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Scene language

Updated on August 5, 2026

SimuLab scenes are not drawn with a graphical editor: they are described by writing. This means you can define exactly which figures appear, how they move, and from which viewpoint, using a simple language designed for science problems.

Where to edit a scene

When creating or editing a problem manually, scroll down to the Statement section of the editor. Below the statement text you will find a monospace text field with the placeholder Simulation code. That is where you write the code. The Preview button runs the scene in a preview box so you can see it before saving.

General structure

A scene has two main parts:

  1. The scene block, which defines the scene type (2d or 3d), the visible area, and all the figures.
  2. One or more anim blocks, which define how figures move or change over time, using the format anim start..end.

Inside an anim block, each animation line can be prefixed with @start..end to specify during which time interval that particular animation occurs.

Available element families

2D scenes

Element Purpose
point Marks a position with a dot and an optional label
vector Arrow with direction and magnitude
segment Segment between two points
line Infinite line through two points
circle Circle, filled or outline only
rect Rectangle
polygon Polygon with as many vertices as you need
curve Curve defined by a mathematical function
label Text positioned in the scene
emitter Particle emitter (fluids, fields)
axis Cartesian axes with labels

3D scenes

Element Purpose
sphere Sphere in space
box Rectangular box
cylinder Cylinder
plane Plane
arrow3 Arrow in 3D
molecule Molecule from its SMILES formula
camera Configures the initial camera view

Available animations

Animations are written in anim blocks, naming the figure they apply to. The main ones are:

Animation What it does
move Moves the figure to another position
rotate Makes it rotate
scale Changes its size
fade Changes its opacity
oscillate Makes it oscillate around a point
orbit Makes it orbit around another element
follow Moves it along a curve
trace Draws the path it travels
spin Continuous rotation around an axis
pulse Makes the size pulse
flow Generates a particle flow over the figure
show / hide Shows or hides the figure
set Changes a property at a specific moment

Minimal example

The following code defines a 2D scene with a point that moves to the right:

scene 2d
  space x=-5..5 y=-5..5
  point A at (0, 0) color=blue label="A"
anim 0..3
  move A to (4, 0)

This example creates a two-dimensional scene, sets the visible area between −5 and 5 on both axes, places a point named A at the origin in blue, and defines an animation from 0 to 3 seconds that moves it to position (4, 0).

The scene is optional when creating a problem. If you do not add any code, the problem works just fine but without the animated visualization.

Frequently asked questions

Do I need programming knowledge to write scenes? No. The language is designed to be readable: each line describes a figure or a motion in words that resemble what they do. A few minutes of practice with the examples as reference is enough.

What colors can I use? The available color names are: red, blue, green, yellow, orange, purple, cyan, magenta, white, black, and gray.

Can I use mathematical formulas in values? Yes. Expression fields accept operations with sin, cos, sqrt, exp, abs, ln, log, pow, and other functions. You can also use the constants pi, e, and t (the animation time).

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