L-System Explorer

Library

Grammar

Axiom

Rules, one per line

Write F = FF+[+F-F-F]. Add a weight for random growth: F(0.3) = F[+F]F.

Iterations

Turn angle

Start heading

Turtle

Depth shrink

Step scale

Angle jitter

Seed

Draws

Moves

Budget

Segment ceiling

Refit view after each change

Color source

Palette

Repeats

Shift

Wrap Reverse

Custom palette stops

Pick Custom blend in the palette list to use these.

Single color, used by Solid

Tone

Opacity

Saturation

Brightness

Backdrop

Fill

Colors

Line

Thickness

Taper

Overlap

Taper by depth Scale with zoom

Compositing

Blend

Bloom

Bloom amount

Bloom cutoff

Resolution

Pixel scale

Lower this if a big system feels sluggish on a phone.

View

Rotation

Spin

Animation

Palette drift

Draw itself on each rebuild

Draw time

Touch

Two fingers also rotate

Every symbol below is read by the turtle. Letters that do not appear in Draws or Moves are silent, so they can carry structure without leaving a mark.

F G: step forward, leaving a line
f g: step forward without drawing
+ −: turn left, turn right
|: turn around
[ ]: save and restore the turtle
> <: multiply, divide the step length
' `: next, previous color index
~: random turn within the angle

drag: pan; two fingers pinch to zoom
wheel: zoom at the pointer
dbl: zoom in; shift or two-finger tap zooms out
←↑→↓: pan
+ −: iterations up, down
[ ]: turn angle down, up
C: next color source
P: next palette
B: toggle bloom
R: surprise me
F: fit
S: save PNG
H: hide or show these controls

Geometry is built once per grammar change and kept on the GPU, so panning, zooming, recoloring and restyling never rebuild it. That is why color has so many knobs and none of them cost anything.