Marching ants

The marching ants effect is an animation technique often found in selection tools of computer graphics programs.

Popular graphics programs, such as the GIMP and Adobe Photoshop, implement their selection tools using the marching ants effect.

The method has the disadvantage of not looking like marching ants with selection borders that are not parallel to the coordinate axes.

With the selection problem in mind, Bill Atkinson went to his favorite pub in Los Gatos.

He implemented the idea and showed it to Rod Perkins from the Lisa team, who told Bill the effect reminded him of "marching ants".

An example of a rectangle using marching ants
Eight pixel patterns that can be used to produce marching ants