I am trying to use the PRT pflow birth operator in conjunction with afterburn to make some clouds. But I keep getting flickering particles, ie random particles that change their position from frame to frame, and by random position I mean not where they should be on the next frame but some random position in space that looks like a flicker of some sort. I am not sure why this is happening and was wondering if anyone had run into this before or if this is just normal behavior for this.
I am using a prt birth operator and an update operator to get the velocity and move the particles based off the velocity data in the prt. I was able to lessen the effect by using a group selection operator by id and setting a limit to the amount of particles in the PRT but this only served to lessen the flicker effect but I am still getting it.
Attached is a qt so you can see what I am talking about.
Is the particle count changing in the PRT files? If yes, you also need a Krakatoa File ID Test operator connected to an Event containing a Delete operator to delete any particles that have died in the PRT sequence.
Also, does the PRT sequence contain a valid ID channel? Without it, neither of the 3 operators (PRT Birth, Update, File ID Test) will work correctly.
You leave it at default settings. Basically we read the ID channel of each particle and when it is born from a PRT file, we record that birth in the File ID channel (internal to our operators) by setting it to the ID channel from the PRT file. When the next frame is loaded, we look in the PRT file for particles that are NOT in the File ID channel of Particle Flow, and give birth to them. This way, we make sure that only NEW particles that we have not seen yet are being born on each frame. At the same time, we look if a File ID of an existing Particle Flow particle is NOT in the next PRT file. In that case, we know the particle should die now, and we set its File ID channel value to -1.
The File ID Test looks for Less Than 0 by default, so it sends out any particles that have been marked as “dead according to the PRT sequence”. If you don’t send them out to a an Event with a Delete operator, they will stay around, but won’t be updated anymore because they don’t exist in the following PRT files anymore.
I am not claiming that the lack of a File ID test is the cause for your issues, but if you do have changing particle count in your PRT files, you MUST have a File ID test sending out to a Delete event.