Hey all! I am working on a shot for a friend and this is the first time I am working with flip fluids. I would like to use some kind of density attribute to represent how many particles are close to each other. I would then use this attribute to control the occupancy of my shader. What would be the best way to do this? Would it be to use a VOP and use the neighbor count to get the number of surrounding points and use that to create a density attribute?

Here is the rough WIP of the shot: https://vimeo.com/48777494 [vimeo.com]

Thanks!
James S

The Neighbour Count VOP is to query how many points are connected to the current point.

What you want to do is use the Point Cloud Num Found VOP. Normally this VOP is used to create the maximum counter for a While Loop VOP but in your case it looks like this is all you need to find out.

Here's a link from yesterday that has just such a VOP Point Cloud network that simply returns the number of points nearest to the current point within a given radius as an attribute:
http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=26762&highlight=&sid=163854defcaee7b9ad32350f209d8ac9 [sidefx.com]

Here's a nice web page from Mr. Sawtell that shows a couple iconic Point Cloud based VOP networks for learning purposes:
http://www.msawtell.com/research/point_clouds/point_clouds.shtml [msawtell.com]

And here's my simplified version that explicitly returns the number of neighbouring points within a given search radius and a maximum bound to the number of points in the attribute “numpoints”.

Good deal Thanks Jeff! I will check out this as soon as I get home!