Wall Fracture Set Up Help

[talen.herzig]

Hi all,

 

I'm playing with dynamics of fracturing objects and I'm wondering how to go about setting something up properly. What I want is a wall that fractures upon impact, but holds together prior to that, and only fractures at impact points where there is enough force to do so, with the basic effect of a wall that, when hit with a sphere object, only fractures at the geometry closest to the impact point. Similar to say, concrete being hit with a heavy object. Using the Voronoi Fracture nodes in the geometry object, I've created the wall fine, but when I turn it into a rigid body object it immediately starts falling apart. I've tried glue constraints, but they don't seem to hold it together as well as I would like and as soon as the object it hit, it still falls apart much more than I'd like, and often pushes the entire wall back until the shatters against the ground plane. I've also tried using pin constraints at the bottom and sides of the wall, but it didn't help hold the wall still.

 

Firstly, am I using the glue constraint wrong? Should I be able to get the desired effect using the glue constraint, and if so, could anyone point me to a tutorial that would help me understand it's use and limitations better?

As a potential solution, I was considering setting all the geometry to be passive using an Active Value node except where the impact force is greater than *value*, but I am not quite sure how to go about this, or how to set up the necessary attributes. Any help would be appreciated.

[Rainroom]

You need to pin the corners of the wall to the ground, so that it holds still when hit by something. Look for pin constraint examples in the dopnet.

[talen.herzig]

I think I may have been misunderstanding how the pin and glue constraints worked, as well as exactly how high you have to set the glue constraint to get the correct result. I may have to play with it a little more. What I did was create a pin constraint, remove the goal object, and change the constrained object to "piece*" instead, with the wildcard, then create a glue constraint on the object with a much, much higher strength. It gave me a lot closer to what I wanted, and pinned all the pieces a little bit better. I get the feeling that to get any better will require being a little more specific in what I feed the Voronoi Fracture nodes in the geometry object. Does anyone else have any advice on what might be a good way to use these constraints, or is it kind of arbitrary trial and error to get results?

[NSugleris]

You could always extract the packed points, and use an active value to trigger the destruction based on the trigger objects proximity or you could always lock the ground chunks to being passive / inactive.  

 

  When it comes to keeping the base on the ground there's really just so many ways to do it. 

 

I'd check out here too : http://forums.odforce.net/topic/19114-set-activevalue-in-a-packed-object/   Good post by Tomas with a hip file as well.

 

 Here's an example of making the points near the floor inactive:  http://forums.odforce.net/topic/19529-how-to-fix-a-fractured-rbd-object-to-the-ground/

 

     Cheers

Edited September 16, 2015 by NSugleris

[biswajitfx]

learning from "Applied-houdini" this mi ght help 

RBD_applied_01.hip