Hi guys.

Lip spray from cresting waves! I've been playing around a little, and I would like to emit spray from the sharpest crest's of a deformed surface.
I could go the attributetransfer way with colour, however that is very slow on a highly displaced mesh.

What I'm looking for is; a smarter way of selecting specific points based on perhaps the angles between surrounding points (vop sop).

I had thought about using a measure sop to measure curvature and group those points, but I did'nt get the wanted result (probably me doing something wrong).

Cheers.

Hey ragupasta, what about using the edge tab under group SOP? they have an edge angle mode. It works on primitives, but you can then convert it to points

Thats a good idea, however I have found it a bit non-intuative at times. Sometimes it works, and sometimes not.
I was really looking for vopsop action to be honest, as im kind of a sop-basher, and I really should get into the chewy math side of things.

I was thinking of something along the lines of taking the normal of each point position, and running that through a neighbour sop with some funky math trick to define an angle between them, then using that to group some points for particle emission.

Cheers for the suggestion though, the edge part on a groupsop was something I never think about!

hahaha! never heard of sop bashing that is priceless

Yeah I think what you are thinking of makes sense (heck it would also give you a nice simple way to group sharp points…. currently with the group SOP you have to invert selection, convert to points, then invert again to get the sharp points)

The funky math should be simple I think. You can calculate the difference of the point normals and if it reaches a certain threshold, add the point to a group.

oops , didnt read your first post carefully .

( measureSop > curvature )