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Hello all, this is my first time posting on here so greetings. This is a cross post also on the Houdini forums here:

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=27451

I have been working on a tool that takes an input curve and adds velocity to it for use in a Pyro sim (also FLIP but first getting it to work with Pyro). I have been working on this tool to help give the artist an easy way to direct a Pyro sim along a curve.

Here is an example of how it is currently working:

https://vimeo.com/55189800

Here is a screen cap of how I have implemented the use of the tool:

https://vimeo.com/55238678

I'm also including my otl and an example file.

I would like any feedback as to ways to improve the tool or other/better ways of accomplishing similar effects. I greatly appreciate it.

Thank you much.

example.hipnc

NU_curveToVel.otl

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You can use vops instead of scattering in volume. It will speed up things up to several hundred times - from 1+ sec to 0.002 =)

And using even 200 divs in isooffset produced artifacts in volume (and in scattering) with fairly simple curve. Don't know why tho.

m_20121215-qvh2-53kb.jpg

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Your work is really interesting Nate, thank you for your files. I will try to give you my feedback

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Thank you Adrien :)

Bloomendale - Thank you, that is really helpful. I'm trying to rework it in Vops now and I think it will end up working out much better and faster :) I will post back when I get more put together.

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After reworking the tool in Vops I am very pleased with how much faster it is cooking. I am instead within the Vopssop taking normal tangents and displacing the points along those vectors which in turn gives me more control.

I still of course welcome any feedback, suggestions or critique.

Thank you.

I have not posted any more tests yet but a screen cap of the tool use found here:

https://vimeo.com/55833089

post-8826-0-47242700-1355806501_thumb.jp

post-8826-0-44943700-1355806502_thumb.jp

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Hey Nate,

Nice otl one suggestion i can think of is adding a vortex throughout the curve, I know the quaternion vop can do this but not sure how to orientate it throughout the curve. Maybe someone has an example ??

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bumpin this! :D

can anyone explain how you would add a vortex throughout the curve?

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Get a point cloud along your curve, there are many ways you can do this - I guess the easiest is to build a a tube using your curve (polywireSOP) and scatter points inside (PointsFromVolumeSOP) and then use a VOPSOP or PointWrangle to get the position of your each point and cross product this with the position of closest point in the curve (PointCloudOpen and PointCloudFilter) - Normalize both before the cross product.

TIP: You can use a ramp for distance from the center to control how strong your vortex will as getting closer to the center.

bumpin this! :D

can anyone explain how you would add a vortex throughout the curve?

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can anyone explain how you would add a vortex throughout the curve?

I've been working on a project that required something similar to Nates tool, with a vortex. I think its even faster when you use volumes from the start, instead of converting vector point attribs into volumes. Here's quick example of how I did it.

vel_vortex.hip

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Is there a way to get Your tool to get the velocity of particle that didn't come from a curve

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Thank you all for the comments. I'm going to jump into doing this with a total volume approach soon. Did not notice any of the comments until just the other day.

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There are many ways to get particle velocity. For instance you could bring them into a dop using field force dop with a sop vector field dop.

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Thanks a lot for this Nate

I was trying to recreate the tool, and I think I've done it completely, but whenever I add points on my top-level ramp, the the sublevel vop ramp doesnt recognize that a new point has been created.

how did you link your top-level ramp settings to the sublevel exactly?

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