HI,
I try to use the bullet solver inside Houdini.
I create my simulation with fracture and the fracture pack, but when I simulate it some pieces compenetrate another, why? How can I fix it?
thank you so much
Mat
p.s.: add scene and images
Bullet solver interaction objects
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- MatEvil
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- Nima
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Hello.
Simulating these types of simulations always been a challenge!
Most of RBD engines use similar methods for reducing sim time hence sometimes and in some simulations we dealing with penetration.
Bullet engine has convex hull geometry representation in which objects has convex hull shape around of themselves.
you can use Houdini native RBD engine it's precise but takes much longer to calculate.
If you insist on using Bullet, you have to choose concave geo representation or implement a little bit tricky method like following HIP file.
Thanks.
Simulating these types of simulations always been a challenge!
Most of RBD engines use similar methods for reducing sim time hence sometimes and in some simulations we dealing with penetration.
Bullet engine has convex hull geometry representation in which objects has convex hull shape around of themselves.
you can use Houdini native RBD engine it's precise but takes much longer to calculate.
If you insist on using Bullet, you have to choose concave geo representation or implement a little bit tricky method like following HIP file.
Thanks.
Edited by - April 7, 2016 07:35:57
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- MatEvil
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HI NimaNolan,
thank you for your message… and yes! is always a big challenge with rigid body sim in all software.
So native Houdini RBD Solver is “rigid body solver” with type “solver engine RBD” ?
I see by default is Bullet so I use a bullet solver alone, but try to understand your file
- ok, you separate fracture/debris to other part.
- why you use “unpack” before the “for each” ? Because I use “assemble” node with the check on “create packed geometry”… (?) maybe you did that for create a centroid expression and center the pivot in the center of all objects right?
- why you need a create another voronoi fracture on the second element?
Can I use it in one-block without another voronoi node?
Thank you for your time, I will only understan and I know maybe my question is more long….
Matteo
p.s.: I continued with my test
thank you for your message… and yes! is always a big challenge with rigid body sim in all software.
So native Houdini RBD Solver is “rigid body solver” with type “solver engine RBD” ?
I see by default is Bullet so I use a bullet solver alone, but try to understand your file
- ok, you separate fracture/debris to other part.
- why you use “unpack” before the “for each” ? Because I use “assemble” node with the check on “create packed geometry”… (?) maybe you did that for create a centroid expression and center the pivot in the center of all objects right?
- why you need a create another voronoi fracture on the second element?
Can I use it in one-block without another voronoi node?
Thank you for your time, I will only understan and I know maybe my question is more long….
Matteo
p.s.: I continued with my test
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- Nima
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So native Houdini RBD Solver is “rigid body solver” with type “solver engine RBD” ?
yes, exactly.
- why you use “unpack” before the “for each” ? Because I use “assemble” node with the check on “create packed geometry”… (?) maybe you did that for create a centroid expression and center the pivot in the center of all objects right?
Your geo representation set to convex hull which means holes of sphere ignored by bullet solver(as we can see in your image) and this is why fractured pieces penetrate each other!
I created centroid expression to make pieces a little bit smaller around pivot point of each object(just for sure that we not getting any penetration).
- why you need a create another voronoi fracture on the second element?
Can I use it in one-block without another voronoi node?
I use another voronoi fracture node for geo representation Correction see following picture.
Of course you can do it with one voronoi fracture node but in bullet geo representation you have to choose concave(but concave makes your sim unstable and slow).
cheers.
yes, exactly.
- why you use “unpack” before the “for each” ? Because I use “assemble” node with the check on “create packed geometry”… (?) maybe you did that for create a centroid expression and center the pivot in the center of all objects right?
Your geo representation set to convex hull which means holes of sphere ignored by bullet solver(as we can see in your image) and this is why fractured pieces penetrate each other!
I created centroid expression to make pieces a little bit smaller around pivot point of each object(just for sure that we not getting any penetration).
- why you need a create another voronoi fracture on the second element?
Can I use it in one-block without another voronoi node?
I use another voronoi fracture node for geo representation Correction see following picture.
Of course you can do it with one voronoi fracture node but in bullet geo representation you have to choose concave(but concave makes your sim unstable and slow).
cheers.
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- MatEvil
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OK!
thankx a lot for explain all…. so… one big tips “Concave so instable, use another way”
right?!?!?!
OK, so… now I try to continued with my test and I hope to post something in the next time. By the way now I continued to study with this 2 video
https://www.sidefx.com/index.php?option=com_content&task=view&id=2350&Itemid=132 [sidefx.com]
https://www.sidefx.com/index.php?option=com_content&task=view&id=2622&Itemid=132 [sidefx.com]
have a nice day
Mat
thankx a lot for explain all…. so… one big tips “Concave so instable, use another way”
right?!?!?!OK, so… now I try to continued with my test and I hope to post something in the next time. By the way now I continued to study with this 2 video
https://www.sidefx.com/index.php?option=com_content&task=view&id=2350&Itemid=132 [sidefx.com]
https://www.sidefx.com/index.php?option=com_content&task=view&id=2622&Itemid=132 [sidefx.com]
have a nice day
Mat
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- Nima
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- MatEvil
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- Nima
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- MatEvil
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- Nima
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- MatEvil
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- MatEvil
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- MatEvil
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- MatEvil
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