Instructions:

Use the mouse to draw in the large image area. Alternate clicks paint "high-U" (red in the default colours) or "low-U" (blue).

The init button makes the pattern blank, or random. Click it multiple times until you get what you want.

Use the list of presets to see examples of patterns from the wide diversity of types available. Each preset has a classification (usually a Greek letter); these are explained on the separate page Pearson's Classification (Extended) of Gray-Scott System Parameter Values.

• Negative bubbles (sigma) : Hit Init until you get blue spots on a red background. They will grow, but not join; you'll end up with blue bubbles separated by red lines.
• Positive bubbles (rho) : Hit Init until you get a red and blue "Swiss cheese" type pattern. Small bubbles will coalesce into larger ones.
• Precritical bubbles (rho/kappa) : Start with either of the preceding examples (sigma or rho), then switch to this one.
• Worms and loops (kappa) : Hit Init until you get blue spots on a red background.
• Stable solitons (nu) : Hit Init until you get a blank red background. Then draw a few individual blue dots close to each other. They will either merge into one or repel each other.
• The U-Skate World (pi) : Start with a blank all-blue background, then slowly paint a small letter "u" in red. If you get it just right, it will become a U-Skate and travel across the screen. Try making U-Skates crash into each other.
• Worms (mu) : Start with a random pattern or by scribbling in blue on a blank red background.
• Worms join into maze (kappa) : Start the same way you did with "Worms (mu)" and notice the differences.
• Negatons (iota) : On a plain red background, scribble randomly with blue. Watch how it becomes an aqua-green screen with some yellow dots that arrange into hexagonal-grid rows.
• Turing patterns (delta) : Hit Init until you get a plain green background, then click in it 3 or 4 times with the mouse. It seems that nothing happened -- but stop clicking and wait. A pattern will emerge seemingly from nowhere.
• Chaos to Turing negatons (beta) : Do the same thing as with "Negatons (iota)" or "Turing patterns (delta)". Note similarities and differences.
• Fingerprints (theta/kappa) : Start with a random pattern or by scribbling in blue on a blank red background.
• Chaos with negatons (beta/delta) : Start as suggested for "Turing patterns (delta)", or with either or the random patterns.
• Spots and worms (eta) : Start the same way you did with "Worms (mu)" and notice the differences.
• Self-replicating spots (lambda) : Hit Init until you get a single blue-green spot on a red background, then watch it multiply.
• Super-resonant mazes (theta) : Hit Init until you get the blank green background, then click just once with the mouse.
• Mazes (kappa) : Start with a random pattern or by scribbling in blue on a blank red background.
• Mazes with some chaos (gamma) : Same suggestions as for "Mazes (kappa)"; after you get a full maze try switching the preset back and forth between these two.
• Chaos (beta) : Hit Init until you get the blank green background, then click just once with the mouse.
• Pulsating solitons (zeta) : Start as with "Self-replicating spots (lambda)" and note the different behaviour that starts after the screen is full.
• Warring microbes (epsilon) : Start with a blank red background, then add two or three blue dots.
• Spots and loops (alpha) : Start with a blank red background, then add a single blue dot.
• Moving spots (alpha) : Start with a blank red background, then add a single blue dot.
• Waves(xi) : Use Init until you get a plain greenish-yellow background, then use the mouse to draw a circle. This should produce long-lasting spiral waves.

You may also change F, k directly with the sliders. Make small, gradual changes (if you change these quickly, the pattern will probably vanish)

Edit the colour scheme by clicking on the little squares below the colour bar to access a colour-picker dialogue.

When you find values of F, k, and colour scheme you like, you can save them by copying the text out of the box labeled "Import/export". To restore previously-saved settings, paste the text into the box and hit Enter.

This simulation requires the GL extensions framebuffer_object and texture_float. If you cannot see the simulation your system probably lacks at least one of these extensions.

In Google Chrome, you can see the available GL extensions by putting chrome://gpu in the address bar.