Copy/Paste the following code to your GroIMP project:
//**********************************************************
/* You will learn with this example:
– how to keep the branching order as a parameter and how to get
access to its value in a condition.
– (Compare the resulting growth behaviour with the preceding
example.)
*/

module Shoot(float len) extends F(len);
module Bud(int order, float strength) extends Sphere(0.2) // order as param.
{{setShader(RED); setTransform(0,0,0.3);}};

const float APICAL_REDUCTION_FACTOR = 0.95;
const float MAX_ORDER_ALLOWED = 2;

//—————————————————-/

// Start block with the start word
protected void init()
[ Axiom ==> Bud(0, 5); ]

// public rule block
public void grow()
[
b:Bud(o, x), (b[order] <= MAX_ORDER_ALLOWED) ==> Shoot(x)
[ RU(50) Bud(o+1, 0.7*x) ] [ RU(-50) Bud(o+1, 0.7*x) ]
Bud(o, APICAL_REDUCTION_FACTOR * x);
]