Rainbow

- XLogo

This draw a simple rainbow. The colors are chosen in order from a color list. The six colored bands are drawn with the arc command.

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

To Rainbow
  SetPW 10     # big pen
  Make "Cols [1 13 3 2 4 15]
  For [N 1 6] [
    SetPC Item :N :Cols
    Arch 180 (180-12*:N) Wait 30]
End

To Arch :Angle :Radius
  # symmetrical arc drawn relative to turtle heading
  Arc :Radius Heading-:Angle/2 Heading+:Angle/2
End

To Go
  New Rainbow
End

An alternative procedure, where the color names are used instead of numbers.

To Rainbow
  SetPW 10     # big pen
  Make "Cols [Red Orange Yellow Green Blue Purple]
  For [N 1 6] [
    SetPC Run Item :N :Cols
    Arch 180 (180-12*:N) Wait 30]
End

Rainbow
Rainbow

Procedures blue
Variables pink
Comments green
Library gray