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 strategie ...

tools of

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

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

GIMP GIMP ( ; GNU Image Manipulation Program) is a free and open-source raster graphics editor used for image manipulation (retouching) and image editing, free-form drawing, transcoding between different image file formats, and more specialized task ...

and

Adobe Photoshop Adobe Photoshop is a raster graphics editor developed and published by Adobe Inc. for Microsoft Windows, Windows and macOS. It was originally created in 1988 by Thomas Knoll, Thomas and John Knoll. Since then, the software has become the indu ...

, 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 with the original Macintosh personal computer on January 24, 1984. It was sold separately for US$195 with its word processing counterpart, MacWrite. MacPaint was nota ...

program developed by

Bill Atkinson Bill Atkinson (born March 17, 1951) is an American computer engineer and photographer. Atkinson worked at Apple Computer from 1978 to 1990. Atkinson was the principal designer and developer of the graphical user interface (GUI) of the Apple ...

. 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

With the selection problem in mind, Bill Atkinson went to his favorite

pub A pub (short for public house) is a kind of drinking establishment which is licensed to serve alcoholic drinks for consumption on the premises. The term ''public house'' first appeared in the United Kingdom in late 17th century, and was ...

Los Gatos Los Gatos (, ; ) is an List of municipalities in California, incorporated town in Santa Clara County, California, United States. The population is 33,529 according to the 2020 United States census, 2020 census. It is located in the San Franci ...

. Something on the wall caught his attention. It was an electric

Hamm's Beer The 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 ci ...

sign. The beer sign consisted of an illuminated scene of a kind of animated waterfall. Water seemed to flow down the waterfall into the lake. Bill figured that this effect could solve his problem because it is easily recognizable. He implemented the idea and showed it to Rod Perkins from the

Lisa Lisa or LISA may refer to: People People with the mononym * Lisa Lisa (born 1967), American actress and lead singer of the Cult Jam * Lisa (Japanese musician, born 1974), stylized "LISA", Japanese singer and producer * Lisa Komine (born 1978), J ...

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