06 · Masking

Masks, Mattes + Trim Paths

Oliver Aemisegger · 6 min read

Four ways to show and hide parts of a shape. Same ting, different tools.

This section enables you to

Masks

A mask cuts out part of a layer. You draw it directly on the selected layer.

01

Select the layer

Select the layer first. Otherwise you draw a new shape layer instead of a mask.
02

Draw the mask

Draw with the Pen tool or a shape tool on the selected layer.
G
03

Check it

Turn on the Solo switch to see only this layer.

A track matte uses another layer as the mask. The matte layer defines what’s visible.

01

Pick the matte

In the Track Matte column of your layer, choose the matte from the menu or drag the pick whip onto it.
02

Alpha or Luma

Alpha uses the shape of the matte, Luma uses its brightness. Invert flips it.

Linear Wipe is an effect that wipes a layer away in a straight line.

01

Apply the effect

Search for Linear Wipe in the Effects & Presets panel and drag it onto your layer.
02

Animate it

Animate Transition Completion from 0% to 100%.

Trim Paths draws and erases the stroke of a shape. Start and End set the length, Offset sets which part is shown.

Exercise

Same project, new comp in comps > maincomps

Expected result

01Create a comp motion_design_basics_06_masking and draw a filled circle.
02Duplicate it three times and place the four circles side by side.
03Circle 1: draw a mask that cuts it in half.
04Circle 2: draw a square above it, use it as Alpha Matte and animate the square across the circle.
05Circle 3: apply Linear Wipe and animate Transition Completion.
06Circle 4: turn the fill off and the stroke on, add Trim Paths and animate End.
07Preview and compare.

Action	Mac
Pen tool	`G`
Show Mask Path	`M`