AWS Thinkbox Discussion Forums

normals on nParticle

Hi, I am having an issue where I can get my magma flow to work when I wanna get the vel channel into color, bot I’m not getting the same results with the normal

When I made my PRT partitions I did enable normal, I feel there is something I am missing

When you enable the Normal saving in the PRT saving dialog, it does not generate a Normal value for you. It just maps a per-particle channel to be saved in case you defined one yourself. So you will need to write some expression to grab an axis from the particle’s orientation (or whatever else calculation you might want in order to define a Normal vector) and stuff it in, say, the normalDirPP channel, then save your particles to disk with Normal checked in the dialog.
Please let us know if this helps.

As Bobo mentioned, your nParticle system will need to provide a float[3] per-particle attribute named “normalDir” or “normalDirPP”. That gets mapped directly to our Normal channel in Krakatoa.

I would actually like some feedback on how we are doing it, because it is slightly unclear to me how Maya users typically generate normals for particles… Or if this is ever done. Does using the “normalDirPP” attribute work in this case?

For comparison, in 3ds Max / Krakatoa MX we simply take the X axis from the particle’s transformation matrix (which can also be extracted from an Orientation channel) and we export that as the Normal. This is because 3ds Max Particle Flow assumes particles’ X axis should be aligned to the Velocity when you ask for a Velocity Space Follow behavior. We also assume the Y axis to be the Tangent.
I guess we could do something similar in Krakatoa MY?

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