Cliff edge crumbling under weight of drifting car

[AC5L4T3R]

Hey Guys,

As some RND, we're creating a series of animations at my company that'll be a test project for switching to Maya from 3ds Max as our main production tool. One of them has a car drifting around a road (think Pikes Peak) and I want to create an effect where the road edge crumbles under the weight of the car. I've been following the Applied Houdini Ridigds tutorials along with some others but generally don't touch what I want to do, but currently I don't know enough about Houdini to work out what to do. 

So, what I want to do is the following:

 

• Specify area of cliff that will be fractured - Either by selection or painting
• Have fractured area crumble as wheels drift on said area.

Simple, right?

If anyone could show me an very basic, quick and dirty set up for me to build on, that'd be perfect.

 

Cheers!

[jamesr]

You should be able to get what you're looking for with a combination of Attribute Transfer/Sop solver to activate your pieces based on where the wheels are skidding, and the detailed boolean sim setup from the Applied Houdini Rigids IV (though I haven't watched it, so I'm not sure if you can use *exactly* the same methods and stuff). You can import the animation of your car, isolate the wheels of your vehicle, give them a red color and give your ground a black color. Fracture the ground/cliff area. As the wheels skid across the ground, they leave the red behind, and everything with a red value > some threshold will receive an "f@active" attribute value of 1. In the RBD sim, those pieces will then respond to forces and such, and you can have a gravity force and/or some custom point velocities to throw the pieces around in a fun way. Or you could use constraints (glue, or better yet cone-twist might look cooler since it will allow for some flexing and twisting before the pieces break away fully) to keep the pieces held together, and as the car skids over, the constraints start to weaken and break, causing them to crumble down.  

Here's a few links that might help: 

CG Wiki:: Houdini DOPs - A little over half way down the page has some RBD stuff, and different ways of activating them. 

CG Wiki:: Solver SOP  - Everything on this page is important. 

CG Wiki:: Attribute Transfer - These examples show how transferring attributes work. 

Deleting glue constraints with color

The Applied Houdini rigids I & II should give a good foundation, and I know in IV  he does some cool stuff with the boolean sop which looks pretty nice. 

I hope the rough description helps a bit as I can't post a hip at the moment.  Those links should help, and I'll try to throw something together when I get home if there's time. It helps to have a general direction to follow, since the scope of houdini can be quite large.

 

 

 

[AC5L4T3R]

Thanks James, I'll give those links a read over the weekend. I'm going through the Dynamics tutorials again to refresh my memory. Hopefully I can work something out over the weekend also and I'll post the file if I get something going.

Edited March 16, 2018 by AC5L4T3R