattered points based on that attribute and then copied metaballs or used the particle surfacer to create the snow geometry. Hope this helps and I'll look around for that file, if I find it, I will post it on here.