The PathFollow operator lets you choose one or multiple paths and make the particles follow this path. The coolest feature however, is that you can not only select a spline object as a path, you may also select an edge or edge loop to act as a path on a surface!

ON (Bool) - This input data stream determines whether the operator is considered 'on' or 'off'. You can connect other operators to this input channel such as a Bool Helper to activate/deactivate the whole operator.

Time (Time) - This input data stream is used to define the local time for the operator when the user wants to override the default system time.

Particle (Particle) - This input data stream reads in the currently selected particle group that is to have its particles follow the selected node. The data stream MUST be connected and will be highlighted yellow if it is not.

Path ID (Integer) - lets you select a path for the active particles that they should follow. This is needed if more than one path is selected.

Type (Integer) - used to switch between Absolute follow or relative

• 0 = Absolute
• 1 = Relative

  UI Control Parameters - those input data streams are the equivalent of the UI controls, keep in mind that there is no visual indication that an operator is connected to any of those inputs! It might be needless to adjust a value if it gets overwritten by a connected operator.

No Operator Outputs.

Up - Click on the UP button to move a selected object up within the Follow-Path list window.

Down - Click on the DOWN button to move a selected object down within the Follow-Path list window.

Remove - Click on the Remove button to remove a selected object from the Follow-Path list window.

Pick Object - Click on the Pick Object button to enter the pick object mode. Once active, you can select any valid 3ds Max object and use it as a path. Keep in mind that you can!

Hide - click this button to Hide/Unhide the selected path object in the viewport. 

Absolute - check this option to make the particles lock onto the exact path position of the selected object.

Relative - when checked, the particles will follow the selected path object relative to their current position.

Start Position - used to add a positive or negative offset to the starting position. You might have created circular paths (a roller coaster for example), in such a case the starting position is not really defined. Use this parameter to shift the starting position of the particles forward or backward along the path.

Variation - specifies a random variation that will be added or subtracted on top of the Start Position value.

Distance - offsets the particles away from the path. Particles can be shifted up or down from the path follow object. In the case of a selected mesh object with an edge selection, the attached surface normal of the selected edge defines the direction of the shift.

Variation - adds a random value to the Distance parameter. This can be used to prevent an unnatural equidistant look when all particles have the same distance form the path.

Rotation - lets you rotate the particles around the path follow object.

Variation - adds a random variation to the Rotation value for each particle

From Particle - check this option to use the initial speed of the particle as a start for the follow operator.

Defined - when checked, the parameters described below will be used to define the initial particle speed for the path follow operator.

Speed - defines the initial Speed of the particle that follow the path.

Variation % - adds some random variance to the Speed value.

Vertical X,Y,Z - sets the vertical (90? perpendicular to path) orientation of the particles that follows the path. Lets say you see a circular path while looking from the top viewport, vertical would mean the direction poking into your eye! Or if you sit at the particle's position it is the UP vector.

Invert - when checked , the orientation of the selected axis becomes inverted.

Path X,Y,Z - defines the path's direction in relation to the particle. Imagine sitting in a roller coaster, the path-axis would define the driving direction of your particle.

Invert - check this option to invert the path-axis setting.

PathFollow can be used to make multiple particles follow a path in an ordered manner like a roller coaster or train. This operator lets you set a fixed or a variable distance between each particle.

From Particle - when checked, the original object/particle distance will be used to place and move the particles on the path.

Defined - check this option to specify a fixed and locked distance between the particles following the path.

Variation % - adds a random variation on top of the Distance value.

Group - select the group that will be used to define a fixed or variable distance between particles. Specifying a group is only needed when Connected is activated; in all other cases the particle input of the operator is enough. On the other hand if a group is specified, no particle input is needed.

Connect - check this option to lock the particle to a fixed distance as defined in the Distance parameter. All particles following this path will be locked to this certain distance.

PathFollow offers one special case for defining a follow path for particles, any mesh edge selection can serve as a follow path. It should be clear that the edge selection must form a continuos path along the objects surface.

As you can see in the example below the “inner” edge loop was selected to form the path the particles should follow.

Using a continuos selection of edges in a mesh offers many advantages over simple spline paths. Using the mesh supplies important information about the orientation and rotation of the path in 3D Space. Creating a roller coaster “looping” or even a cork screw looping is not possible in 3ds Max by using splines, only. Right now, only a mesh can supply the correct 3D orientation in space to make a roller coaster wagon follow the exact loops.

Standard spline objects as they are used in 3ds Max do not have normals attached to them, this makes it impossible to align an object along a “twisted” spline for example.

thinkingParticles will “detect” the edge selection and it will automatically use the selected edges as a spline path to make particles following it.

Forces like gravity, friction or wind are legal to use with this path particle path constraint. Those forces will be added in a physically accurate way, making it possible to do a real world roller coaster simulation!

Path - check this option to define the selected object to be already a path (Spline objects)

Selected Edges - when checked, the selected object must be a mesh with an active edge selection. Those selected edges will become the path.

Invert - check this option to reverse the path direction.

Base Axis X,Y,Z - select either axis to define the main alignment that should be used for all further particle alignment processing.

Rotation - specify any angle, to freely rotate around the perimeter of the path.

Ticks per Unit - defines the maximum resolution of the time samples possible along the path length. This value is only used when a mesh object, with selected edges, is chosen as a path provider.