Justin K Posted April 25, 2018 Share Posted April 25, 2018 (edited) Hello, Getting really frustrated trying to implement a seemingly simple concept. Im trying to build a simplified umbrella rig. There are only three parts- stem-- stretcher- rib- and - tube-- see picks. In my attached file, on a sop level, I cant find a mathematical way to keep "the stretcher" line objects to stay the same length, and have the anchor point on the tube move up and down the tube as the umbrella opens and closes. (in the pics Ive attached you can see the issue). Originally I thought that I could tie the perimeter attribute of the line to the carve position on object--basically retaining the perimeter --but I couldn't devise an expression relationship that works. I actually went and tried to do this on an object level using rigging tools and got even more frustrated- moreso because Ive never used the rigging tools in Houdini----. Bit frustrated here-- this seems like it really should be trivial. If anybody has a way to do this on a sop level Id appreciate the insight. And if anyone could show me an example of how to get it to work with a simple IK rig you'd be my hero. Thanks all. umbrella_rig.hipnc Edited April 26, 2018 by JKeil Quote Link to comment Share on other sites More sharing options...
Noobini Posted April 26, 2018 Share Posted April 26, 2018 here's a simple proof of concept...(not exhaustively tested for integrity tho...ie...if you make the stretcher length too short....it will try and try and try to reach the main shaft...but of course will never reach) vu_brolly.hipnc Quote Link to comment Share on other sites More sharing options...
Noobini Posted April 26, 2018 Share Posted April 26, 2018 added Max Angle control vu_brolly.hipnc 1 1 Quote Link to comment Share on other sites More sharing options...
Justin K Posted April 26, 2018 Author Share Posted April 26, 2018 (edited) Thanks Noobini, Implementing your workflow now. I did a bit of a break down of the math that you did for my own sake--felt like it wouldnt hurt to put it here for anyone else. EDIT: opposite side is not the distance between pt3 and the origin, it is simply pt3s x value--its distance in the x axis only Edited April 26, 2018 by JKeil 1 Quote Link to comment Share on other sites More sharing options...
Noobini Posted April 26, 2018 Share Posted April 26, 2018 yes that's how I worked it out...ie. draw diagrams...still using the old pen and paper system. 1 Quote Link to comment Share on other sites More sharing options...
McNistor Posted April 27, 2018 Share Posted April 27, 2018 Cool rig! Quote Link to comment Share on other sites More sharing options...
yglemarec Posted April 27, 2018 Share Posted April 27, 2018 (edited) Hello, your umbrella with ik bones umbrella_rig-ok++.hipnc Edited April 27, 2018 by yglemarec 2 1 Quote Link to comment Share on other sites More sharing options...
Justin K Posted April 28, 2018 Author Share Posted April 28, 2018 Thanks Yohann! Quote Link to comment Share on other sites More sharing options...
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