Reference - Particle Trails
GhostTrails is able to draw trails based on the motion of the particles of a particle system as an alternative to using the animation of a spline object, drawing a trail for every particle.
GhostTrails supports all the particle system types that are included in 3dsmax, including Particle Flow. In general, third party particle system plugins will not work with Ghost Trails.
Use Particle Trails
Check this box to turn on particle trails. GhostTrails will now generate trails from particle motion instead of the motion of the spline object you've applied the GhostTrails modifier to. Note that you won't acutally see anything until you've selected a particle system and regenerated the trails (see below).
Select Particle System ("None" button)
This button is a standard 3dsmax picker button which allows you to select which particle system in the scene to generate trails from. If you have not yet selected a particle system the button will display "None".
To select a particle system, click on the button then click on a particle system in your scene.
Regenerate Trails
Because generating the trails for a particle system is quite computationally expensive, GhostTrails doesn't try to update itself on the fly as you change the animation parameters of the particle system. Instead the trails are generated whenever you press the Regenerate Trails button using the current settings of the particle system.
If you change the particle system parameters you have to press the button again to make GhostTrails pick up the changes.
To make this a little easier to automate, GhostTrails allows you to script the Regenerate Trails function via MaxScript by exposing the regenerate_particle_trails method. For example, the MaxScript line:
$.modifiers[#GhostTrails].regenerate_particle_trails()
will regenerate the particle trails on the currently selected object.
Create Trails
If you don't want to create a trail for every particle you can reduce the number of trails created to one every 2nd, 3rd particle etc. by increasing the value of the Every n Particles spinner.
The Starting at Particle n spinner lets you skip some particles at the start. The main use of this is to allow you to attach multiple GhostTrails objects to the same particle system and have them all generate trails for different particles. For example, if you set up three different splines to generate trails every 3 particles and then set the Starting at Particle n setting to be 1, 2 and 3 respectively on each object, then the first object will have trails for particles (1, 4, 7, 10...), the second for (2, 5, 8, 11,...) and the third for (3, 6, 9, 12...) and so on.
(If you make changes to these settings you need to press the Regenerate Trails button to see the changes.)
Particle Flow Settings
The Particle Flow particle system divides particle generation into one or more Events. GhostTrails can optionally generate trails for a subset of the events in the particle flow system.
If the Use All PFlow Events box is checked, then trails are generated from all events. If you uncheck the box, then only the events in the PFlow Events list will be used to generate trails. You can add or remove events from the list using the Add and Remove buttons.
These settings only have an effect if the particle system you're using is a Particle Flow.
(If you make changes to these settings you need to press the Regenerate Trails button to see the changes.)
Generate Age Mapping
If you check this box, then GhostTrails will generate a second set of UV coordinates for each particle trail in UV channel 2. The U coordinate is mapped from 0 to 1 along the length of the spline used to form the trail.
The V coordinate is mapped from 0 to 1 along the length of the trail depending on the age of the particle at the time the trail first becomes visible. What this means is that a section of particle trail will always have the same UV coordinates once it is generated, and won't change over time.
This sample scene shows an example of the difference between age mapping and regular mapping (3dsmax2009).
Snapshot Path
This button generates a spline object from the paths taken by all the particle trails.