[Sidefx-houdini-list] Particle Flow

Dan Seddon dan.seddon at framestore-cfc.com
Fri Mar 31 10:15:49 EST 2006

Ben Schrijvers wrote:
> Basicly what you need to do to enable mixing your curve control with 
> forces is modifying the acceleration rather than velocity.
> Most of the other POP's work on acceleration as well and velocity is 
> something to be very carefull with.
> But you can't just use the attributeTransfer POP as this will 
> overwrite the existing acceleration.
> Also the acceleration that you need to apply is the difference between 
> the curve velocity and the velocity of the particle.
> So transfer the velocity to a custom attribute, subtract the particles 
> velocity from it and add it to the existing acceleration.
> You could do that with an expression in an acceleration POP.
Yep a controllable way of doing this might be to use Attribute Transfer 
in combination with a Pop Vop. Use attribute transfer to find the 
nearest point on the curve then make a Vop which produces an 
acceleration or force which drives towards this point - you can also use 
this positon to give yourself a nice falloff with distance. You could of 
course use an expression - but I figure a Vop is easier.



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