The marching ants effect is an animation technique often found in

selection Selection may refer to: Science * Selection (biology), also called natural selection, selection in evolution ** Sex selection, in genetics ** Mate selection, in mating ** Sexual selection in humans, in human sexuality ** Human mating strat ...

tools of

computer graphics Computer graphics deals with generating images and art with the aid of computers. Computer graphics is a core technology in digital photography, film, video games, digital art, cell phone and computer displays, and many specialized applications. ...

programs. It helps the user to distinguish the selection border from the image background by animating the border. The border is a dotted or dashed line where the dashes seem to move slowly sideways and up and down. This creates an illusion of ''ants marching in line'' as the black and white parts of the line start to move. Some prefer the term marquee selection, as the effect resembles the chaser lights of a

marquee Marquee may refer to: * Marquee (overhang), a secondary covering attached to the exterior wall of a building * Marquee (structure), a structure placed over the entrance to a hotel, theater, casino, train station, or similar building. * Pole marquee ...

, and this term can be considered a synonym. Popular graphics programs, such as the

GIMP Gimp or GIMP may refer to: Clothing * Bondage suit, also called a gimp suit, a type of suit used in BDSM * Bondage mask, also called a gimp mask, often worn in conjunction with a gimp suit Embroidery and crafts * Gimp (thread), an ornamental tr ...

and

Adobe Photoshop Adobe Photoshop is a raster graphics editor developed and published by Adobe Inc., Adobe for Microsoft Windows, Windows and macOS. It was created in 1987 by Thomas Knoll, Thomas and John Knoll. It is the most used tool for professional digital ...

, implement their selection tools using the ''marching ants'' effect. The technique was first widely used by the

MacPaint MacPaint is a raster graphics editor developed by Apple Computer and released alongside the original Macintosh personal computer on January 24, 1984. It was sold bundled with its word processing counterpart, MacWrite, for US$195. MacPaint was n ...

program developed by

Bill Atkinson William Dana Atkinson (March 17, 1951 – June 5, 2025) was an American computer engineer, computer programmer, and photographer. Atkinson worked at Apple Computer from 1978 to 1990. Some of Atkinson's noteworthy contributions to the field of ...

. The easiest way to achieve this animation is by drawing the selection using a pen pattern that contains diagonal lines. If the selection outline is only one pixel thick, the slices out of the pattern will then look like a dashed line, and the animation can easily be achieved by simply shifting the pattern one pixel sideways and redrawing the outline. The method has the disadvantage of not looking like marching ants with selection borders that are not parallel to the coordinate axes.

Origin

Bill Atkinson, the creator of the effect, realized the effect while at a

pub A pub (short for public house) is in several countries a drinking establishment licensed to serve alcoholic drinks for consumption on the premises. The term first appeared in England in the late 17th century, to differentiate private ho ...

Los Gatos Los Gatos (; ; ) is an incorporated town in Santa Clara County, California, United States. The population is 33,529 according to the 2020 census. It is located in the San Francisco Bay Area just southwest of San Jose in the foothills of t ...

, California. An electric

Hamm's Beer Theodore Hamm's Brewing Company was an American brewing company established in 1865 in Saint Paul, Minnesota. Becoming the fifth largest brewery in the United States, Hamm's expanded with additional breweries that were acquired in other cities, ...

sign was on display at the pub. The sign consisted of an illuminated scene with an animated waterfall that featured water seeming to flow down into a lake. Bill figured that this effect could solve his problem due to its recognizability. He implemented the idea and showed it to Rod Perkins from the

Apple Lisa Lisa is a desktop computer developed by Apple, produced from January 19, 1983, to August 1, 1986, and succeeded by Macintosh. It is generally considered the first mass-market personal computer operable through a graphical user interface (GUI). I ...

team, who told Bill the effect reminded him of "marching ants".MacPaint Evolution
at folklore.org

References

External links

Fun with marching ants
describes another scheme for generating the marching ants pattern {{DEFAULTSORT:Marching Ants Graphical user interface elements History of computing