Force particle node

Applies a global directional force, such as gravity.

All

Parameters

Local variables

An increase in mass impedes acceleration for a given constant force.

Drag is a force opposing the direction of motion. Drag is velocity sensitive: the larger the velocity, the greater the effect of drag. It’s useful for limiting the velocity of particles.

Tip

Use the Property POP to set “physical” attributes of particles such as mass and drag.

This operator modifies the following attributes: accel.

See the Wind POP for different kind of directional force you can apply separately or in combination with this operator.

Using Force

Select the particle system you want to apply force to.
Click the Force tool on the Drive Particles tab.
Specify the node settings in the operation controls toolbar or parameter editor.

You must specify the amount of force and direction of force in the operation controls toolbar or parameter editor.

Using Gravity

Select the particle system you want to apply gravity to.
Click the Gravity tool on the Drive Particles tab.
Specify the node settings in the operation controls toolbar or parameter editor.

Using Noise

Select the particle system to add noise to.
Click the Noise tool on the Drive Particles tab.
Specify the node settings in the operation controls toolbar or parameter editor.

Parameters

Activation	Turns this node on and off. The operator is only active if this value is greater than 0. This is useful to control the effect of this node with an expression.
Source Group	Only affect a group of points (created with, for example, a Group POP or Collision POP) out of all the points in the input.

Force

Reference Object	Path of an object from whose transform to extract the force direction. Overrides the Force parameter below.
Force	Strength of the force along each axis.
Scale	Scaling factor for the force.
Ignore Mass	Ignores any mass attributes on the input particles.
Override Mass	Replaces any mass attributes on the input particles with the value of the Mass parameter below.
Mass	Mass to use when Override mass is on.

Noise

The parameters on this tab add randomness to the force. This makes particles more or less affected at random, creating a less uniform effect.

Seed

Seed value for the random turbulence generator.

Turbulence

Number of iterations of fractal noise to add.

Roughness

Scale of noise added with each iteration.

Exponent

Noise attenuation exponent.

Frequency

Spatial frequency of noise field in X, Y, and Z.

Amplitude

Maximum value of noise field.

Offset

Amount to shift noise along X, Y, and Z axes.

Noise Type

Method used to generate noise. Hermite Interpolation and Improved Hermite are fastest.

Hermite Interpolation	Uses splines to interpolate values in the noise field.
Sparse Convolution	More computationally expensive, but produces noise fields free of artifacts present in the Hermite methods.
Improved Hermite	Uses a more linear interpolation than Hermite interpolation.
Alligator Noise	Provides a very different look than the other noise types.

Local variables

Standard POP local variables

AGE	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.
DEAD	Point is dead.
ITER	Processing iteration number.
JUSTHIT	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.
LIFE	Percent of total life used (from 0 to 1).
LIFESPAN	Expected lifetime of particle.
MAPU MAPV MAPW	Point or vertex texture coordinates.
NPT	Total number of points.
NGRP	Total number of points in source group.
NX NY NZ	Normal vector.
PT	The point number of the currently processed point. The `PT` is not constant like `ID`; it changes based on the number of points.
RESTX RESTY RESTZ	The rest position.
SLIDING	The sliding state of the particle.
SPRINGK	Elasticity of a point.
STOPPED	Point is stopped.
STUCK	1 if particle is stuck to a collision object.
TENSION	Spring tension.
TIMEINC	Time increment.
TX TY TZ	Point position.
U V	Surface UV values.
VX VY VZ	Velocity direction.
WEIGHT	Point spline weight.

Added by Collision POP/Limit POP

DIST	Distance from particle to last collision.
HCR HCG HCB	Diffuse color at the collision point on the surface the particle collided with.
HITID	ID for last collision. You can control how this attribute is set in the Collision or Limit POP to help distinguish types of collisions.
HITTIME	The time at which the last collision occurred.
HMAPU HMAPV	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.
HU HV	The UV coordinates for the surface location where the last collision occurred.
NUMHIT	Number of times the particle has collided.

Added by Color POP

CA	Point or vertex alpha value.
CR CG CB	Diffuse point or vertex color.

Added by Property POP

ATTRACT	Attractor point.
CHARGE	Charge of the particle.
CLING	Point is clinging to geometry.
DRAG	Point drag.
FOLLOW	Leader to follow.
MASS	Point mass.
PSCALE	Particle Scale.
SCALEX SCALEY SCALEZ	Non-uniform scale.

Added by Proximity POP

NEAREST	Either the point number or id of the particle nearest to this one.
NEARESTDIST	The distance to the nearest particle.
NUMPROXIMITY	The number of particles within a specified proximity to this particle.

Added by Rotation POP

ROTA	Rotation angle.
ROTX ROTY ROTZ	Rotation axis.

Added by Source POP

GEN	Generation.
ID	ID number, which always remains constant.
ORIGIN	Original Source point was birthed from.
PARENT	Parent’s ID Number.

Added by Speed Limit POP

SPEEDMAX	Maximum speed.
SPEEDMIN	Minimum speed.

Added by Sprite POP

SROT	Sprite rotation around view axis (in degrees).
STEXU STEXV	Texture coordinate of sprite’s lower-left corner.
STEXW STEXH	Size of sprite in texture space.
SX SY	Sprite scale.

Controlled by Suppress Rule POP

SUPPPOS	Suppress default position rule.
SUPPVEL	Suppress default velocity rule.
SUPPUP	Suppress default up-vector rule.
SUPPAGE	Suppress default aging rule.
SUPPROT	1 if particle is suppressing its default rotation rule.
SUPPANGVEL	1 if particle is suppressing its default angular velocity rule.

Added by Up Vector POP

PVX PVY PVZ	Previous velocity.
UPX UPY UPZ	Up vector.

Added by Location, Source, Softbody, Split POPs

SPEED

Absolute speed of particle.

Usages in other examples

Example name	Example for
popswithrbdcollision	RBD Point Object dynamics node	Load \| Launch
Meteor	Collision particle node	Load \| Launch
BirthRing	Collision particle node	Load \| Launch
Deforming	Collision particle node	Load \| Launch
BounceSplit	Collision particle node	Load \| Launch
FollowInteract	Follow particle node	Load \| Launch
AttractToRing	Attractor particle node	Load \| Launch
Splatter	Event particle node	Load \| Launch
FireworksSetup	Split particle node	Load \| Launch
SoftBodySheet	Soft Body particle node	Load \| Launch