Metaballs sim is a relaxing fluid sandbox where dozens of soft water blobs fall, pool and merge into one gooey, rolling surface.
How it works. Two things run at once. Behind the scenes a lightweight particle simulation gives every blob gravity, plus viscosity and cohesion forces that pull neighbours together and let overlaps relax apart, so the crowd flows and settles like a thick liquid. On screen it uses the classic metaball trick: in a first pass each blob splats a soft circular field into an offscreen texture using additive blending, so wherever two blobs sit close their fields add up; a second full-screen pass then thresholds that combined field into flat colour bands — edge, fill and a bright dense core — making separate circles visually fuse into a single liquid shape. Everything is drawn with WebGL2 in just a couple of draw calls.
How you interact:
- Drag — swirl the pool; blobs near your finger get pulled along with it.
- Tap the top — pours fresh blobs in from above that drip down and merge into the water.
- Cycle — hold to roll the colour smoothly through the spectrum, release to keep whatever hue it lands on.
- Size + / Size - — makes newly poured blobs bigger or smaller.
- Reset — clears everything back to the neat starting grid and the default blue.
- Full screen — fills the display for the full effect.
A self-contained demo that runs completely offline.