SPH Density Test particle node

Kills particles if the surrounding region exceeds a certain density.

All

Parameters

Inputs

Local variables

See also: Particle Fluid Emitter, Gas SPH Density

This object uses the mass, density and restdensity point attributes of its inputs. For each point in the source group, the POP computes the density of the particle field in the surrounding region (that is, the field not including the source group). If the density exceeds a certain threshold dependent on the particle’s rest density, then the particle is killed.

Currently, this operator is used to control the output of the Particle Fluid Emitter DOP.

Parameters

SPH Density Test

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.
Group	Killed particles are inserted in to the group specified here.
Density Threshold Multiplier	This parameter controls the density at which particles will be killed. For example, if the Density Threshold Multiplier is set to 2.0, then particles will be killed if the density of the field surrounding them exceeds 2.0 times the rest density of the particles.
Override Rest Density	When this is enabled, the Rest Density parameter, rather than the restdensity point attribute, is used to determine the rest density of each particle.
Rest Density	When Override Rest Density is enabled, this parameter is used as the rest density of the particle field.

Inputs

Input 1

The particles to test.

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
DrainExample	Particle Fluid Sink dynamics node	Load \| Launch
VolumeSource	Particle Fluid Emitter dynamics node	Load \| Launch
DrainExample	Particle Fluid Emitter dynamics node	Load \| Launch
PressureExample	Particle Fluid Object dynamics node	Load \| Launch
PressureExample	Particle Fluid Solver dynamics node	Load \| Launch