ekenryd Posted January 14, 2014 Share Posted January 14, 2014 (edited) Hi, I'm new to houdini and I wonder how you pin geometry when using packed objects? I've shattered some stuff and want them to remain in place, i.e not effected by gravity, until my colliders hit them. What is the most common way to do this with packed objects? My google fu seems inadequte when it comes to houdini. Thanks for your answers. Edited January 14, 2014 by ekenryd Quote Link to comment Share on other sites More sharing options...
teratera Posted January 14, 2014 Share Posted January 14, 2014 Hi, Have you watched this? https://vimeo.com/80840429 Quote Link to comment Share on other sites More sharing options...
ekenryd Posted January 14, 2014 Author Share Posted January 14, 2014 While very interesting, it felt quite high level sometimes (still at a very basic level) and it still didn't really solve my problem. I just want a simple pin constraint, which defies gravity and breaks depending on the force it gets. I will look more into it, thanks for the link anyhow. 1 Quote Link to comment Share on other sites More sharing options...
cwhite Posted January 15, 2014 Share Posted January 15, 2014 The 'Chains' example file for the Constraint Network DOP shows how to set up pin constraints for packed objects. An alternate approach would be to use the 'active' point attribute to make the object static until an impact occurs against the object. Quote Link to comment Share on other sites More sharing options...
ekenryd Posted January 15, 2014 Author Share Posted January 15, 2014 Yes, I solved it with the active option. I will check out "chains" later, thanks for the tip! Quote Link to comment Share on other sites More sharing options...
ekenryd Posted January 15, 2014 Author Share Posted January 15, 2014 (edited) Another question: does force affect constraints in different ways than a collision? and that chains-asset only crashes when I try to load it. Edited January 15, 2014 by ekenryd Quote Link to comment Share on other sites More sharing options...
cwhite Posted January 17, 2014 Share Posted January 17, 2014 Forces aren't any different - they cause the object to move (and violate the constraint), and the solver then does some work to attempt to enforce the constraint. The exception is glue, which only can be broken by collisions. I'd suggest submitting a bug report if an example file is crashing. Quote Link to comment Share on other sites More sharing options...
Mzigaib Posted February 1, 2014 Share Posted February 1, 2014 Since this thread is open I would like to ask help to understand the "Chains" file example in order for me to understand the pin contraint with packed RBD objects. In the end of the contraint network you end up with the double of the points, which seems to be one for the anchor and one for the goal position, correct me if I am wrong, but there is also one point with no piece attribute relating to it even though it acts as the top pin constraint, it´s really confusing can anyone give a little explanation about how the hard constraint DOP really work with those network constraints? Thanks! Quote Link to comment Share on other sites More sharing options...
Filipp Elizarov Posted February 2, 2014 Share Posted February 2, 2014 Firstly For HardConstraint - both points of your primitive(line) for constraint should have a name attribute (point) for instance piece50 for point0 and piece150 for point1 if they have proper names they will know which points from packed primitive they should constrain together.And secondly both points of your primitive(line) should be in the same position for example in the center of first piece from point0 or point1. Hope it will help you. Quote Link to comment Share on other sites More sharing options...
Mzigaib Posted February 2, 2014 Share Posted February 2, 2014 (edited) Thanks man! it helps but I still have some questions if you don´t mind. Let´s say I want to pin all the pieces from my broken torus to a certain point in the air, which point should be at the position in the air? point 0 or 1? I mean how I thell houdini that that I want to pin my torus pieces in that position in the air? I hope it makes sense for you. Thanks again! Edited February 2, 2014 by Mzigaib Quote Link to comment Share on other sites More sharing options...
Mzigaib Posted February 2, 2014 Share Posted February 2, 2014 I tried this but it didn´t work. pin_packed_objects_fail.hipnc Quote Link to comment Share on other sites More sharing options...
cwhite Posted February 3, 2014 Share Posted February 3, 2014 Thanks man! it helps but I still have some questions if you don´t mind. Let´s say I want to pin all the pieces from my broken torus to a certain point in the air, which point should be at the position in the air? point 0 or 1? I mean how I thell houdini that that I want to pin my torus pieces in that position in the air? I hope it makes sense for you. Thanks again! The pin constraint ensures that the positions of both anchors always match, so you would want both anchor points set to be at the position in the air. Also, if one of the anchors is not attached to an object, but is attached to a world space position, it needs to have an empty 'name' point attribute. pin_packed_objects_fail.hipnc Quote Link to comment Share on other sites More sharing options...
Mzigaib Posted February 3, 2014 Share Posted February 3, 2014 (edited) That explains a lot! Thanks man, that was really helpfull! Maybe this info should be more explicit in the manual Edited February 3, 2014 by Mzigaib Quote Link to comment Share on other sites More sharing options...
dlaga27 Posted February 4, 2014 Share Posted February 4, 2014 Along similar lines, does anyone know how to get packed prim rbds to be glue constrained to an animated deforming surface? For example, if you had a deforming surface bend, and as it bends, pieces that are glued to it would start to tear and pull apart the rest of the objects constrained to it. I'd rather get a glued response than a pin which has more degrees of freedom. When using the same example above with a glue constraint instead of pin, it seems to just stretch. Quote Link to comment Share on other sites More sharing options...
willow wafflebeard Posted February 7, 2016 Share Posted February 7, 2016 (edited) i was thinking of the same thing although glue constraint doesn't seem to respect world space anchors, we probably need to place bogus packed objects for it to attached to, and set it to never collide unto anything,hopefully in the future we get more opitons, glue has this nice ability to bunch objects together as one, unlike the hard/pin constraint which will stretch or jitter, seems to me that glue is much more worthy of the name hard constraint. Edited February 7, 2016 by willow wafflebeard 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.