Orbit Explorer

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Earth

This is similar to Pursuit curves. Three turtles are created. Turtle 3 orbits turtle 2, turtle 2 orbits turtle 1 and turtle 1 orbits turtle 3. Hence all three turtles are locked together. They are each given a weight. This determines how fast they orbit. The speed is calculated as Distance divided by the weight.

This is still an experimental program. Add another weight into the list for four orbiting turtles. This is very random / unstable.

To New
  # set default screen, pen and turtle values
  ResetAll SetScreenSize [400 400] HideTurtle
  SetSC Black SetPC Green SetPS 1 PenUp
End

To Init :N
  If :N <2 [Print [Need more than one turtle!] Stop]
  # Make "Weights [8 -4 2]
  # Make "Weights [8 -4 24]
  # Make "Weights [8 -14 11]   # neat
  # Make "Weights [13 -5 -9]
  Make "Weights [20 -14 8]
  Repeat :N [
    SetTurtle RepCount
    Make "Angle RepCount*360/:N
    SetPC Hue :Angle PenUp
    SetXY (40*Sin :Angle) (40*Cos :Angle) PenDown]
End

To Hue :Theta
  # Output RGB hue list from angle :Theta
  Make "Red Round 127.5*(1+Sin :Theta)
  Make "Green Round 127.5*(1+Sin (:Theta+120))
  Make "Blue Round 127.5*(1+Sin (:Theta+240))
  Output (List :Red :Green :Blue)
End

To Go :N
  New SetTurtlesMax :N+2 Init :N
  Forever [
    Repeat :N [
      SetTurtle RepCount Make "myPos Pos
      SetTurtle RepCount+1
      If RepCount+1>:N [SetTurtle 1]
      HideTurtle SetH Towards :myPos
      Make "Dist Distance :myPos
      Left 90 ShowTurtle
      Forward (Item RepCount :Weights) /:Dist ] ]
End

Also see Spiro Explorer

Orbits
Orbits

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