Emitter HUD Parameters
The HUD contains the most frequently used emitter controls necessary to modify a particle
system’s size and shape. These parameters are a subset of those found in the Emitter
Inspector. In 2D projects, the Emitter HUD contains a group of sliders and the emission
control, which provides a visual way to manipulate three particle system parameters:
Emission Range, Emission Angle, and Speed.
Emission range
Emission angle (angle of
arrow) and speed (length
of arrows)
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When 3D is enabled in the Emitter Inspector, the Emitter HUD offers additional 3D controls.
In 3D, the emission control modifies the Emission Latitude and Emission Longitude
parameters.
Emission control
(pointed and
spread upward)
When an emitter and the 3D Transform tool (in the toolbar) are selected, the 3D Emitter
HUD expands to display additional controls that allow you to transform the emitter in X,
Y, and Z space, regardless of whether the group containing the emitter is 2D or 3D.
For more information on using the 3D transform controls in the HUD, see
3D Transform
Tools
.
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For particle systems containing multiple cells, the Emitter HUD parameters simultaneously
modify the effect of each cell’s parameters relative to one another. This means that for a
particle system consisting of two cells with different scale values, changing the scale in
the HUD resizes both cells simultaneously. For example, increasing the scale in the HUD
by 200% does not change the scale of both cells to 200%, but resizes the cells relative to
their original scale values.
Original particle system
Particle system scaled to 200 percent
For this reason, in emitters with multiple cells, the HUD parameters are displayed as
percentages. When you modify the parameters of a single cell, the cell parameters are
adjusted directly.
Birth Rate:
A slider that defines how many particles are created every second.
Life:
A slider that defines how long each particle remains onscreen (in seconds) before
disappearing from existence.
Scale:
A slider that defines the size of each particle, relative to the original size of the cell.
Emission Range:
A slider that defines the angle at which particles are emitted.
Emission Control:
A graphical control that lets you modify several parameters
simultaneously, described below:
• Emission Range (2D only): Drag the two points on the outer ring of the graphical emission
control to define the range of degrees at which particles are generated. In other words,
the Emission Range parameter defines the size of the “slice” of the pie graph that the
particles fill when generated. This graphical control adjusts the same parameter as the
Emission Range slider.
• Emission Angle (2D only): Drag the blue arrows clockwise or counterclockwise to change
the direction in which particles are emitted (within the angle defined by the Emission
Range control).
• Emission Speed (2D only): Drag the blue arrows outward or inward to define how quickly
particles move away from the emitter.
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Use the following modifier keys to more precisely manipulate the graphical emission
control in the HUD:
• Shift (while adjusting Emission Angle): Restricts angles to 45 degree increments.
• Shift (while adjusting Emission Range): When working with a 2D emitter, restricts to
22.5-degree increments.
• Command: When working with a 2D emitter, adjusts Emission Angle only.
• Option: When working with a 2D emitter, adjusts Emission Speed only.
Emission Latitude/Emission Longitude Control (3D only):
When using a 3D particle
emitter (when the 3D checkbox is selected in the Emitter Inspector), the emission control
of the HUD lets you modify the Emission Latitude and Emission Longitude parameters.
Drag the sphere in the center of the circle to modify the emission direction (in degrees
latitude and longitude) of the particles. You can also enter specific values in the Emitter
Inspector.
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Drag the Emission Range slider (above the sphere) to define the range of degrees at
which particles are generated. In other words, this control defines the size of the cone
that the particles fill when generated in 3D space.