Ali Rizvi

figured so thought of sharing it here..

you can basically split out each element and manipulate it, I just realized the correct way of visualizing orient is by turning on axis on each point (under visualization style) .. inside vops you can bind orient in and connect vector4 to vector that ll give you all 4 values (1 vector OR 3 floats with an additional float value ), again drop a vector to float and split the xyz axis, now you can pick any axis along which you want to randomly rotate the orient (in my case I use z axis because I am aligning things up based on that), again float to vector 4 and you can add or multiply between the vector to float and this float to vector 4, connect 4th value from the vector 4 to vector , bind it back to orient and done.

I have a particle Sim, I am copying some geo's on it, everything is oriented nicely, what would be the best way to manipulate the orient so that I can randomize the rotation of my orient vector in z-axis, I've tried creating a new vector based on my up and normal (perpendicular vectors) and double cross it with up to create an axis which I used to multiply the rotation matrix but it has a very slight effect unlike when you do a rotation matrix.

In short how would you rotate a orient vector before copy node.

sure, you wont be able to get detailed surface results with higher particle radius (that is why its not a preferred way if you dont want to compromise your details). What version of houdini are you using and what is your system configuration, this looks fairly straight forward sim and shouldn't take over night to calculate as long as you are on a very slow system.

I would increase the particle count in the source if I want the fluid to collect at the wall and add a bit friction to the collision geometries , make sure you are using vdb's for collision, they ll make your sims faster.