dpap Posted March 28, 2013 Share Posted March 28, 2013 Hi! I am trying to escape from a painfull, long time relationship with Maya so if you can, please help out the Houdini newbe ! I started with the Waterfall tutorials from Go Procedural. I cached my fluid simulation and imported through a file node. How can I delete the particles that live outside a cube for example? The reason is that i dont want to mesh all the particle while I am tunning the fluid surfacing parameters. I think Realflow has something equivalent. Thanks in advance! Quote Link to comment Share on other sites More sharing options...
Annon Posted March 28, 2013 Share Posted March 28, 2013 Stick down a groupSOP, enable the bounding option (second tab), make sure you disable number... Move the bounding box as you like (or use the second input etc) to get your bound. Name your group. Put a delete node underneath it. Enter the group name (or drop down list). Set operation to Delete Non-Selected. Entity to points. Done. 2 Quote Link to comment Share on other sites More sharing options...
dobin Posted March 28, 2013 Share Posted March 28, 2013 also if you're using particle fluid surface SOP you could use Bounding Box tab to specify where this node generates a surface 1 Quote Link to comment Share on other sites More sharing options...
dpap Posted March 28, 2013 Author Share Posted March 28, 2013 Thank you guys very much!!! Both ways did the trick! Using a Group has the advandage of being able to use a polygon primitive as a bounding object and manipulating the points into custom shapes! Is it possible to use an already existing geometry from my scene (that lives at the object level,like an edited polygon .obj) instead of pluging in a new primitive ( from the tab menu) to the second input of the Group node? I mean how do you bring/reference other SOPs into this network? Copy paste didn't work I am afraid... Quote Link to comment Share on other sites More sharing options...
Annon Posted March 28, 2013 Share Posted March 28, 2013 So you can do an objectMergeSOP to bring in that geo you want from another /obj node. Usually you should put a null down at the end of your network (so in this instance whatever object you want to pull in) and call it OUT. When you select nodes in object merge you'll see that nodes starting with a capital will jump to the top of the list. I'll usually have one geometry node at obj level with my character in. Maybe with various OUTS (OUT_SKIN, OUT_HEAD, OUT_COLLISION etc) and then if I'm doing a smoke sim That'll be in another geometry network and I'll object merge into that. Another for any particles, another for RBDs etc. You can have them all in one, but it's easier to maintain in a handful of /obj level nodes and objectMerge the bits you want in. 1 Quote Link to comment Share on other sites More sharing options...
Skybar Posted March 28, 2013 Share Posted March 28, 2013 I read somewhere that the Blast node is faster than the Delete node, but I don't really know the difference so I'm just popping the question in here: When do you want to use Blast instead of Delete, and vice versa? Is there any advantage to use on over the other? Quote Link to comment Share on other sites More sharing options...
Annon Posted March 28, 2013 Share Posted March 28, 2013 Funny you should ask that, I was curious myself this morning. The help just says that delete is more procedural and blast is mainly for when using the shelves, selecting points and hitting the blast button etc. Which I hate, so don't use. I've worked on some pretty big geo with delete nodes and using the performanceMonitor it's never caught my eye as hogging anything up compared to any other node, so I wouldn't worry about it. Quote Link to comment Share on other sites More sharing options...
kni8_2k Posted March 29, 2013 Share Posted March 29, 2013 I think the Delete nodes Slowness has dwindled with the onset of 12.x versions. I use to use copy instead of delete for primitives as it was much faster. now its pretty much the same. Quote Link to comment Share on other sites More sharing options...
edward Posted March 29, 2013 Share Posted March 29, 2013 FWIW, the Delete SOP also has bounding box/sphere options as well. 1 Quote Link to comment Share on other sites More sharing options...
dpap Posted March 29, 2013 Author Share Posted March 29, 2013 Thanks for all the responces! It was crusial to isolate only a portion of the whole particle cache, since its quite hard to manage the.... 31million particles/per frame! I know it's an overkil but I just wanted to test the capabilities of the flip solver/houdini and I have to say am amazed! Minimal disk and ram footprint plus speed! It's crazy! I have to say though that I haven't managed yet to fully take advantage of the ridiculously high amount of particles to get an accordingly detailed mesh...I'll keep trying! Quote Link to comment Share on other sites More sharing options...
patrickkrebs Posted September 27, 2018 Share Posted September 27, 2018 Was just dealing with this issue in Houdini 14.5 and some thigns have changed. To help out if someone finds their way to this thread... I wanted to take a .sim cache from a flip solver and isolate the splash from the rest of the body of water. This can be done with the delete node as the first thread suggests. Houdini has kind of consolidated things since 2013. Operation: Delete non-selected Entity: Points Second Tab Bounding Volume: Enable Bounding type This should work. Good luck future adventurers! Quote Link to comment Share on other sites More sharing options...
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