You are here: Reference Guide > Particles Nodes > ParticleDrag

ParticleDrag

With ParticleDrag, you can apply drag on your particles to gradually alter their velocity over time. This means particles will start off fast and gradually slow down, unless you use negative values to apply the reverse effect.

The formula is: particle velocity*(1-drag). If the drag value is 0.01, the particles lose 1% of their velocity per frame.

Inputs and Controls

Connection Type	Connection Name	Function
Input	particles	The particle system to which you intend to apply drag.

Control (UI)	Knob (Scripting)	Default Value	Function
ParticleDrag Tab
display	display	unchanged	Adjust the display characteristics of the particles. These settings don’t affect the render output of the scene; these are for display purposes only in the 3D Viewer. • off - hides the particles. • wireframe - displays only the outlines of the particle. • solid - displays all particles with a solid color. • solid+wireframe - displays the particles as solid color with the particles outlines. • textured - displays only the surface texture. • textured+wireframe - displays the wireframe plus the surface texture. • unchanged - doesn't change the particles display mode. The Viewer can override this setting.
selectable	selectable	enabled	When enabled, you can select the particles in the Viewer by clicking on them.
render	render_mode	unchanged	Sets how the particles will render. This control is independent from the display selection, but has the same settings.
drag	drag	0	Sets the proportion of each particle's velocity that is lost per frame, where 0.01 = 1 percent and 1 = 100 percent. NOTE: Negative drag values increase the particle velocity.
rotational drag	rotational_drag	0	Sets the proportion of each particle's rotation that is lost per frame, where 0.01 = 1 percent and 1 = 100 percent. NOTE: Negative values increase the particle rotation velocity.
Conditions Tab
probability	probability	1	Sets the probability that this node affects your particles. If you set this to zero, the node won’t affect any particles, and if the value is 1, the node will affect every particle.
min age	min_age	0	Limits the effect of this node to particles above this minimum age. The age of the particle is its lifetime normalized between 0 and 1.
max age	max_age	1	Limits the effect of this node to particles below this maximum age. The age of the particle is its lifetime normalized between 0 and 1.
random seed	seed	0	Sets the integer to change the results of generated randomness in your particles. You can achieve slightly different effects by changing this number.
channels	channels	all	Specifies which particle channels the effect of this node should be applied to. Channels a and b are arbitrary names for channels which are useful if you want different ParticleEmitter nodes or other particle force nodes to have an effect on separate channels.
Region Tab
region	region	none	Sets the region which you want to use to confine the particle effect to. For example, if you choose a sphere, only particles inside that sphere shaped region will be affected by particle effects. • none - all particles are affected as normal. • sphere, box, half-space, and cylinder - controls the region’s boundary shape.
invert region	region_invert	disabled	When enabled, particles outside the region are affected rather than those inside it.
	file_menu	N/A	Select to import or export a channel file: • Import chan file - import a channel file and transform the region marker according to the transformation data in the channel file. Channel files contain a set of Cartesian coordinates for every frame of animation in a given shot. You can create and export them using Nuke or 3D tracking software, such as 3D-Equalizer, Maya, or Boujou. • Export chan file - export the translation parameters that you’ve applied to the region marker as a channel file. This is a useful method of sharing setups between artists.
	snap_menu	N/A	• Match selection position - the region marker is snapped to a new position depending on the points selected. • Match selection position, orientation - the region marker is snapped to a new position and orientation depending on the points selected. • Match selection position, orientation, size - the region marker is snapped to a new position, orientation, and size depending on the points selected.
transform order	xform_order	SRT	Sets the operation order for scale (S), rotation (R), and translation (T). The possible operation combinations are SRT, STR, RST, RTS, TSR, TRS.
rotation order	rot_order	ZXY	Sets the order of rotation. The possible axial combinations are ZXY, XYZ, XZY, YXZ, YZX, ZXY, ZYX.
translate	translate	0, 0, 0	Lets you translate the region marker along the x, y, and z axes. you can also adjust translate values by clicking and dragging the axis in the 3D Viewer.
rotate	rotate	0, 0, 0	Lets you rotate the region marker around the x, y, and z axes. You can adjust rotate values by holding down Ctrl/Cmd and dragging in the 3D Viewer.
scale	scaling	1, 1, 1	Lets you scale the region marker on the x, y, and z axes.
uniform scale	uniform_scale	1	Lets you scale the region marker simultaneously on the x, y, and z axes.
skew	skew	0, 0, 0	Lets you skew the region marker on the x, y, and z axes.
pivot	pivot	0, 0, 0	When you make changes to the region marker’s position, scaling, skewing, and rotation, these occur from the location of the object’s origin point or pivot. The pivot x, y, and z controls allow you to offset the pivot point and move it anywhere you like - you can even move it outside of the object. Subsequent transformations applied will then occur relative to the new pivot point location. You can also hold down Ctrl/Cmd+Alt and drag the pivot point to a new location in the 3D Viewer.
Local Matrix
specify matrix	useMatrix	N/A	Enable this control to specify matrix values for the object you’re transforming as an alternative to setting transform, scale, skew and pivot values above.
matrix	matrix	N/A	The matrix displays values from the object’s transform, rotate, scale, skew, and pivot controls. Check specify matrix and copy or drag-and-drop matrix values from another object to apply those values, for example, if you wanted to align objects in a scene.