christianl013 Posted January 8, 2018 Share Posted January 8, 2018 Hi Guys, I have a system of Pops where particles are following several splines with a PopCurve Force node. I got everything working the way I want except for one small detail that I have not been able to figure out. The detail is how do I align the particles so that they face the direction of the spline? I don't want them to bank along the spline per se but just have an axis aligned to the spline almost like dominos or people marching in a single line along the path of the spline. It has to feel very organic which is why I am using POPs with forces and things like that as opposed to doing it in SOPs. I thought maybe a POP LookAt would work but I am not sure how to get the curve alignment data to POPs. I am sure this has been done twelve ways from Sunday but I am pretty new to Houdini and haven't able to figure it out fully as of yet. Anything advice on this would be awesome. Thanks! Cheers, Christian Quote Link to comment Share on other sites More sharing options...
mestela Posted January 8, 2018 Share Posted January 8, 2018 It should do that by default; if you have @v (and not @N or @orient), when you use a cop sop to copy geo to the particles, they should point their z axis along v. http://www.sidefx.com/docs/houdini/copy/instanceattrs.html Examples and gifs and stuff here: Quote Link to comment Share on other sites More sharing options...
mestela Posted January 8, 2018 Share Posted January 8, 2018 Also, a japanese houdini user wrote a great tutorial about a better pop curve force setup; google translate does a pretty good job, but you can also just grab the hips linked at the end of the article: https://qiita.com/taikomatsu/items/71d475541eb540705552 1 Quote Link to comment Share on other sites More sharing options...
christianl013 Posted January 8, 2018 Author Share Posted January 8, 2018 Thanks alot, your answers were very helpful. One thing all these example files have is one spline per scene and this is piped into the pop/dop network with the first or second context inputs. But what if I have alot of splines that I need particles to follow? Can I call pcopen on a wrangle and just point it to the spline directly or how does one go about this type of setup with multiple splines in the system. Thanks again. Cheers, Christian Quote Link to comment Share on other sites More sharing options...
christianl013 Posted January 8, 2018 Author Share Posted January 8, 2018 looks like a just answered my own question on using mulitple curves. But what if we want the particles to orbit around the axis of the spline? How does one acheive that? Cheers, Christian Quote Link to comment Share on other sites More sharing options...
mestela Posted January 8, 2018 Share Posted January 8, 2018 Something like this? I'm dumb and would need to see the geo of the spiral curve, but I'm sure the logic within here could be used to generate a spiralling force directly in pops. coil.hip Quote Link to comment Share on other sites More sharing options...
bergerac14 Posted May 20, 2019 Share Posted May 20, 2019 Hey @christianl013, I've got a similar problem where i need to use multiple curves to contol a pop sim with curve force; would you mind sharing with me how you achieved it with pcopen? Thanks in advance! Cheers, C Quote Link to comment Share on other sites More sharing options...
christianl013 Posted May 20, 2019 Author Share Posted May 20, 2019 Yeah, in summary, you have to calculate v by importing the tangent normal of the curve and pcopen allows you to import the normals from the curve so that you can use it for velocity and in turn apply that to your POPs. You can also just try using the pops curve force node, it works with multiple splines as well. I hope that's helpful, the files linked in this thread were helpful for me as well and hopefully could be of some use to you too. Cheers, Christian Quote Link to comment Share on other sites More sharing options...
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