Storing and sorting through attributes?

[mightcouldb1]

For example, you are coloring a bunch of particles based on their y-position. You want to find the maximum y-position across the entire simulation and make it a value of 1(via fit range), and the minimum y-position for a value of 0.

I usually eyeball the values in the details view while I'm scrubbing the timeline trying to find max and min values. If I was making a digital asset I wouldn't want the user to take this step.

How can I iterate over all of these values and sort them?

[static]

You could do it in python, ie:

geo = node.geometry() # replace node with hou.pwd() in an expression

attr_name = "myAttr"

max = 0

for pt in geo.points():
    attr = pt.attribValue(attr_name)

    if attr > max:
        max = attr

return max

This is designed to be used in an expression most of the time... which doesn't use def statements

See the following for more info:

hou.Point class

Python parameter expressions

Edited March 30, 2010 by static

[aracid]

Hey man

What I did was use the attrib promote SOP and the promotion method to being either "maximum" or/and "minimum", and stored that into a details attribute on the object, and used the details expression to fetch the result from within the point SOP.

I used the time shift because then u don't have to lock ur sim, unfortunately that requires it too sim the whole sequence before u can start messing with it, i wouldnt say its the most elegant solution, but it should work

height.hip

[johner]

One more approach...

Since you want to work with the values of attributes over time, I would probably use CHOPs. Namely, a geometry CHOP set to "Animated" to pull in the values of y across the time range (forcing evaluation of the particles for the entire range, but can't be helped if you're looking for maxima and minima). Then a Math CHOP to combine all the particle Y channels, set to Maximum or Minimum, which will yield the highest or lowest particle y values at any given time. Then a Constant CHOP set to the "icmax" or "icmin" expression of those values to find the max or min across the entire time range.

The problem with TimeShift is you have to know the frame at which the particles are at their limits, which could be tough to know ahead of time.

See attached.

height_CHOPs.hip

Edited March 31, 2010 by johner

[mightcouldb1]

These are all great solutions.

It's nice to see some different approaches!

Thank you all!