# METABALLS

## BY ROLF TIMMERMANS •

Metaballs, or *blobby objects*, are organic looking three-dimensional surfaces. They are defined implicitly by mathematical functions, instead of explictly by enumerating the points that make up the object. We define an equation and the surface represents all points where it equals.

First, we take the distance from the metaball centre. Then we subtract a constant value. All points inside the surface are negative, all points outside the surface are positive. This is called a *signed distance field*. Combining multiple metaballs means their fields influence each other. Metaballs that are close to each other will have their surfaces merged, which causes the characteristic organic look.