Apple Motion 5.1.1 - Manual (Page 532)

Chapter 14 Particles 532
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Arrangement: This pop-up menu, available when Rectangle, Circle, Image, Box, or Sphere
is chosen in the Shape pop-up menu, specifies the pattern from which the particles are
generated. The arrangement options are:
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Outline: Emits particles along the edge of the shape in 2D emitters and along the surface of
the shape in 3D emitters.
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Tile Fill: Emits particles from a tiled pattern of rows, columns, and ranks (for 3D emitters) in
the circle, rectangle, image, box, or sphere. You can specify the number of columns, rows, and
ranks, as well as the Tile Offset.
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Random Fill: Emits particles randomly from within the circle, rectangle, image, box, or sphere.
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Size: This slider becomes available when Rectangle or Box is chosen in the Shape pop-up
menu. Defines the size of the rectangle or cube from which particles are emitted. The Size
slider is available whether the Arrangement is set to Outline, Tile Fill, or Random Fill. When
Rectangle is the selected shape, the Width and Height parameters become available. When
Box is selected, an additional Depth parameter is available.
Note: The Height is measured in project pixels; however, the Width is measured in square
pixels. This is done so a shape that is numerically square will look square when Correct for
Aspect Ratio is turned on (checkmarked) in the View pop-up menu in the top-right corner of
the Canvas.
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Columns: This slider becomes available when one of the following is chosen in the Shape
pop-up menu: Rectangle, Circle, Image, Box, or Sphere; in addition, Arrangement must be set
to Tile Fill. This parameter specifies the number of horizontal emitter points on a grid over the
selected emitter shape. In the case of an irregular shape (nonrectangular), grid points that fall
outside of the shape are ignored.
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Rows: This slider becomes available when one of the following is chosen in the Shape pop-up
menu: Rectangle, Circle, Image, Box, or Sphere; in addition, Arrangement must be set to Tile
Fill. This parameter specifies the number of vertical emitter points on a grid over the selected
emitter shape. In the case of an irregular shape (nonrectangular), grid points that fall outside
of the shape are ignored.
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Ranks: This slider becomes available when Box or Sphere is chosen in the Shape pop-up menu
and Tile Fill is the selected Arrangement. This parameter specifies the number of points in Z
space on a grid over the selected shape from which particles are emitted.
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Tile Offset: This slider becomes available when one of the following is chosen in the Shape
pop-up menu: Rectangle, Circle, Image, Box, or Sphere; in addition, Arrangement must be set
to Tile Fill. Values from 0 to 100% offset the rows toward the right, and values from 0 to –100%
offset the rows toward the left. A value of 50 or –50% creates a “brickwork” pattern.
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Image Source: This image well, available when Image is chosen in the Shape pop-up menu, lets
you specify the object used to define the shape of the emitter.
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Shape Source: This image well, available when Shape is set to Geometry, lets you specify a
spline object to define the shape of the emitter.
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Emission Alpha Cutoff: This slider becomes available when Image is chosen in the Shape
pop-up menu. When the Image Source object contains an alpha channel, this slider defines
the minimum opacity value necessary to create particles at that point on the source image.
For example, when set to 25%, particles appear only where the alpha value of the image is
equal to or greater than 25% opacity. The lower the Emission Alpha Cutoff value, the more
particles appear. For this parameter to be effective, the alpha channel must have areas of
varying transparency.
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