r-a-n-d-o-m Posted November 27, 2017 Share Posted November 27, 2017 Hi, This Hard Constraint (type: position and rotation) works perfectly fine in Houdini 13, but not in Houdini 16. The rotation falls apart and I have tried anything to get this to work, but without luck. It's a simple setup: a constraint between two boxes. https://www.dropbox.com/s/egytkvu5lg2q1mb/QA_HardConstraint_Rotation_Breaks.hipnc?dl=0 Quote Link to comment Share on other sites More sharing options...
mestela Posted November 27, 2017 Share Posted November 27, 2017 check your world constraints are an empty string, anything else will be ignored. eg @constraint_name=""; // good @constraint_name="world"; // bad Quote Link to comment Share on other sites More sharing options...
r-a-n-d-o-m Posted November 27, 2017 Author Share Posted November 27, 2017 (edited) hmm... I don't know where to apply this. The 2 boxes should be constrained to one another, do I need world constraints for that? Edited November 27, 2017 by r-a-n-d-o-m Quote Link to comment Share on other sites More sharing options...
mestela Posted November 27, 2017 Share Posted November 27, 2017 I don't have h13 installed, can you upload a gif of what its meant to do? The setup is behaving as expected as far as I can see; the first constraint locks only position, so the system pivots around that point when hit, the second constraint locks only rotation, so the second box is free to fall; there's no position constraint to hold it in place. Quote Link to comment Share on other sites More sharing options...
r-a-n-d-o-m Posted November 27, 2017 Author Share Posted November 27, 2017 The 2 boxes used to stick together with a rotation constraint only and the second box didn't fall down. Quote Link to comment Share on other sites More sharing options...
mestela Posted November 27, 2017 Share Posted November 27, 2017 Are either of these what you're after? I swapped the middle constraint to a cone twist, with the max out rotation at 180 so it can spin around the long axis. If I move the position constraint to the center its all stable, if I move it to the side it gets a bits wild, so I add some drag to calm the system down. QA_HardConstraint_Rotation_Breaks_me.hipnc Quote Link to comment Share on other sites More sharing options...
r-a-n-d-o-m Posted November 27, 2017 Author Share Posted November 27, 2017 (edited) Yes! It's the second one I was after. So, in conclusion: Box 1 has a pin constraint (constraint type "position" only) Between Box 1 and 2: Instead of using a Pin constraint with constraint type "rotation" (H13), we now (H16) have to use a ConeTwist Constraint (constraint type "all") to get the same effect. Thank you Matt!! (and keep up the good work you are doing on Tokeru.com!) Edited November 27, 2017 by r-a-n-d-o-m Quote Link to comment Share on other sites More sharing options...
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