Adobe AFTER EFFECTS CS3 PROFESSIONAL User Manual page 443

Specifies the opacity of the midpoint of the stroke. This control works in terms of relative opacity,
Mid-point Opacity
not absolute opacity. Setting it to 0 makes the change in opacity smooth from the start point to the end point, as if
there were no midpoint at all.
Specifies the location of the midpoint within a segment: Lower values move the midpoint closer
Mid-point Position
to the beginning; higher values move the midpoint closer to the end. Use this control to move the midpoint opacity
from the center of the stroke.
See also
"About randomness and random seeds" on page 352
Write-on effect
The Write-on effect animates strokes on a layer. For example, you can simulate the action of hand-writing of cursive
text or signatures.
Note: A convenient way to animate Brush Position is to use Motion Sketch to create Position keyframes on a new solid
layer and then use an expression on the Brush Position property to link it to the Position property on the new solid layer.
(See "Sketch a motion path with Motion Sketch" on page 201 and "Add, edit, and remove expressions" on page 545.)
This effect works with 8-bpc color.
Other methods of animating paint strokes and text are also available. For example, you can animate text by using the
type tools and text animators, and you can animate a paint stroke applied with a paint tool. Paint strokes can have a
Write-on Duration setting, which you can use to create similar results as with the Write-on effect. You can also
animate shape paths for a similar result with the Trim Paths operation. (See "Animating text" on page 284, "Animate
paint strokes" on page 309, and "Managing and editing shapes" on page 324.)
The position of the brush. Animate this property to create a stroke.
Brush Position
The duration, in seconds, of each brush mark. If this value is 0, the brush mark has unlimited
Stroke Length (secs)
duration. Use a single, constant, nonzero value to create a snakelike movement of the stroke. Animate this value to
make the stroke expand and contract.
The time interval, in seconds, between brush marks. Smaller values produce smoother paint
Brush Spacing (secs)
strokes but take more time to render.
Paint Time Properties and Brush Time Properties
applied to each brush mark or to the entire stroke. Choose None to apply values at each time to all brush marks in
the stroke. Choose a property name for each brush mark to retain the value for that property at the time that the
brush mark was drawn. For example, if you choose Color, then each brush mark keeps the color specified by the
Color value at the time that the mark was drawn.
How the paint stroke interacts with the original image:
Paint Style
•
Paint stroke appears over original image.
On Original Image
•
Paint stroke appears over transparency; the original image doesn't appear.
On Transparent
•
The original image is revealed by the paint stroke.
Reveal Original Image
Specifies whether paint properties and brush properties are
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