After Effects – Reverse the layer order and other great layer tools

This confounded me for a while, until someone mentioned the solution–which was embarassingly easy.

To reverse the order of your layers in your timeline, simply shift-select your desired layers starting at the bottom to the top. Cut them (CMD-X). Paste them back in. (CMD-V)

Done. The layers are in reversed order because After Effects stacks the layers in the order you select them. You can even select them in any arbitrary order then cut and re-paste them if you need to re-stack them.

Other handy layer-ordering tools:

Randomize layer order:  LayerRandomShifter.jsx

Shift, sequence, and stagger layers: Rift

Things to know when creating Adobe Illustrator artwork for After Effects.

Color and Effects:
– RGB mode will keep your colors more accurate.
– Transfer control settings don’t import to After Effects. If you’re using it to create new color, apply “Flatten Transparency” to your objects. Also see use of transparency below.
– Use transparency only to create transparent elements, not lighter colors. When they get animated in front of another object, we’ll naturally see the background object through them. (If the transparency needs to animate, keep it at 100% opacity and include a note in the script.)
– Effects, Rasterization, etc. It’s often better to just show the animator a sample and let them integrate it in AE using AE’s tools. It’s also optionally helpful to designate the transfer control in the layer name (e.g. layer name: “MULTIPLY-bird on wire”)

Artwork and Artboards:
– It works well to use an over-sized Artboard with a 1920×1080 square as a layout guide to avoid having your art cropped at the edges. Art that extends beyond your Artboard will be cropped on import, making them less able to be animated.
– After Effects will only import one of your Artboards. If you’ve created the entire project of multiple artboards in one AI document, it works well to export your individual Artboards (Export…”use artboards” checked).
– Related to the previous, one scene per AI document is safer and easier when something gets changed by the client.  Building the entire sequence in one document over multiple Artboards is convenient for illustration, but it will be broken into one Artboard per .ai file before it goes into AE, so you you might as well do it on your end before sending it on. Then, if you have a change, you’re only changing one scene without requiring re-breakup of Artboards.

Text:
– Custom text that won’t be changing may fare better if you use “Outline Font” so there are no font issues.

Layers:
– After Effects only extracts layers, not sub-layers. That means each logical element that might get animated independently should be on it’s own layer.
– Groups are great! The layer is king in AE, but if you’ve logically grouped your elements, it’s much easier for an animator to go back and work with your art when a layer needs to be split up.
– You named your layers? Bless you.

(These notes relate to CS6)

James Merry also has some great tips (and pictures!) on this process

After Effects Expression – Oscillate Layer in Ellipse

This makes a layer move in an ellipse around it's position. 
Putting zero for either value creates a simple Sine oscillation. 
(left/right or up/down)
-----paste below code into Position expression-----
//--OSCILLATE LAYER IN AN ELLIPSE--//

//USER ADJUSTED:
radiusDistX = 30;  //set to zero for up/down oscillation
radiusDistY = 100;  //set to zero for sideways oscillation
period = 1; 
// DON'T ADJUST
value + [Math.sin(time*period)*radiusDistX,
-Math.cos(time*period)*radiusDistY]

-----------------end code-------------------------

After Effects Expression – Make an object bounce

//MAKE A LAYER BOUNCE
bounceSpeed=7;
 flight=01;
 bounceHeight=3.5;
t=Math.abs((time*2*bounceSpeed)%2-1);
 t=linear(t,flight,0,0,1);
 b=Math.cos(t*Math.PI/2);
value - [0,bounceHeight*b];