func (sys *LSystem) Execute(t *terrapin.Terrapin) {
// Rewrite
state := sys.StartState
for i := 0; i < sys.Iterations; i++ {
for from, to := range sys.Rules {
state = strings.Replace(state, from, strings.ToLower(to), -1)
}
state = strings.ToUpper(state)
}
// Run turtle
for _, a := range state {
def := sys.Definitions[string(a)]
value := float64(def.Value)
valueRad := value * (math.Pi / 180)
switch def.Function {
case "fwd":
t.Forward(value)
case "left":
t.Left(valueRad)
case "right":
t.Right(valueRad)
}
}
}
func poly(t *terrapin.Terrapin, size float64, sides int) {
totalInterior := math.Pi * float64(sides-2)
interior := totalInterior / float64(sides)
exterior := math.Pi - interior
// Get into position
t.PenUp()
t.Forward(size / 2)
t.Right(math.Pi/2 + exterior/2)
t.PenDown()
// Draw it
for i := 0; i < sides; i++ {
t.Forward(size)
t.Right(exterior)
}
// Get back to where we started
t.PenUp()
t.Left(math.Pi/2 + exterior/2)
t.Backward(size / 2)
t.PenDown()
}