blur959 Posted April 12, 2011 Share Posted April 12, 2011 Hi all, I am trying to group a bunch of specific points to emit particles from. My first idea was grouping it according to normals, but I do not know how to only group the bunch of points with similar normal directions together and not group the rest of the points. I also thought of grouping them by just dragging over the points and making a group out of it, but it isn't very procedural. I also tried grouping the points according to a boundingbox but as my geometry is moving over time, the boundingbox couldn't maintain the grouping of the points.Can anyone give me some ideas on how should I approach this problem? Thanks a lot. pointgrouping.rar Quote Link to comment Share on other sites More sharing options...
graham Posted April 12, 2011 Share Posted April 12, 2011 (edited) If you want to group based on normals then in VOPs you could take a vector that you want to compare against and take the scalar (dot) product of that vector and each normal vector. You can then take the inverse cosine of the value, convert it to degrees and have an option defining the permitted angle difference/tolerance and then add it to your group if it falls within the range. Edited April 12, 2011 by graham Quote Link to comment Share on other sites More sharing options...
Macha Posted April 12, 2011 Share Posted April 12, 2011 What Graham says is correct, but there is also a vector based grouping option in the groups sop. Perhaps that will be sufficient. I didn't really look through your file (bulky) so I made my own (bulky) version to illustrate the technique. angle.hip Quote Link to comment Share on other sites More sharing options...
graham Posted April 12, 2011 Share Posted April 12, 2011 I always forget about that option. It's the exact same thing as I outlined above, but done automatically under the hood. Quote Link to comment Share on other sites More sharing options...
blur959 Posted April 13, 2011 Author Share Posted April 13, 2011 Many thanks to both graham and Macha for the help provided. Macha - Woah, your file looks so cool but it's kind of complex though.Still trying to figure out. But thanks though. Graham - Yeah, got it. Many thanks. Quote Link to comment Share on other sites More sharing options...
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