Physarum trails guide

Help

Short answers to what goes wrong most often.

The frame says the effect needs WebGL

Physarum trails needs WebGL 2 with floating-point render targets, and this browser does not offer them. Turn on the browser's graphics acceleration, update it, or try another current browser.

Tapping the picture changes little

A tap only scatters the agents already inside a small circle round the tap, about a third of the picture's height across. Where few agents are, little changes, and the trail already laid stays until it fades. To start the whole network again, press Replay. A tap only counts with the main mouse button or a finger.

Picture B never shows

Check that A → B transition under Sliders is on, then press Replay. It starts on, and presets and Reset keep it on.

The picture is stuck on B

With A → B transition on, picture B stays once a run ends. Press Replay to start again from A, or turn the switch off to go straight back to A.

My picture looks stretched

The frame takes the shape of picture A, and picture B is stretched to that shape. Crop both pictures to the same shape first. Replacing A changes the frame's shape and starts a fresh colony; replacing B does neither.

My picture did not change

A file the browser cannot open as an image is skipped without a message. Try a JPEG, PNG or WebP copy of it. See JPEG, PNG and WebP.

The threads look wrong or vanish

With a high Filament floor and a low Deposit, too little trail builds up to glow; lower the floor or raise Deposit. A Filament peak below the floor is read as just above it, so only the busiest paths glow.

It is slow, or the page struggles

The number of agents costs the most. Pick 256 · 65k under Agents. The trail map is at most 512 cells on its long side whatever the picture, but the pictures go to the graphics card at their full size, so a very large photo takes more memory. Use a smaller copy on a phone or an older computer.

Record video did nothing

The line under the buttons says why: some browsers cannot record a canvas, or offer no video format the page can use. Try a current Chrome, Edge or Firefox.

Where do my pictures go?

Nowhere. They are opened in your browser and drawn on your graphics card. Nothing is uploaded. The pictures you add stay on this device, in this browser, so the other lab tools can open them too; × on a picture removes it.

Are there keyboard shortcuts?

The tool has none of its own. Anywhere in the lab, Ctrl K, or Cmd K on a Mac, opens the list of all tools.

On a phone

It works with a finger: tap the picture to scatter the agents there. The page starts with the smallest colony, 256 · 65k, and presets and Reset keep it there. The controls sit in a bar at the bottom of the screen; tap the bar to open them.