Accumulating attribute through sop solver dop

[sparkChan]

hi, everyone. I have a simple scene that a point goes through a sphere, and the point has cd attribute which has a value 1, 0, 0. the sphere rotated along Z. when the point goes through the sphere, the value of cd will be transfer to the sphere and keep unchanged. a sop solver dop can do this I knew, but in my scene, if I use Empty Object DOP, Sop Geometry DOP and Sop Solver DOP to do this, it doesn't work, but if I use RBD Object DOP， RBD Solver DOP and then SOP Solver DOP, it works. but if I toggle "Use Deforming Geometry",it also doesn't work, why?

thanks.

accumulator_spark.hip

[anim]

because it updates geometry each timestep, so your accumulated value is overridden by anything what's in source geo

keep Use Deforming off

and in Sop Solver use object merge SOP to bring your animated/deformed geo and BlendShape SOP to update point positions of your simulated geo (with accumulated values)

I am sure I've posted an example on this several months ago either here or at sidefx forum, I'll try to find it

EDIT: I think this is it

sorry, I am not in front of houdini so I cannot check that or your file right now

Edited April 29, 2011 by anim

[sparkChan]

because it updates geometry each timestep, so your accumulated value is overridden by anything what's in source geo

keep Use Deforming off

and in Sop Solver use object merge SOP to bring your animated/deformed geo and BlendShape SOP to update point positions of your simulated geo (with accumulated values)

I am sure I've posted an example on this several months ago either here or at sidefx forum, I'll try to find it

EDIT: I think this is it

sorry, I am not in front of houdini so I cannot check that or your file right now

hi, anim, I have no idea about BlendShape SOP. Could you show me how to use it in SOP Solver.

I have a particle system which only emits a particle at the first frame and then I got a point when it just collided with animated sphere, and the point only existed in one frame, in other frames it disappeared. so I want to use sop solver to add the point to the sphere, and not disappeared.

thanks

[anim]

here is your file modified for deforming geometry using Blend Shapes SOP

accumulator_spark_deforming.hip

[sparkChan]

here is your file modified for deforming geometry using Blend Shapes SOP

thanks, anim.

As I said above, if I want to add a point to sphere, How should I do?

add_point_to_sphere.hip

[anim]

I am not sure I quite follow

You have a point which at some point collides with the sphere and sticks to it

then you delete it the same frame

and now you want it to be stuck to the sphere?

just get rid of delete1 node

the stuck particle has changed pstate so you can easily distinguish it from free particles

if you want then color the sphere by stuck particles, just attribtransfer attribute in SOPs from them to sphere, you don't need SOP Solver since they have been simulated in POPs

[anim]

but if you want to color your sphere as soon as particle touches the sphere and therefore you keep deleting all other particles

then you can do exactly the same as in my previous file, here is this file modified

PS: above mentioned technique where you keep all stuck particles moving/deforming with the sphere has advantage over SOP solver technique because you can adjust attribtransfer parameters at any time interactively, or instead of using attribtransfer you can cache those particles into a pointcloud and use directly for shading so you can get much detailed paint on surface

add_point_to_sphere_fix.hip

[sparkChan]

I am not sure I quite follow

You have a point which at some point collides with the sphere and sticks to it

then you delete it the same frame

and now you want it to be stuck to the sphere?

right, because when the particle which has a attribute N valued 0,1,0 collided with the sphere, the normal always points up.

however I want the normal rotated with animated sphere.

the picture showes the particle collided with the sphere, and the normal pointed up.

the picture shows the particle stuck to the sphere， but the normal points up corresponding to the animated sphere.

so I think I can use sop solver to add the point to the sphere and become one part of the sphere.

I means I want to get the result the second picture showed.

thanks.

Edited May 2, 2011 by sparkChan

[~nature~]

Hey,sparkChan,

Is this what you are looking for ?

Cheers

add_point_to_sphere_odforce.hip

Edited May 2, 2011 by ~nature~