Adobe AFTER EFFECTS 7.0 - Changing the rendering order; To make a movie from a composition

ADOBE AFTER EFFECTS 7.0
User Guide
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5 Drag the pick whip to the hour hand’s Rotation property. The following expression appears:
thisComp.layer("hour hand").rotation
6 Tomaketheminutehandrotate12timesasfastasthehourhand,add*12 attheendoftheexpressionasfollows:
thisComp.layer("hour hand").rotation*12
Example: To increase blur with depth
The following example shows how to use the pick whip to control blur by a layer’s position in z-space. This expression
is useful for making an object blurrier as it travels farther away in space.
1 Import or create a layer in the shape of a star. (See “About layers” on page 149.)
2 Click the 3D switch for the layer and set Position keyframes so that it moves farther away in z-space. (See “To
designate a layer as 3D” on page 175 and “Using keyframes” on page 192.)
3 Apply the Fast Blur effect. (See “Applying and controlling effects” on page 348.)
4 Select the Fast Blur effect’s Blurriness property in the Timeline panel and choose Animation > Add Expression.
5 Drag the pick whip to the Position property. The following expression appears:
position[2]
6 If the blur is too intense, cut the blur amount by one-fifth by adding /5 to the end of the expression as follows:
position[2]/5
Manually entered expression examples
Example: To position one layer between two others
This example expression positions and maintains one layer at a balanced distance between two other layers. To
achieve this effect, you need three layers in your composition.
1 Start with three layers. (See “About layers” on page 149.)
2 Create motion paths for the first two layers in the Timeline panel. (See “To create a motion path” on page 210.)
3 Select the Position property for the third layer and choose Animation > Add Expression.
4 Select the default expression text and type the following:
(thisComp.layer(1).position + thisComp.layer(2).position)*.5
Example: To create a trail of images
This example expression instructs a layer to be at the same position as the next higher layer in the Timeline panel,
but delayed by a specified amount of time (in this case, 0.5 seconds). You can set similar expressions for the other
geometric properties. This expression requires two or more layers.
1 Start with two solids that are scaled to approximately 30%. (See “To create a solid-color layer” on page 150.)
2 Create a motion path for the first layer. (See “To create a motion path” on page 210.)
3 Select the Position property for the second layer and choose Animation > Add Expression.
4 Select the default expression text and type:
thisComp.layer(thisLayer, -1).position.valueAtTime(time - .5)