Problem with Pops in Sop Solver

[hcs]

Hey guys,

I'm working on a particle sim where the particles are attracted to a surface and change the shape of the surface when they hit it. It seems like using a sopsolver for this is a good way to go, but for some reason the attractor in the POP sim doesn't update when its shape changes. I can see the geometry change shape, but the particles are only attracted to its initial shape. I've attached a simple file so you can see what I'm talking about. Any idea what I'm missing here? I'm pretty new to DOPs so any feedback on my setup is also welcome.

Thanks!

pops_in_dops.hipnc

Edited December 12, 2012 by hcs

[bloomendale]

1) You import your data every frame with sop geo dop. But all you need is initial import.

2) You have 2 geo data in your dop object - Geometry and Collider and you need to modify them both. But SOP Solver writes result only to one data. So after first cook you have your points AND modified grid in your Geometry data while Collider data sill imports the same and uses as attractor geo (that's why particles moves to initial position of the grid)

3) Copy spheres on particles in SOPs (after dop import data from dops). Otherwise these spheres will be used as source for particles in next cook.

So i suggest you to import geo through sopgeo only at $CT. And use multiple solver with 2 sopsolvers - one will have particles in it (and write only them to Geometry data) and 2nd will transfer attribute from them and modify Collider data

And here is example scene:

3ak_pops_in_dops.hipnc

[hcs]

Thanks for the thorough explanation, bloomendale. The multisolver solution works great. Just to clarify, when you have some solver in the second input of a multiple solver, can that solver then access any data piped into the first input of the multisolver? Also, what does the "rendering parameters volatile" node do? I've never seen it used before.

Thanks!

[bloomendale]

1) green (data) input of multisolver accepts only solvers as subdata and yes, if you have several solvers attached then second solver can operate on result of the first solver and so on. So changing positions of the particles in first sop solver i then read them in second sop solver to transfer to grid.

2) By default only Geometry data are visible in viewport in dop network and even can be rendered. If you want to visualize (or render) some other data of the type SIM_SopGeometry or SIM_GeometryCopy you need to attach RenderParms subdata to it and render param volatile dop does it for you.

p.s. I don't think you have to use dops for such things. Try using Solver SOP in sops (which is actually dopnet with sop solver dop in it, but created and managed automatically).

[hcs]

Thanks again. The Solver SOP would work at this stage of my project, but I think it would become cumbersome before too long and I need to learn to use dops better anyway.