Creating Circular And Spiral Motion Paths

A simple expression, using a little bit of mathematics, that will let you create circular and spiral motion paths.

After Effects CS3
Useful things
Expressions

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The expression can be applied to anything in After Effects with a 'position' property to create a variety of effects. Here it's used with a light and Trapcode Particular.
For Circular:

radius=300
angle=time*200
x=radius*Math.cos(degreesToRadians(angle))
y=radius*Math.sin(degreesToRadians(angle))
z=0
centre=[640,360,0]
add(centre,[x,y,z])

For Spiral:

shrink=time+1
radius=1000/shrink
angle=time*200
x=radius*Math.cos(degreesToRadians(angle))
y=radius*Math.sin(degreesToRadians(angle))
//z=0 // no depth
z=time*time // with depth
centre=[640,360,0]
add(centre,[x,y,z])

by Ewan Smith

(Min. Version: After Effects CS3, Category: Useful things, Type: Expressions)

posted by Dan Johansson on Apr 12, 2010