Metaballs

In computer graphics, metaballs, also known as blobby objects,[1][2] are organic-looking n-dimensional isosurfaces, characterised by their ability to meld together when in close proximity to create single, contiguous objects.

A metaball's "blobby" appearance makes them versatile tools, often used to model organic objects and also to create base meshes for sculpting.

[3] The technique for rendering metaballs was invented by Jim Blinn in the early 1980s to model atom interactions for Carl Sagan's 1980 TV series Cosmos.

[4] It is also referred to colloquially as the "jelly effect" in the motion and UX design community,[5] commonly appearing in UI elements such as navigations and buttons.

; three-dimensional metaballs tend to be most common, with two-dimensional implementations popular as well).

A typical function chosen for metaballs is simply inverse distance, that is, the contribution to the thresholding function falls off asymptotically toward zero the distance from the centre of the metaball increases: where

Desirable properties of the function include: More complicated models use an inverse square law, or a Gaussian potential constrained to a finite radius or a mixture of polynomials to achieve smoothness.

The Soft Object model by the Wyvill brothers provides higher degree of smoothness.

[citation needed] A simple generalization of metaballs is to apply the falloff curve to distance-from-lines or distance-from-surfaces.

In the case of three dimensional metaballs, the two most common are brute force raycasting and the marching cubes algorithm.