How to keep object stationary until collision?

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I am experimenting with dynamics, making an object remain in place until another object collides with it and then it falls with gravity.

Is there a better way than connecting a Gravity node to the object to be temporarily static and keyframing its force from a positive Y value (to counteract another global Gravity node) to 0 at the frame of collision? In Maya you can activate the dynamics of objects on/off simply.

OK,Ive discovered the Active Value node. This lets you turn dynamics on/off on individual objects. Seems to be the method.
Edited by litote - Feb. 26, 2020 00:33:52
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here's a basic one with RBDsolver SOP

The 1st object into merge is the AGITATOR, named piece0.
Edited by vusta - Feb. 26, 2020 01:44:51

Attachments:
SleepingBalls.gif (354.6 KB)
vu_RBD Sleepers.hiplc (613.4 KB)

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Thanks but your scene file crashes my Houdini app (17.5).

What is your method, do you use an Active Value node?
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litote
Thanks but your scene file crashes my Houdini app (17.5).

What is your method, do you use an Active Value node?
if you're using Apprentice…I don't see why you should be stuck on 17.5

c'moooooooooon get on 18 and get all the goodies !!!!

(it's ‘sleep’ property)ie. if nothing impacts you…you stay asleep forever.
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Tanks, I will upgrade eventually. I will keep your file for when I upgrade. Is the sleep property only in v18? Where would I look for it in a node or what should I look up in the manual?
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hmmm..I just opened my 18 file in 17.5…the copytopoints in 18 is somehow interpreted as merge in 17.5

but once that's fixed…all work as expected.

so you'll see in configure, everyone is set to sleeping, except for the AGITATOR of course.
Edited by vusta - Feb. 26, 2020 21:07:28

Attachments:
vu_RBD Sleepers_17.5.hiplc (1.6 MB)

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I can't open your file. It crashes. Can you just tell me what I should look up in the manual for the “sleep” property?
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c'mon, seriously…I've had to go back do it in 17.5 gave you a 17.5 file…like cmon.

https://www.sidefx.com/docs/houdini/nodes/sop/rbdconfigure.html [www.sidefx.com]

can you not simply get 18 Apprentice ? it's FREE.
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Thanks, much appreciated. I don't want to get the Apprentice version and I don't want to risk having problems with installation, as has happened before. For now I will stick to 17.5. But I am glad you showed me the RBD Configure SOP so I can study it. Sorry to take up more of your time. Don't know why your file crashes my version.
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just fyi, the 17.5 I used was 17.5.425

so maybe your 17.5 is a bit older ? dunno.
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That might be it. I have held off updating it but I probably should.
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