I stuck really hard with particles expression weirdness...
we could use particles id`s as variable to produce some things with each particle individually in particleExpression node.
for example if in Position field we enter v(id,0,0) - we get straight line of particles. one by one. - and i like it!.
So for my effect i need to go little more further, i want pick a color value from an another image and use it as particle position for example.
You can say : ok, whats problem?
actually no problem were thought i too.. we have an amazing "sample" command!
BUT - it doesn` work.. it just didn`t see "id" value.. Nuke told me that he don`t know any "id" variables!
[sample some_image red 10 0]
example (i get error message with it : ERROR: ParticleExpression1: Nothing named 'Nothing' in 'Nothing is named "id"'):
[sample some_image red id 0]
But funny thing (not so funny actually )
[sample some_image red [id] 0] - its working! but not as you can suspect to be
So guys, if you have an ideas how to get "sample" to work per particle id`s - help me please, i need it so much.
or may be there is some alternative way to set position for each particle based on external(not in the emitter flow) image color.