RBDs colliding with and deforming other RBDs

[august]

Hello,

I'm trying to create an effect of a gate being smashed down. I've rigged up some simple boxes as rbd objects with some pin constraints to keep the metal cross bars attached to the wooden vertical planks.

Ideally, the metal crossbars should bend and twist some from the force of the impact. Cloth objects give the bending I want, but cloth doesn't have the nice rbd pin constraint ability, so everything just tends to fall apart. For example, the crossbar should be nailed into each post. But when the cloth bar gets impacted it dents and just peels away from the posts that aren't moving yet. The cloth simulator seems a little too crash prone for me anyway.

Is there a way to use a sop solver or something to deform the crossbars slightly as they get impacted while maintaining proper collisions with the vertical planks?

Thanks for any ideas.

I've attached a simple scene with the rbd pin setup I described above.

--August

pin_test.hip

[sam.h]

Hello,

I'm trying to create an effect of a gate being smashed down. I've rigged up some simple boxes as rbd objects with some pin constraints to keep the metal cross bars attached to the wooden vertical planks.

Ideally, the metal crossbars should bend and twist some from the force of the impact. Cloth objects give the bending I want, but cloth doesn't have the nice rbd pin constraint ability, so everything just tends to fall apart. For example, the crossbar should be nailed into each post. But when the cloth bar gets impacted it dents and just peels away from the posts that aren't moving yet. The cloth simulator seems a little too crash prone for me anyway.

Is there a way to use a sop solver or something to deform the crossbars slightly as they get impacted while maintaining proper collisions with the vertical planks?

Thanks for any ideas.

I've attached a simple scene with the rbd pin setup I described above.

--August

I did a test doing this a while back, I think it has been archived :/ if I get some time I will put an example together but all I did was use a SOP solver to deform the RBDs - impact data should be in the SOP solver already (if it isn't just look for the expressions to use in the docs). Each impact was a point with an 'impulse' attribute ( I think ). I just attribute transferred that onto the mesh and deformed along that vector. The RBD SDF will update automatically for you when the mesh changes.

[august]

I did a test doing this a while back, I think it has been archived :/ if I get some time I will put an example together but all I did was use a SOP solver to deform the RBDs - impact data should be in the SOP solver already (if it isn't just look for the expressions to use in the docs). Each impact was a point with an 'impulse' attribute ( I think ). I just attribute transferred that onto the mesh and deformed along that vector. The RBD SDF will update automatically for you when the mesh changes.

Thanks. I found a similar example after some digging around.

[dangerweenie]

Thanks. I found a similar example after some digging around.

Hey, just found this.

Do you think this technique would be appropriate to deform a tree branch that needs to bend a little bit before snapping apart?

At the moment, I have the branch simulated as an RBD.

[dangerweenie]

Can anyone provide details on how to connect a RBD to a SOP (to deform rigid body sims dynamically)? I've been trying to use the MultiSolver, but no luck. It sounds like a pretty solid plan, but I'm new to Houdini.

[sam.h]

Attached a scene...

Get the impact data into the sop solver and it is great fun

rbdSopMultiSolver.hip

Edited June 24, 2011 by sam.h

[sam.h]

Hey, just found this.

Do you think this technique would be appropriate to deform a tree branch that needs to bend a little bit before snapping apart?

At the moment, I have the branch simulated as an RBD.

Nah i don't think that would work so well, since it will still behave as one object. Give the cloth solver a go ... would be tricky to get the settings how you want though, have a good read through the help for the cloth.

[dangerweenie]

Nah i don't think that would work so well, since it will still behave as one object. Give the cloth solver a go ... would be tricky to get the settings how you want though, have a good read through the help for the cloth.

Thanks for the scene, Sam, checking it out now.

I'm new to Houdini, so the biggest issue so far hasn't so much been theory as it has been syntax and network organization. I've been spending the last couple days exploring how to get solvers to work together cooperatively. The example file "dentingwithpops.hip", is doing (almost) exactly what I need - running a RBD sim, deforming the geo, then having that deformation affect the next frame of the RBD, and so on and so forth.

I'm not a seasoned dynamics guy, but I know enough to say that this multiple solver / feedback thing would be possible, but not as easy in Maya, which I've been using exclusively for seven years.

This program really is fascinating. I wish I had discovered it earlier.

Thanks again for the help!

Best,

Matt

Edited June 24, 2011 by dangerweenie