How to get the animations of the alembic file and make it rigid body

[awie12]

I am really new in houdini. I have an alembic file with animation. I want to get the animation of the alembic and make it rigid body. but somehow when when i make the alembic rigidbodyobject  there is no animations. please help. my scene is like 2 cars crashing with each other. I try the rbdkeyframeactive but its not working.

 

THANKS

[StepbyStepVFX]

Can you share your file ? The problem could lies in many places of your setup...

[awie12]

Here is the test file. I cant figure it out how to use the animation in rigidbody

Test_RIGIDBODY.hip

[StepbyStepVFX]

OK, I understand a bit better what you want to achieve : you use animated objects during first 20 frames, and then switch to simulation.

First : for that purpose, you need a velocity attribute, otherwise, there won't be continuity between animation and simulation. I created it with a trail SOP node, but check what you have in your Alembic. In this case, be careful, your trail will create a velocity based on the point velocity, which is OK for translation, but every point of a solid has different velocity when rotating for example. So check how to have proper velocity on your Alembic.

Second : you need to tell the solver if your object is static (ig. not active), animated static (eg. the solver will update its position, but not simulate it - just "read" the position), or deforming (when the object does not move in world space, but its compoments change in object space). I let read the documentation to understand that.

Third : to switch from animated/deforming static to active, I like to do it in SOP, using a Wrangle node. Check the setup, you'll understand. In the RBDpackedobject node in the DOP, check overwrite active deforming animated attributes, to be sure the solver reads them from the SOP.

Four : check "inherit point velocity" in the RBDpackedobject node.

Run the sim !

 

Test_RIGIDBODY_v2.hip

[awie12]

15 hours ago, StepbyStepVFX said:

OK, I understand a bit better what you want to achieve : you use animated objects during first 20 frames, and then switch to simulation.

First : for that purpose, you need a velocity attribute, otherwise, there won't be continuity between animation and simulation. I created it with a trail SOP node, but check what you have in your Alembic. In this case, be careful, your trail will create a velocity based on the point velocity, which is OK for translation, but every point of a solid has different velocity when rotating for example. So check how to have proper velocity on your Alembic.

Second : you need to tell the solver if your object is static (ig. not active), animated static (eg. the solver will update its position, but not simulate it - just "read" the position), or deforming (when the object does not move in world space, but its compoments change in object space). I let read the documentation to understand that.

Third : to switch from animated/deforming static to active, I like to do it in SOP, using a Wrangle node. Check the setup, you'll understand. In the RBDpackedobject node in the DOP, check overwrite active deforming animated attributes, to be sure the solver reads them from the SOP.

Four : check "inherit point velocity" in the RBDpackedobject node.

Run the sim !

 

Test_RIGIDBODY_v2.hip

wow this is great man thank you so much for the help. I really appreciate it.