Drag
particle node
Applies drag to the velocity of particles.
This operator applies drag against a particle’s velocity. The resistance is proportional to the particle’s speed and the value of its drag attribute, which represents the particles drag coefficient, or how “unaerodynamic” the particle is.
For particles born with some velocity (such as from a Location POP), in the absence of other forces, end of lifespan, etc., the particle will basically maintain the same velocity forever. Drag acts like wind resistance or friction in the real world, slowing down particles over time until they eventually stop.
You can apply drag to the linear velocity and/or the angular velocity of the input particles.
This operator modifies the following attributes: accel.
Using Drag
-
Select the
particle system you want to apply drag to. -
Click the
Drag 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 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. |
|
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. |
|
Apply to Linear Velocity |
Apply the drag to the linear velocity of the particles. |
|
Apply to Angular Velocity |
Apply the drag to the angular velocity of the particles. |
|
Scale |
Scaling factor for the effect of the drag. |
|
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. |
|
Override Drag |
Use the value of the Drag parameter below instead of any drag attributes on the input particles. |
|
Drag |
Drag to use when Override drag is on. |
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 |
|
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 | |
|---|---|---|
| CopyCubes |
Copy surface node |
|
| FollowStop |
Follow particle node |
|
| AttractToCurvePoints |
Attractor particle node |
|
| Chaser |
Attractor particle node |
|
| AttractToGrid |
Attractor particle node |
|
| AttractToRing |
Attractor particle node |
|
| SoftBodySheet |
Soft Body particle node |
|
| Disperse |
Interact particle node |
|
| SparksStream |
Stream particle node |
|
| PopFlow |
Particle Fluid Solver dynamics node |
|
| PopFlow |
Particle Fluid Object dynamics node |