metaballs
5Such expressive visuals seen in metaballs become possible thanks to a simple yet powerful mathematical tool called a distance function, which measures how far any given pixel is from a shape’s center. By varying visual intensity based on distance, diverse visual expressions naturally emerge. Particularly distinctive in metaballs is the use of the inverse-square law, meaning that intensity rapidly increases as you move closer, and smoothly fades away with distance. This inverse-square relationship is widespread in physics—examples include Newton's law of universal gravitation, which describes gravity, and Coulomb's law, governing electric forces.
Metaballs cleverly exploit this rule by summing the influences of multiple circles or spheres, allowing their boundaries to blend naturally. This approach originated in 1982 with Kazuo Murakami and Tomoyuki Nishita, who first introduced “Metaballs” in computer graphics. Subsequently, researchers like Paul Bourke further popularized it. The technique became especially prominent in the Demoscene, a community focused on creating stunning, real-time visual effects through compact code. Technologies like Shaders, which harness GPU capabilities, made these real-time graphics feasible, with platforms like ShaderToy and languages like GLSL (OpenGL Shading Language) empowering artists and developers to experiment quickly and visually.
Today, metaball techniques extend widely into interactive experiences and art, appearing frequently in game development environments such as Unity and Unreal Engine. Additionally, professional animation and visual-effects software like Houdini leverage metaballs through advanced volume modeling features, alongside sophisticated distance-based methods known as Signed Distance Fields (SDF), enabling creators to generate lifelike and compelling visual effects for films, games, and interactive art installations.