Johan Borgström
Petfactory
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Houdini Skills
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Recent Forum Posts
RBD bullet solver cone twist constraint Sept. 5, 2023, 3:39 a.m.
Thank you for your quick reply!
Really interesting to hear about the improvements in H20.
Regards, Johan
Really interesting to hear about the improvements in H20.
Regards, Johan
RBD bullet solver cone twist constraint Sept. 4, 2023, 4:03 a.m.
npetit
Here's a quick example showing how you might setup some conetwist constraints to use with the RBD Bullet Solver SOP.
Notice I'm only driving a few of the conetwist constraint properties via attributes on the constraint prims.
If you want different settings per constraint for other properties, you'll need to add them as attributes and make sure their default values (which will be multiplied by the prim attributes) on the RBD Bullet Solver are set to 1.
The tricky thing with the conetwist constraint would have to be the motor_target. It's not very intuitive in the slightest. While the parameter on both the RBD Bullet Solver SOP and the ConeTwist ConRel DOP specify a motor_targetr vector param, you need to set a quaternion motor_target attribute. This attribute needs to be updated at every timestep, so make sure you add it to the list of constraint attributes to be updated by the RBD Bullet Solver.
Hi, Thank you for your example file. In the file I noticed the same issue that I had when using a motor_target, that the motion is a bit "twitchy" it does not follow the same smooth rotation that the "driving" motor_target has. You might see in the gif that the visualized motor_target attr has a smooth rotation but the simulated object occasionally slows downs, and speeds up again.
Is there a way to use a motor_target and get a smooth motion?
The reason I want to use a motor_target on the cone twist constraint is do "drive" the wheels of a vehicle. Is there another "preferred" way of doing this. I have tried using v@w on the wheel objects but had some issues with "balancing" the force of the angular velocity.
Does anyone have some tips on how to drive the rotation of an rbd object in a stable and controllable way?
Regards, Johan
Chop lag orient flip Jan. 30, 2023, 2:34 p.m.
Thanks, so then if I would like to get an orient attrib I guess I could lag N and up and then "rebuild" the orient attrib?
The result from lagging N and up is not the same as when I lag orient but maybe this is to be expected. I attached a simple setup, any feedback/tips/ideas on how to improve are always welcome!
Thanks again
/ J
The result from lagging N and up is not the same as when I lag orient but maybe this is to be expected. I attached a simple setup, any feedback/tips/ideas on how to improve are always welcome!
Thanks again
/ J