tracking an attribute on a geometry with changing point count

[bhaveshpandey]

Hi, I have mesh extracted out but it doesn't have attributes I need. I have the fluid particles with me though, but remeshing them is not really feasible at the moment. I was thinking if I could accumulate the attributes myself using a sopsolver?

Issue is that the mesh(which is deforming) has changing point count and I am not really able to get the attribs to accumulate.

When I attach the geometry data and set the SOP path and Time to "Set Always", the accumulation doesnt happen. I'm guessing that geometry gets refetched from

SOPs which is not updated. Which makes it overwrite the accumulation effect?

Is there a way around this?

here a test file demonstrating this.

SopSolver_ChangingPointCount.hipnc

[anim]

here is fix for your file

the key is to import attribute from nearest point of previous frame geometry

so it doesn't matter if point numbers are changing

(if you have faster moving geometry or jittering topology then maybe you better attribtransfer that attribute with some radius instead of copying just from closest point to get smooth result, but principle is the same)

SopSolver_ChangingPointCount_fix.hipnc

[bhaveshpandey]

Thats a smart fix! so instead of using set always at the dop level, we are calling in the deforming geometry within the solver itself.

Thanks

[eetu]

(if you have faster moving geometry or jittering topology then maybe you better attribtransfer that attribute with some radius instead of copying just from closest point to get smooth result, but principle is the same)

Or maybe try and figure out point velocities, and transform the previous frame's points with their v attribute before attribtransfer.

[bhaveshpandey]

Thanks guys. I had to upres the sim so ended up fixing the issue in the sim itself. Now I can just render it out (provided I can finish the shader )

Position based methods are very handy indeed.

@eetu I'll keep that one for another test. sounds possible and handy for such situations!