How can I get RBD objects to be created from a particle source, and use the instance geometry to do the collisions? I'm trying to make a bunch of objects fall and pile up over time realistically but so far i can only get the particles themselves to collide, and not the instanced geometry. Needless to say this looks horrible in this case. i've tried RBD to point tool on the particles but everything disappears…

hi there,

I had a little spare time so I created this example scene for you,
don't hesitate to ask if you have any questions!

all the best,

Manuel

thank you! i will look it over after i get some sleep :shock:

ok so basically you copy the balls to the particles and then put an attribute on the particles to separate them into two groups, and kill off the particles inside the spheres before sending them to the dop network? i dont quite understand the if statement though, where did the attribute for the particles get set to >1?

it's quite simple:
when the attribute $groupchange is created, the default value is set to 0.
As soon as the particle's life reaches a certain value, the default value get's overwritten by the current frame.
>1 makes sure the particle's attribute has been replaced by the frame and
$F == $GROUPCHANGE + 1 is set so the particles gets killed exactly 1 frame after they enter the group.
Try not to delete them and you will see in the DOP network you get every frame a new copy for each object, so deleting them this way is really necessary!

regards,
Manu

Hi Manu

I really like the way you are work, keep it up.
I have a simple question about your network, in copy sop you activated use template Points Attributes, which is groupchange v. what for is v.

cheers

thanks man, nice to get some feedback
v is the point velocity attribute!
I transfered the v attribute to the copy SOP because later on in the RBD fractured object you will see that I activated “Inherit Velocity from Point Velocity” to inherit the motion from the falling particles.
that's it!

cheers

ohh …. so you transferred 2 attributes ( groupchange, v ).
I should notice that.

cheers

waiting for more videos

this is almost completely clear to me lol. i just dont understand WHY the groupchange attribute gets set to the frame number. when does it pick up this information?

ok i guess i didnt look inside the pop network. i see the if statement setting it based on life. why did you choose .32 and .33 for the life values? is this an arbitrary setting you have to experiment with based on your simulation?

I set the expression to
if($LIFE >= .32 && $LIFE < .33, $FF, $GROUPCHANGE)
because strangely $LIFE == .32 didn't work! (don't know why!)
try for yourself

Another approach for this would be to create a plane in the scene and
add a collision node in the POPNET. Then you could create an Attribute called “Hit time” which would give you also the frame number each time the particles collide with the plane.

ok this is what i ended up with to get something like coins falling and piling up. i added an rbdfreeze op and bumped down the collisions resolution to keep the simulation going at a decent speed. any other suggestions to make this simulate any faster?