func handleLSystemPng(w http.ResponseWriter, r *http.Request, rr render.Render) {
err := r.ParseForm()
if err != nil {
turtleError(w)
return
}
// Parse form into an LSystem
sys := LSystem{}
err = sys.ParseForm(r.Form)
if err != nil {
turtleError(w)
return
}
// Execute lsystem
size := 780
i := image.NewRGBA(image.Rect(0, 0, size, size))
t := terrapin.NewTerrapin(i, terrapin.Position{
float64(size) / 2,
float64(size) / 2,
})
sys.Execute(t)
png.Encode(w, i)
}
func main() {
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte(`
<!doctype html>
<title>Terrapin example</title>
<h1>Terrapin example</h1>
<img src="/example1.png">
<img src="/example2.png">
`))
})
http.HandleFunc("/example1.png", func(w http.ResponseWriter, r *http.Request) {
i := image.NewRGBA(image.Rect(0, 0, 300, 300))
t := terrapin.NewTerrapin(i, terrapin.Position{150.0, 150.0})
s := 20.0
// Triangle
t.Forward(s)
t.Right(math.Pi * 1 / 2)
t.Forward(s)
t.Right(math.Pi * 3 / 4)
t.Forward(math.Hypot(s, s))
png.Encode(w, i)
})
http.HandleFunc("/example2.png", func(w http.ResponseWriter, r *http.Request) {
i := image.NewRGBA(image.Rect(0, 0, 300, 300))
t := terrapin.NewTerrapin(i, terrapin.Position{150.0, 150.0})
// Polygons!
poly(t, 20.0, 3)
poly(t, 40.0, 5)
poly(t, 60.0, 7)
png.Encode(w, i)
})
fmt.Println("Listening on http://localhost:3000")
log.Fatalln(http.ListenAndServe(":3000", nil))
}
func turtleError(w io.Writer) {
size := 780
x := 50.0
i := image.NewRGBA(image.Rect(0, 0, size, size))
t := terrapin.NewTerrapin(i, terrapin.Position{
float64(size)/2 - x*5,
float64(size)/2 - x*5,
})
for _, c := range "ERROR" {
switch c {
case 'E':
t.Right(math.Pi / 2)
t.Forward(x)
t.Right(math.Pi)
t.Forward(x)
t.Left(math.Pi / 2)
t.Forward(x)
t.Left(math.Pi / 2)
t.Forward(x)
t.Right(math.Pi)
t.Forward(x)
t.Left(math.Pi / 2)
t.Forward(x)
t.Left(math.Pi / 2)
t.Forward(x * 2)
t.Left(math.Pi / 2)
case 'R':
t.Forward(x * 2)
for i := 0; i < 3; i++ {
t.Right(math.Pi / 2)
t.Forward(x)
}
t.Left(math.Pi * 3 / 4)
t.Forward(math.Hypot(x, x))
t.Left(math.Pi / 4)
t.Forward(x)
t.Left(math.Pi / 2)
case 'O':
for i := 0; i < 2; i++ {
t.Forward(x * 2)
t.Right(math.Pi / 2)
t.Forward(x)
t.Right(math.Pi / 2)
}
t.Right(math.Pi / 2)
t.Forward(x * 2)
t.Left(math.Pi / 2)
}
}
png.Encode(w, i)
}