Metaballs Screensaver
The Metaballs screensaver renders organic blobs that drift, merge and split using real metaball isosurface math. It is free, runs in your browser, and ESC exits.
Live preview
Press ESC to leave fullscreen. Settings are saved in your browser only.
How the Metaballs screensaver works
The saver computes a real scalar field as the sum of influence from several moving point sources.
A single smooth surface is drawn wherever that field crosses a threshold, producing the organic metaball look.
As sources drift closer, their fields merge into one blob; as they separate, the blob splits again.
This is the same real isosurface technique used throughout computer graphics for liquid-like shapes.
Blobby graphics from Blinn to marching squares
Metaballs trace back to Jim Blinn’s 1982 paper “A Generalization of Algebraic Surface Drawing”, developed in the early 1980s to depict atom interactions, including for Carl Sagan’s television series Cosmos. Each ball is not a solid sphere but a source of influence that falls off smoothly with distance from its centre.
The look comes from adding those influences together. Where two balls are far apart the summed field is low between them, so you see two separate blobs. As they approach, the fields overlap and add, the field between them climbs above the threshold, and a neck of surface appears that thickens until the two become one. Because the falloff is smooth rather than sharp, the neck is rounded instead of showing a crease.
Turning a field into a visible outline is a separate problem. In three dimensions, marching cubes is one of the two most common ways to render metaballs, the other being brute-force ray casting. Marching cubes works cell by cell and builds a triangle mesh along the threshold, and its two-dimensional counterpart, marching squares, draws the line segment that follows the threshold through each cell of a flat grid.
A worked example
Two drifting blobs approach and merge into a single organic shape with a smooth connecting neck, then separate again as they drift apart.
Settings & tips
- Accent recolours the blob surface.
- Based on the real metaball isosurface technique used in graphics.
- Blobs merge and split smoothly as sources move.
Frequently asked questions
- Is this a real graphics technique?
- Yes — real metaball isosurface math, used throughout computer graphics.
- Is a key needed?
- No — it is a pure local simulation.
- Is it free?
- Yes — free, no download, in your browser.
- How many blobs are there?
- A handful of moving sources, tuned for a smooth, uncluttered look.
- Why do the blobs stretch toward each other before touching?
- Their influence fields overlap before their centres meet, so the summed value between them rises above the threshold while a gap still exists. The neck you see is the iso-line following that raised field.
- What is the difference between a metaball and a simple circle?
- A circle has a hard edge fixed by its radius, so overlapping circles just overlap. A metaball's edge is wherever the total field crosses a level, which depends on every ball nearby, so shapes can bulge, merge and pinch off.
- Who invented metaballs?
- Jim Blinn described the technique in his 1982 paper “A Generalization of Algebraic Surface Drawing”, created to depict atom interactions.