3 replies to this topic

[Scratch]

Hey odforce

Once again I need your help! How can I make a RBD-fracture-object stick to the ground so that only the broken pieces fly away, but the base of the object stays where it is
e.g. a building is hit by a projectile. I want that the fracture pieces break away, but the unaffected base of the building should stay where it is.

I managed to stick a test-cube to the ground using a pin constraint. I hit this cube with a sphere, and it works as I want. But when I turn on clustering (to cluster the fracture pieces like I want it (e.g. that the exterior stays in one piece). The constraint does not have an effect anymore. Why is that?!

I've attached a hip-file for you to take a look at and would be happy about some input how to solve that problem. My primary objective (why I am doing all this tests) is that I have to create a cliff or iceberg like structure, whith an overhanging part which should breaking off. (Like it happens with ice-bergs form time to time). The Ice-berg should stay where it is (not moving), but the fracture-pieces should slide off.

Any input would help! Thx alot in adavace!

Attached Files

•  fracture_test_01.hipnc   280.44K   57 downloads

[Rudinie]

Ok, that's pretty easy to see if you open your scene and use the technical desktop.
In the details view you will see that the box_object1 will cease to exist once the sphere impacts. It will be replaced by a bunch of box_object1_2_piece_n objects.
If you put in a asterix (*) in the constrained object it will work again: box_object* for example.


Why do you use dynamic fracturing? If you prefracture you will have all the control you need.

[bloomendale]

Rudinie, on 25 June 2012 - 06:18 AM, said:

Ok, that's pretty easy to see if you open your scene and use the technical desktop.
In the details view you will see that the box_object1 will cease to exist once the sphere impacts. It will be replaced by a bunch of box_object1_2_piece_n objects.
If you put in a asterix (*) in the constrained object it will work again: box_object* for example.


Why do you use dynamic fracturing? If you prefracture you will have all the control you need.

It doesn't work this way afaik. You can't use object mask in pin constraint. You can constraint each object to its pivot by using Apply relationships node, use something like argc(dopobjscreatedby("../fractureparms")) as number of rels and stamp pivot pos info of every object to pin constraint node. This way you constrain ALL frags. So you need to decide which pieces to constrain first.

Or you can simply change the active state of the objects -> use dopoption($DOPNET, $OBJID, "Position" "py") > some_height as activation for Active State DOP(don't forget to Set Always). This way every frag with pivot Y coord > some_height at $CT became passive.

Another way is to glue all frags to ground with some glue force.

Edited by bloomendale, 25 June 2012 - 09:59 AM.

[Scratch]

Thx for your tips folks! But that sounds very complicated to be honest.
Isn't there a easier way to create a cliff or ice-berg, and then let some part of it break off? I think this is something you come across pretty often, there has to be a simpler way?!

EDIT: Rudinie's approach seems to work. But still, if there is a easier way, I'm happy to give it a try!

Edited by Scratch, 25 June 2012 - 11:34 AM.