Glue Network Issue

[Skar]

Hey Guys,

 

I´m quite new to odforce and Houdini and a friend of mine recommended you very strongly. My Issue concerns glue networks with bullet fracture sims.

There is a ground (terrain) object and set of "fracture objects" on the ground. I want to delete the bonds between the fracture pieces, but NOT the connection between ground and adjacent fracture pieces between the ground. Is this possible with one glue network or do I need two? And how? I need a strong glue between the ground and the adjacent fracture pieces. 

Help would be really appreciated. I really like Houdini, but it takes time to get the overall picture concerning the mechanics.... I guess.

 

Best Wishes,

 

Luke

Break_06.hip

[DennisSchmidt]

The simplest way would be to set the chunks close to the ground to static. Going with constraints i would recommend creating seperate constraints. That way you got more control. A nice way i find to create constraints between touching objects is by scattering a large amount of points on both surfaces, create a seperate name for the two objects and merge them together. Then do the standard connect adjacent pieces sop. Now you should only see points in the touching area. Lastly transfer the old name attribute back on to the created constraintpoints. Give them a different constraint name and you can use them with the same constraint network.

Attached you can check out a simple example file to demonstrate what i mean.

 

Hope that helps and feel free to ask any further questions.

Dennis

constrainGround_v01.hipnc

Edited May 20, 2016 by DennisSchmidt

[Skar]

Hey Dennis,

 

vielen Dank! Detailed answer and samplefile, you are my hero! Gonna be back home tomorrow, can´t wait to adapt the changes to my project

[Skar]

On 20.5.2016 at 9:15 PM, DennisSchmidt said:

The simplest way would be to set the chunks close to the ground to static. Going with constraints i would recommend creating seperate constraints. That way you got more control. A nice way i find to create constraints between touching objects is by scattering a large amount of points on both surfaces, create a seperate name for the two objects and merge them together. Then do the standard connect adjacent pieces sop. Now you should only see points in the touching area. Lastly transfer the old name attribute back on to the created constraintpoints. Give them a different constraint name and you can use them with the same constraint network.

Attached you can check out a simple example file to demonstrate what i mean.

 

Hope that helps and feel free to ask any further questions.

Dennis

constrainGround_v01.hipnc

Hey Dennis,

sry, but I don´t really understand why I have to transfer the old name attribute back and even if I do so, why my sim is jittering. Added my adapted file. Maybe you could take a look if you have a moment.

 

EDIT: Btw, how do you set those specific "ground chunks" to static. Sry again, I´m quite new to bullet.

Break_06.hip

Edited May 24, 2016 by Skar

[DennisSchmidt]

I will check out your file later. You have to add back the old name since that is how the fractured chunks and the constraints are connected (a constraint point with lets say the name "chunk_32" refers to that specific chunk). Creating only two names (one for the object and one for the floor) is just for the connect adjacent pieces SOP so it doesn't create constraints for the object itself. Hope that makes some sense(?).

By creating a "active" integer attribute before going into DOPs you can set the status. Example: group the bottom half of the objects and add a create attribute SOP which only affects the points in the group. Set the default to 1(=active) and the value for the ones in the group to 0(or the other way around).

[DennisSchmidt]

First off you should create a unique name for your ground. Since it is called the same as your first fractured chunk(piece0). If you check your constraintnetwork node and look at the warnings it says that it can't find the floor. Thats because the terrain doesn't bring in the name. What i did was pack the ground and import that to DOPs via passive packed object. Don't forget to change the collision type to concave so you get accurate collisions for your ground. Now your constraintnetwork can find the ground. That should do it.

 

Hope it helps.

Dennis

[Skar]

Thanks a lot. It works now and even better, I´m understanding why