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trails on alembic import


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Im working on solving an effect right now, I can create the effect using a simple box, or any other parmetric geo inside houdini, but I can seem to get it to work with an alembic import. 


basically I want to have a range of trails emitting from the surface of an alembic import. I've attempted creating a vdb mesh, coverting, scattering points with a velocity attribute and then using the trail object, but I end up with this. 




the same effect applied to a box or sphere would yield dynamic trails that have forces effecting the points, and inheriting the movement. 


any help would be appreciated. 


even when I get close, I get this. 




for some reason I cant get it to have a variable amount of roots per poly on surface area.

Edited by xcaseyx
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ok, so I have trails on my geo, working good, I spent some time finally reading the H14 documentation. wow so much changed from 12-14. 


so, now Im attempting to some dynamics to the trails, so that the points have particle turbulence, and motion inheritance from the mesh. 



the first part of this is doing basically what Im trying to do on the surface, but Im not sure if it will end up being a dynamic motion trail. 



This feels like something thats been solved many times in houdini, so wanted to pose the question to the forum. 

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sort of, I mean for the most part I have the trails deforming with with some turbulence after wrangling and deleting some of the point + adding in a pointvop to add motion. 


I mainly want to have the trails be dynamic, similar to how hair would be, while still maintaining its length/velocity.


coming from cinema this task is next to impossible, unless you just use its hair system.


my current idea,


generate points on mesh using pointgenerate sop, delete to taste, add a trail sop, set length, use a pointvop to add a noise value to the points themselves?, reintroduce pops to connect the new particles?


still relatively new to houdini, its only been about 6 months, and primarily for fluids.  



Edited by xcaseyx
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thanks I understand the principles of what is happening. That's not where Im having problems. 


also trailing on VDB is problematic, due the mesh shape changing and the fact that the vdb is happening ON frame, it make trails problematic. Again the what the video is portraying is simple, my concept is more difficult. 


import an animated mesh, generate points, trail on those points and have them react as if the velocity and motion of the mesh is effecting the motion of the points on the trails. 


wiggly, turbulent, lines are not hard to generate off the back of my mesh. 

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ok so I have things, inherently working. the streams begin to emit from the object correctly, then they get hit with some turbulence, then I delete points to keep the strand length desirable. 


currently having an issues keeping the streams themselves sticking to the point of emission. http://d.pr/i/1jzVH


as you can see the whole object sorta jiggles around. 


here are some shots of my script. 




and here is my file, if you have any animation source, you can just plug it into the alembic. 



Edited by xcaseyx
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