Attracts or repels particles using a referenced Force SOP or Point SOP.
The magnitude of the referenced force determines the how much the force attracts or repels the particles, but it interacts with the mass and charge attributes of the particles (if a particle is negatively charged the effect of this operator is reversed), unless you use the Ignore charge and Ignore mass options.
To apply a global force to particles, use the Force POP.
You can use a SOP connected to one of the POP networks inputs as the attractor, or reference an arbitrary SOP, according to the Attractor use parameter on the Attractor tab.
Using an input gives you the flexibility to easily change which geometry to use for the attractor, either manually or programatically.
Using an explicit reference is useful when the attractor geometry is in a known location and is not expected to change.
This force is similar to the Follow POP. This tool should be used when you want to attract particles to a static object, whereas the follow tool should be used when you want to attract particles to a moving object.
This operator modifies the
Select the particle system you want to be attracted or repelled.
Click the Attractor tool from the Drive Particles tab.
Select the object you want the particles to be attracted to or repelled from and press Enter to confirm your selection.
The degree of attraction/repulsion can be modified in the parameter editor.
Turns this node on and off. The node is only active if this value is greater than 0. This is useful to control the effect of this node with an expression.
Note that this is activation of the node as a whole. You can’t use this parameter to deactivate the node for certain particles.
How the points of the attractor affect the input particles.
Specifies the SOP to use.
Path to the SOP (when Geometry source is set to Use Parameter Values).
|Ignore Transform Object|
Particles normally use the object space of the SOP being cooked. Turn this parameter on to not transform into the space of the cooking SOP.
|Stop At Attractor|
Particles stop when they reach the attractor.
Multiplies or divides the force of the attractor.
|Show attractor radius in guide|
Shows the radius of the force as part of the node’s guide geometry. Turn on the node’s template flag to see the guides.
|Show acceleration in guide|
Shows the applied acceleration as part of the node’s guide geometry. Turn on the node’s template flag to see the guides.
Ignores any charge attributes on the input particles.
Replaces any charge attributes on the input particles with the value of the Charge parameter below.
Charge to use when Override charge is on.
Ignores any mass attributes on the input particles.
Replaces any mass attributes on the input particles with the value of the Mass parameter below.
Mass to use when Override mass is on.
The parameters on this tab add randomness to the attraction force. This makes particles more or less attracted at random, creating a less uniform effect.
Seed value for the random turbulence generator.
Number of iterations of fractal noise to add.
Scale of noise added with each iteration.
Noise attenuation exponent.
Spatial frequency of noise field in X, Y, and Z.
Maximum value of noise field.
Amount to shift noise along X, Y, and Z axes.
Method used to generate noise. Hermite Interpolation and Improved Hermite are fastest.
Standard POP local variables
The seconds a particle in the template has been alive.
|AX AY AZ|
Acceleration of the particle.
|BBX BBY BBZ|
The point’s relative position in the bounding box.
Point is dead.
Processing iteration number.
A collision for this particle was detected (for example, by the Collision POP) during the processing of this timestep (that is, this iteration of the particle simulation). This variable is cleared at the beginning of each timestep. Note that the collision POP actually detects any collisions which would have occurred the during the previous frame.
Percent of total life used (from 0 to 1).
Expected lifetime of particle.
|MAPU MAPV MAPW|
Point or vertex texture coordinates.
Total number of points.
Total number of points in source group.
|NX NY NZ|
The point number of the currently processed point. The
|RESTX RESTY RESTZ|
The rest position.
The sliding state of the particle.
Elasticity of a point.
Point is stopped.
1 if particle is stuck to a collision object.
|TX TY TZ|
Surface UV values.
|VX VY VZ|
Point spline weight.
Distance from particle to last collision.
|HCR HCG HCB|
Diffuse color at the collision point on the surface the particle collided with.
ID for last collision. You can control how this attribute is set in the Collision or Limit POP to help distinguish types of collisions.
The time at which the last collision occurred.
The texture map UV coordinates for the surface location where the last collision occurred.
|HNX HNY HNZ|
The normal at the surface location where the last collision occurred.
|HTX HTY HTZ|
World space position of the last collision.
The UV coordinates for the surface location where the last collision occurred.
Number of times the particle has collided.
Added by Color POP
Point or vertex alpha value.
|CR CG CB|
Diffuse point or vertex color.
Added by Property POP
Charge of the particle.
Point is clinging to geometry.
Leader to follow.
|SCALEX SCALEY SCALEZ|
Added by Proximity POP
Either the point number or id of the particle nearest to this one.
The distance to the nearest particle.
The number of particles within a specified proximity to this particle.
Added by Rotation POP
|ROTX ROTY ROTZ|
Added by Source POP
ID number, which always remains constant.
Original Source point was birthed from.
Parent’s ID Number.
Added by Speed Limit POP
Added by Sprite POP
Sprite rotation around view axis (in degrees).
Texture coordinate of sprite’s lower-left corner.
Size of sprite in texture space.
Controlled by Suppress Rule POP
Suppress default position rule.
Suppress default velocity rule.
Suppress default up-vector rule.
Suppress default aging rule.
1 if particle is suppressing its default rotation rule.
1 if particle is suppressing its default angular velocity rule.
Added by Up Vector POP
|PVX PVY PVZ|
|UPX UPY UPZ|
Absolute speed of particle.
|AttractToCurvePoints||Load | Launch|
This example demonstrates how points can be used as attractors.
By creating a curve containing points, and using a Point SOP, force attributes are given to the curve points. These attributes allow the Attractor POP to use the point forces which in turn act upon the particles.
In this case, an effect is created in which the particles “march” along the curve.
|AttractToGrid||Load | Launch|
This file applies a radial force to a grid, and uses an Attractor POP to force the particles to be attracted to that grid.
The Kill POP kills particles once they pass a certain threshold.
|AttractToRing||Load | Launch|
This example shows just one way of creating and using an attractor object to pull particles from an emitter and have them stop when the particles reach the attractor.
The techninque of birthing a fixed number of points but have them stream from their birthed position while still retaining their initial velocity and position using a Group POP and a Suppress Rule POP is necessary when you want to retain point counts over all the frames for blending purposes, when using the Softbody POP or any other reason where you don’t want the particle count to change
The importance of drag when using attractors. The mass of the particles and their current drag can make or break your simulation.
How to put some nice turbulence in your particle system by using a Force POP and absolutely no direct forces but just using its noise.
|Chaser||Load | Launch|
The Attractor POP has the Attractor Use set to Single point per particle. As the sphere is animated in the object editor, the particles try to keep up.
Examples that use this node
|Example for||Example name|
|Particle Fluid Object||PopFlow||Load | Launch|
|Particle Fluid Solver||PopFlow||Load | Launch|
|Stream||SparksStream||Load | Launch|