Clipping the PRT

Krakatoa for 3ds Max
1

Hey guys,

Is there anyway to clip the prt loader(like level in Photoshop, Low and high threshold in FumeFX). I have been messing around with placing a curve on density in the KCM and cant seem to get good results. I assume its from my lack of experience with magma flow. Is there any other way of achieve this? Maybe without Magma Flow?
Also is there any way to save the frame iterations as its generating motion blur?

Thanks

2

For the clipping, you would have to use the Magmaflow . You would get the density and use that as a criteria for setting the selection channel. Then you would use the delete modifier to do the actual culling.

For the motion blur, you could use Magmaflow to get the position and velocity, scale the velocity down, then add it to the position and save out the result. But the PRT Loader has a time lookup function that would do something similar.

3

I am not 100% familiar with magma flow yet, but I have a 2 color by velocity I downloaded on this forum.How would I go about deleting by the slow color, or making that color a selction so I could delete it in the modifier panel? Any help would be great.

Thanks

4

Magma supports a “Selection” channel which is equivalent to the “Soft Selection” in Max meshes.
So instead of outputting a color, you have to output a Float value into the Soft Selection, then add a Krakatoa Delete modifier above it on the stack.
There are two ways to delete particles - hard and soft. By default, any selection > 0 will delete the particle. But you can switch it so that the soft-selection value defines the probability for a particle to be deleted. This mode requires a valid ID channel though. So a value of 0.0 means the particle lives, a value of 1.0 or higher means the particle should be deleted, and a value between 0 and 1 gives the probability for the particle to be deleted, e.g. 0.5 means 50/50 chance for it to be deleted.

In your case, it would be easier to use the “hard” approach. Simply take your Velocity, calculate the Magnitude, put into a Less Logic operator and compare to a threshold. Then connect the Less operator to the Selection channel output and convert the Less output (which is an Integer of 0 or 1) to a Float by pressing the “Convert To Float” button (assuming you are using KMX2). This way, any particle with velocity below the threshold will set the selection to 1.0 and will get deleted.

In Krakatoa MX 2, you can output to the Color and Selection at the same time, reusing some of your nodes from the color flow to produce the second output.