Apple Motion 2 - Manual (Page 596)

596 Chapter 8 Working With Particles
Number of Arms (Burst or Spiral): Defines the number of branches from which
particles are emitted. The default value is 3.
Twists (Spiral): Defines the number of turns in the spiral. The default value is 0.25.
Amplitude (Wave): Defines half the distance from the highest point to the lowest
point in the wave. Higher values result in more extreme waves.
Start Point (Line, Wave): Two sliders that define, in X and Y coordinates, the first point
of the line used as the emitter shape.
End Point (Line, Wave): Two sliders that define, in X and Y coordinates, the second
point of the line used as the emitter shape.
Shape Source (Geometry): An object that defines the shape of the emitter. Spline
objects may be dropped onto this control to assign the desired shape.
Image Source (Image): An object that specifies the image used to define the shape of
the emitter. Any image or movie clip can be dropped onto this control to assign the
desired shape.
Emission Alpha Cutoff (Image): When the Image Source object contains an alpha
channel, this slider defines the minimum opacity value that is necessary to create
particles at that point on the source image. For example, when set to 25 percent,
particles appear only where the alpha value of the image is equal to or greater than 25
percent opacity. The lower the Emission Alpha Cutoff value, the more particles appear.
In order for this parameter to be effective, the alpha channel needs to have areas of
varying transparency.
Emission Angle (all shapes): A dial that sets the direction in which particles travel. This
parameter works in conjunction with the Emission Range parameter. It is equivalent to
one of the functions of the graphical Emission control in the Dashboard. This parameter
is unique to the emitter object.
Spiral emitter Shape set to default Number of
Arms and Twists. Spiral emitter Shape with Twists set to .70.
01112.book Page 596 Sunday, March 13, 2005 10:36 PM