Copy/Paste the following code to your GroIMP project:
//**********************************************************
/*
You will learn with this example:
– how to modify a simple model of a triangle to extend it to a Koch curve
– your first “proper” rule application
– the definition of a public method “application” (rule application)
*/

//—————- Example Koch curve ————————————-
// each line will be replaced by 4 lines with length = (original length / 3)

protected void init()
[
Axiom ==> RU(50) F(10) RU(120) F(10) RU(120) F(10);
]

// pubic method for the interactive use in GroIMP (via button)
public void application()
// rules must be put in [] – brackets and must be finished with ;
[
// each F() is replaced by 4 smaller F()
// the length of the F at the left-hand side of the rule
// is taken over to the right-hand side
F(x) ==> F(x/3) RU(-60) F(x/3) RU(120) F(x/3) RU(-60) F(x/3);
]

//**********************************************************