Hi,

I have created a simple scene: a wall, a floor, a cannon and a cannon ball.
I would like to shoot the cannon ball and break the wall in a realistic way.

I have obtained the right trajectory, and I have learned how to break the wall by using rigid body dynamics.

In a few word, I consider the cannon ball as a static object and the wall as a rbd object. I use “make breakable” on this object and I obtain the effect.

Unfortunately the effect I have obtained is quite disappointing: the cannon ball push the wall away ( a box object) and it drop down like a very light panel. :?


Sometimes the base of the wall starts to break immediately, before the ball touches it. I have understood that the problem here is the contact with the floor ( grid object). And so I have immersed part of the box object (the wall) under the grid object surface, and I have almost eliminated this not so desired effect… but I'm not satisfied of this rough solving. Have you got any better idea?

Another problem is the slowness of the processing by houdini. I have a quite powerful workstation, and a lot of ram, but sometimes I have to wait 3-5 minutes for a single frame. How can I speed the calculation?


My last and main problem is the kind of fractures I can obtain. I'm doing many attempts, and sometimes I obtain a “glass crash effect”, sometimes I obtain large, big fractures (I have called it “marble slab crash effect”… but I'm in trouble when I try to obtain a realistic brick wall crash effect.
Maybe I'm not using the right tool for this kind of job.
Have you got any advices? The simulation is really slow and every change needs a lot of time. Every hint is welcome!

moenen
Hi,
Unfortunately the effect I have obtained is quite disappointing: the cannon ball push the wall away ( a box object) and it drop down like a very light panel. :?

Off the top of my head… Have you played with glue strengths and/or mass? Try increasing the mass on the bricks.

moenen
Sometimes the base of the wall starts to break immediately, before the ball touches it.

Have you tried animating the activation of the Gravity DOP off until the moment of impact?

I love procedural sophistication as much as the next guy, but sometimes, a manual approach is more directable.

I'm a beginner and so my wall is only a single box object. My wall is not made by single bricks… and maybe it's one of my mistakes. I have noticed a tool called “rbd glue objects” , but I'm not using it, at the moment.

I suppose that a part of my problems is caused by the “make breakable” tool. Maybe it's not the best tool for this kind of dynamic effect.

I think it would be the best choice for breaking an object on the floor ( a glass bottle), but it's not the best for the scene I have in mind.

Maybe I should try these tools:

model>break
rbd fractured objects
rbd glue objects

I think to get the most realistic effect you should model a single brick. And build a wall from that. You can write a simple python script that places the bricks as a wall so you do not have todo it manually.

If it is only one object it will break as one object.