Task: Koch curve




Go: package main

import (
    "github.com/fogleman/gg"
    "math"
)

var dc = gg.NewContext(512, 512)

func koch(x1, y1, x2, y2 float64, iter int) {
    angle := math.Pi / 3 
    x3 := (x1*2 + x2) / 3
    y3 := (y1*2 + y2) / 3
    x4 := (x1 + x2*2) / 3
    y4 := (y1 + y2*2) / 3
    x5 := x3 + (x4-x3)*math.Cos(angle) + (y4-y3)*math.Sin(angle)
    y5 := y3 - (x4-x3)*math.Sin(angle) + (y4-y3)*math.Cos(angle)
    if iter > 0 {
        iter--
        koch(x1, y1, x3, y3, iter)
        koch(x3, y3, x5, y5, iter)
        koch(x5, y5, x4, y4, iter)
        koch(x4, y4, x2, y2, iter)
    } else {
        dc.LineTo(x1, y1)
        dc.LineTo(x3, y3)
        dc.LineTo(x5, y5)
        dc.LineTo(x4, y4)
        dc.LineTo(x2, y2)
    }
}

func main() {
    dc.SetRGB(1, 1, 1) 
    dc.Clear()
    koch(100, 100, 400, 400, 4)
    dc.SetRGB(0, 0, 1) 
    dc.SetLineWidth(2)
    dc.Stroke()
    dc.SavePNG("koch.png")
}





VB: option explicit


const pi180= 0.01745329251994329576923690768489 
const pi=3.1415926535897932384626433832795 
class turtle
   
   dim fso
   dim fn
   dim svg
   
   dim iang  
   dim ori   
   dim incr
   dim pdown
   dim clr
   dim x
   dim y

   public property let orient(n):ori = n*pi180 :end property
   public property let iangle(n):iang= n*pi180 :end property
   public sub pd() : pdown=true: end sub 
   public sub pu()  :pdown=FALSE :end sub 
   
   public sub rt(i)  
     ori=ori - i*iang:
     if ori<0 then ori = ori+pi*2
   end sub 
   public sub lt(i):  
     ori=(ori + i*iang) 
     if ori>(pi*2) then ori=ori-pi*2
   end sub
   
   public sub bw(l)
      x= x+ cos(ori+pi)*l*incr
      y= y+ sin(ori+pi)*l*incr
   end sub 
   
   public sub fw(l)
      dim x1,y1 
      x1=x + cos(ori)*l*incr
      y1=y + sin(ori)*l*incr
      if pdown then line x,y,x1,y1
      x=x1:y=y1
   end sub
   
   Private Sub Class_Initialize()  
      setlocale "us"  
      initsvg
      pdown=true
   end sub
   
   Private Sub Class_Terminate()   
      disply
   end sub
   
   private sub line (x,y,x1,y1)
      svg.WriteLine "<line x1=""" & x & """ y1= """& y & """ x2=""" & x1& """ y2=""" & y1 & """/>"
   end sub 

   private sub disply()
       dim shell
       svg.WriteLine "</svg></body></html>"
       svg.close
       Set shell = CreateObject("Shell.Application") 
       shell.ShellExecute fn,1,False
   end sub 

   private sub initsvg()
     dim scriptpath
     Set fso = CreateObject ("Scripting.Filesystemobject")
     ScriptPath= Left(WScript.ScriptFullName, InStrRev(WScript.ScriptFullName, "\"))
     fn=Scriptpath & "SIERP.HTML"
     Set svg = fso.CreateTextFile(fn,True)
     if SVG IS nothing then wscript.echo "Can
     svg.WriteLine "<!DOCTYPE html>" &vbcrlf & "<html>" &vbcrlf & "<head>"
     svg.writeline "<style>" & vbcrlf & "line {stroke:rgb(255,0,0);stroke-width:.5}" &vbcrlf &"</style>"
     svg.writeline "</head>"&vbcrlf & "<body>"
     svg.WriteLine "<svg xmlns=""http://www.w3.org/2000/svg"" width=""800"" height=""800"" viewBox=""0 0 800 800"">" 
   end sub 
end class

sub koch (n,le)
  if n=0 then x.fw le :exit sub
  koch n-1, le/3
  x.lt 1
  koch n-1, le/3
  x.rt 2
  koch n-1, le/3
  x.lt 1
  koch n-1, le/3
end sub

 dim x,i
set x=new turtle
x.iangle=60
x.orient=0
x.incr=3
x.x=100:x.y=300
for i=0 to 3
  koch 7,100
  x.rt 2
next  
set x=nothing