Controlling parameters with null or expressions?

[Kevin Camp]

yes, you can link any of the parameters of an effect to a single effect. that effect could be on a null or one of the effects that is already applied (i find it easier to keep track of if i use a null).

each stroke effect will need to be linked to the ‘control’ stroke effect. you can do this either by enabling enabling expressions for a particular parameter (you mentioned color) and then pick whipping it to the ‘control’ parameter. and then copy and paste the expression into the expression fields for each stroke effect. or you could save an animation preset for the stroke effect (after adding the expression), then remove the stroke effect from each layer, select all layers and apply the preset (if you only have a single effect on each layer you can remove a all effects from selected layers from effect>remove all effects).

once linked to the ‘control’ effect null, when you make a change to the color, it will change all of them.

Kevin Camp
Designer – KCPQ, KMYQ & KRCW

[Kevin Camp]

one note, if making an animation preset…

when saving the effect preset, select the layer that you linked to the ‘control’ effect and hit ‘uu’ (that’s 2 u’s). this will reveal all the parameters that have been changed from the defaults. you will want to select each of those before saving the preset (animation>save animation preset), that way all you effect settings will be the same.

now if the settings are not all the same for each stroke effect, the copy/paste method may be better…

Kevin Camp
Designer – KCPQ, KMYQ & KRCW

[Kim Petersen]

Thanks a lot Kevin! You just saved me a lot of precious time 🙂

[Darby Edelen]

[moldyboot] “and then copy and paste the expression into the expression fields for each stroke effect.”

There is an option under the Edit menu in After Effects to “Copy Expression Only.” If you select the property that the expression is applied to, and use the “Copy Expression Only” command you can then Paste the expression to all of your layers at once by selecting them and pressing cmd+V (ctrl+V on PC) as you usually would.

If the property exists on those layers then the expression will be applied to the correct property automatically (if it doesn’t… well, I don’t know what happens then). So just make sure you have the effect applied to all of your layers, set the expression up once, copy the expression only, select all of the layers you need it applied to and paste.

Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA

[Kevin Camp]

[Darby Edelen] “There is an option under the Edit menu in After Effects to “Copy Expression Only.” If you select the property that the expression is applied to, and use the “Copy Expression Only” command you can then Paste the expression to all of your layers at once by selecting them and pressing cmd+V (ctrl+V on PC) as you usually would. “

thanks darby, that’s a welcome addition to my daily workflow….

Kevin Camp
Designer – KCPQ, KMYQ & KRCW

[Aharon Rabinowitz]

If you haven’t explored the expression controller effects, they are very powerful. They allow you to use a Null object or other layer as a control panel for other layers. You can find them under Effects > Expression Controls

Watch these videos for more info:

Expression Controls Pt 1

Expression Controls Pt 2

Expression Controls Pt 3

Aharon Rabinowitz
Email: arabinowitz (AT) yahoo (DOT) com
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