Strange attractors guide

Every control

Every control in the panel, top to bottom. The attractor and colour buttons and the parameter sliders are made when the page loads, so each has one line here. Camera, Mutation, Post-processing and Export start closed; tap their titles to open them.

Load and save

They stay at the top while the panel scrolls. Reset puts the controls back: the attractor you picked stays.

Save PNGButton: Saves the view, with the glow, as a PNG named after the attractor, such as lorenz-attractor.png. See PNG.
CopyButton: Copies a PNG of the view, with the glow, to the clipboard: the same picture Save PNG saves. See clipboard.

Attractor

Under the buttons, a line shows the frames drawn each second, how many points the trail holds (as 12k for 12,000), and the attractor's name.

AttractorPick one: Picks one of eight systems: Lorenz, Rossler, Chen, Aizawa, Thomas, Halvorsen, Sprott and Dadras. Picking one, even the one already running, clears the trail, puts its parameters back to their starting values, starts the path again from its own starting point, and sets Step size (dt) and Distance to values that suit it. See Lorenz attractor, Rössler attractor, Aizawa attractor, Thomas attractor, Halvorsen attractor and Dadras attractor.

Parameters

Parameter slidersFilled in by the tool: One slider for each constant in the attractor's rules, named as in the equations: sigma, rho and beta for Lorenz, a to f for Aizawa, b alone for Thomas. Each slider covers a range that suits its constant. The shape bends as the path follows the new rules; points already drawn stay until the trail replaces them. Some values stop the chaos, and the path settles to a dot or a single loop. See parameters.

Integration

Step size (dt)Slider · 0.0001 to 0.04 · starts at 0.005: How far forward in time each step moves the point. Bigger steps build the shape faster but follow the rules less closely. If the path runs away to huge numbers, it starts again from the starting point. See time step and Runge–Kutta method.
Steps per frameSlider · 10 to 100 · starts at 30: How many steps run before each picture is drawn. Higher fills the trail faster and moves the path faster, and asks more of your device. See steps per frame.

Trail

The trail is a ring of points: once it is full, each new point replaces the oldest.

Max pointsSlider · 10000 to 200000 · starts at 50000: How many points the trail keeps. Moving it clears the trail and starts a new one. On phones and touch screens it opens at 20k and stops at 100k. See max points.
Point sizeSlider · 0.5 to 5 · starts at 1.5: How big each point is drawn. Points nearer the camera are drawn bigger. See point size.

Color

ColorPick one: How the points are coloured. Velocity runs from blue for the slowest to red for the fastest the path has moved. Position mixes red, green and blue from where each point sits across x, y and z. Age paints the newest points bright orange, fading to dark red for the oldest. Solid paints them one colour and shows the colour picker below. Except for Age, a new choice colours only the points drawn after it. See colour by velocity, colour by position and particle age.
ColorColour · starts #10B981: The one colour Solid uses. It shows only while Solid is picked, and it too colours only new points. See hex colour.

Camera

Auto-rotateOn or off · starts on: Turns the view slowly on its own. You can still drag to turn it. See auto-rotate.
DistanceSlider · 5 to 200 · starts at 80: How far the camera sits from the middle of the scene, from 5 to 200. Moving it glides the camera to the new distance; a scroll or a pinch over the view moves the camera too, and the slider follows. Picking an attractor sets its own distance; the page opens at 60, Lorenz's. See orbit camera.

Mutation

Drift the parametersOn or off · starts off: Swings each parameter slowly up and down around the value you set, by up to 15% of its slider's range and each at its own pace; the sliders move to show it. Turned off, the parameters stop where they are, and any you moved by hand go back to your value.
SpeedSlider · 0.01 to 1 · starts at 0.1: How fast the parameters swing while Drift the parameters is on.

Post-processing

Bloom strengthSlider · 0 to 2 · starts at 0.5: How strong the glow around bright points is. At 0 there is no glow. See bloom.
Bloom thresholdSlider · 0 to 1 · starts at 0.1: How bright a part of the picture must be before it glows. See bloom threshold.

Reset

ResetButton: Puts the steps, trail, point size, glow and drift speed back to how the page opened, turns Auto-rotate on and Drift off, sets the colour back to Velocity and the solid colour to green, and starts the current attractor afresh.