You can link the Slider Control expression control to properties in After Effects to create a gui slider interface with a key-able value. An easy way to do this is to do the following.
- Make a null layer. Apply the Slider Control expression control effect to the null layer.
- Create an expression by option/alt clicking on the “stopwatch” of the property.
- Use the pick whip to connect the property to the Slider Control.
You can also link individual values of properties, the x position for example, to the slider if you highlight that value and then connect via the pick whip. You must be able to access the individual arrayed values of the property, so write your expression as below, for example:
Highlight the value “position” then use the pick whip to connect to the Slide Control. You will get this new expression as a result (if your null is named controllerNull):
[position,thisComp.layer("controllerNull"). effect("Slider Control")("Slider")]
The following expression is used to link a series layers to the slider. The “index” value is used to echo the layer number, here the z position of a 3d layer. The slider control is used as a multiplier on that value. The result is an accordion like effect.
[position,position, index*thisComp.layer("controllerNull").effect("Slider Control")("Slider")]