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Workflow for lots of RBD in a DOP?

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First of all, sorry for my english writting skills because it aren´t so good :)

I have been making a simple domino simulation with 1000 pieces like the one of the Houdini 10 Blast Off Promotional Videos. :)

I am making it with ODE, but I don´t know if I am doing something wrong or simply it is normal that it could take a minute per frame in dops calculations. :huh: It is not neccesary to make it in Ode but I thought it could be the best way.

I tried to bake the simulation to .sim files but it takes long to write 200 mb files per frame. Also I read in Houdini help that I can bake parts of the simulation with this method and use it to affect other sims but I don´t make it work.

How can I speed up this simulation?

Thanks in advance and sorry again for my poor english


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What is your computer's configuration ? Because with mine, Eight 2.4Ghz Cores ( only one is used for the simulation ) and 4go of Ram, it didn't take so long to process.

To optimize the sim, you could do the following things :

. In the collision tab of your rbd point object, change the collision methode from raytrace to implicit box, and reduce the resolution. ( You can use the show collision geometry tab to see how your collision object looks like. To avoid waiting too long between tweaks change your number of points to something about 2 or 3, then tweak the parameters until you get something right, turn off the show collision geo tab and increase your number of points to the old value. )

. remove the static solver under the ground and change the merge node from mutual to Left affect Right.

. add an rbd auto freeze node after the rbd solver, to avoid sim objects that are not moving anymore.

To write the sim files out, don't forget that you can gzip them. Simply use something like ' $HIP/SIM/MySim.$F4.sim.gz ' and houdini will zip them automatically and unzip them the same way when you read them. Remember that writing the sim files slow down the sim, so depending of what you're looking for, you could write the bgeo sequence using a rop sop or a dop i/o sop.

Here is the corrected scene. I've corrected also the first point velocity and changed it from (3,0,0) to (0,-2,3) in order to make the first domino fall into the second.


Edited by Div

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Thank you so much for your help, Div. I have been working on my scene with your tips. I get a better performance when I tune properly the auto-freeze dop.

However, I can´t get a real-time simulation in my viewport even writing the sim files to disk (compressed or uncompressed) so I am doing flipbooks.

My computer is not bat, Core 2 Quad 2.83 ghz, 8 gb RAM, Vista 64-Bit, Nvidia GTX280 (1gb) 1TB Hdd. So I supposed it will work better.

Now I am lookoing for other utilities for the autofreeze dop. I think it could be very useful for other tasks if I can use the Cumulative Movement data for activating the gravity in a per-object basis, for example.

Any ideas of how to do this?

Thanks again and sorry for the grammar mistakes.

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