LABEL text

Prints text to the screen at the turtle's current position and heading.

You can print any Logo thing (numbers, lists, strings, etc.). If text is a list, then any sub-lists are delimited by square brackets, but the entire object is not delimited by brackets. The text is truncated according to the current values of PRINTWIDTHLIMIT and PRINTDEPTHLIMIT.

The text is printed in the font described by LABELFONT, which is set with SETLABELFONT or the Set->Label Font menu item.

The position of the text is determined by the location of the turtle. More precisely, the top-left corner of the text is placed at the turtle's position.

The angle of the text is determined by the heading (direction) of the turtle. Not all fonts are capable of printing text at different angles, so be sure to use a TrueType or OpenType font if printing at different angles is desired.

The color of the text is determined by the value of PENCOLOR, which is set with SETPENCOLOR.

The width and height of the text's bounding box can be determined with LABELSIZE.

LABEL can be used in PERSPECTIVE mode, but the text is not printed on the same plane as the turtle. Instead, the text is placed wherever the turtle is on the screen (in two dimensions) and oriented according to the turtle's heading.

The capabilities of the text changes depending on the device (screen or printer), the turtle heading (direction), and the font. In other words, sometimes the text can be drawn at the turtle heading and sometimes it cannot. Sometimes what is on the screen is not exactly what you print.

If you want to flash a message by writing it in one color, then writing the same message in the background color, you should disable anti-aliasing in the LABELFONT by choosing a Quality of 3 when you run SETLABELFONT. Otherwise, you'll end up with a faint outline of the message which you wanted to completely erase.

; label the axes of a 3D Cartesian Coordinate System
TO AXIS
  SETLABELFONT [[Courier New] -19 0 0 700 0 0 0 0 3 2 1 49]
  RIGHT 90

  SETY  200
  LABEL "+Y
  SETY  -200
  LABEL "-Y
  SETY 0

  SETX 200
  LABEL "+X
  SETX -200
  LABEL "-X
  SETX 0

  SETZ 200
  LABEL "+Z
  SETZ -200
  LABEL "-Z
  SETZ 0
  LEFT 90
END

PERSPECTIVE
CLEARSCREEN
SETTURTLE -1 ; select the eye position
SETPOSXYZ [600 600 800]
SETTURTLE 0
AXIS

; flash a message
TO FLASH :message
  ; Quality=3 disables anti-aliasing
  SETLABELFONT [[Arial] -19 0 0 700 0 0 0 0 3 2 3 49]
  PENPAINT
  LABEL :message
  WAIT 180
  PENERASE
  LABEL :message
  PENPAINT
END

TO TELLJOKE
  FLASH [Q: Why did the chicken cross the road?]
  FLASH [A: To get to the other side!]
  FLASH [Ha! ha! ha!]
END