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catchyid

Breaking Glue Constraints - Bullet?

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Hi,

If you have glue constraints network (using Bullet), it's possible to break them using a colliding object (e.g. a moving sphere that is flagged as animated static). However, is it possible to break them using abstract forces (e.g. using field or fluid forces, or even uniform force)? I've tried many types of forces, but regardless of their strength they don't break constraints. I've noted that packed pieces don't have "F" attribute, neither the Glue primitives (i.e. impacts = 0)? I only get impacts if I use collision geo, and "F" I apply POP forces...

Another related question: in addition to breaking constraints by colliding object, sop solver, and geometry wrangler, Is there another way to break glue constraints?

 

Thanks

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Posted (edited)

Just a quick update, I can actually break constraints using targetv and pop force...it's just requires "big" values and constraints should be "somehow" easy to break (e.g. if I break some constraints, then the rest won't be able to withstand the force)...I guess, using a collision object is the safest and easiest way to break constraints...

 

Seems like the only way to break constraints is either manually by placing them in broken group or a colliding object...

Edited by catchyid

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Yet another update if someone is reading: it's possible to break constraints using forces, basically use v@force at each packed primitive and if it's strong enough it will break the constraint. Note, initially I've used force dop nodes and they did not break the constraints, but when I replaced them with v@force constraints got broken nicely...

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Does that work for glue constraints as well?  I thought glue constraints could only be broken by "impact" which in turn could only be imparted by a collision constraint (aka something hitting it).

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sorry! that update was outdated :) in summary, after looooots of testing, two ways only to break glue constraints: (1) manually, i.e. add it to broken group (i remember it's actually an attribute that you need to set to 1, but I don't remember the exact attribute name), or (2) via impact, i.e. something has to hit the object containing the glue constraint (and it has to be fast/heavy enough to break the constraint). So, using forcing alone will NOT break any constraint...

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you can get @force from anchor pieces per constraint and compute the difference in any way you seem fit to get the strain acting on the constraint and then break it if it's higher than threshold

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Kind of a pedantic question related to glue -- is "impact" a force or an impulse?  Can't seem to find the units...  I assume it is the sum of magnitude of linear/angular forces needed to counteract collision forces.

(I'm trying to use anim suggestion and break glue constraints based on nearby hard constraints torque)

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