-This is the script file used for the turtle tutorial.


#cls(1)
#move(200,100)
#setpen(2)
#text("T U R T L E    T U T O R I A L")
#move(195,104)
#text("________________________________")
#move(198,99)
#setpen(7)
#text("T U R T L E    T U T O R I A L")
#move(193,103)
#text("________________________________")
#setpen(2)
#move(30,180)
#text("This tutorial explains the ideas behind producing pictures using the turtle")
#move(10,200)
#text("program. For help on using the menu options within the program itself, select")
#move(10,220)
#text("Help from the Project Menu.")
#move(30,240)
#text("The tutorial will cycle through a number of screens automatically. To pause") 
#move(10,260)
#text("the tutorial on a screen, hold down the right mouse button.")
#move(60,300)
#text("Press <Esc> to exit the tutorial.")
#wait(480)
#cls(1)
#move(30,140)
#text("Turtle uses turtle graphics like logo. It uses an imaginary turtle whose")
#move(10,160)
#text("position is the current drawing position. The position may be from 0,0")
#move(10,180)
#text("(top left) to 640,512 (bottom right). The turtle also has a heading,")
#move(10,200)
#text("which is the direction in which the turtle faces - straight up is a heading")
#move(10,220)
#text("of zero, right is 90, down is 180, etc:")
#set_heading(0)
#set_length(60)
#set_angle(90)
#setpen(7)
#move(320,340)
#run([F]+[F]+[F]+[F])
#move(316,276)
#text("0")
#move(308,416)
#text("180")
#move(382,346)
#text("90")
#move(234,346)
#text("270")
#wait(180)

#cls(1)
#setpen(2)
#move(30,140)
#text("Turtle takes an input string and produces a drawing dependent on the")
#move(10,160)
#text("characters in the string:")
#setpen(7)
#move(100,220)
#text("'F'  :    moves the turtle forward, drawing a line.")
#move(100,240)
#text("'f'  :    moves the turtle forward without drawing.")
#move(100,280)
#text("'-'  :    makes it turn left.")
#move(100,300)
#text("'+'  :    makes it turn right.")
#move(100,320)
#text("'['  :    pushes (saves) the current state.")
#move(100,340)
#text("']'  :    pops the current state (retrieves the latest saved one).")
#setpen(2)
#move(10,400)
#text("Other characters are ignored.")
#wait(240)

#cls(1)
#setpen(2)
#move(30,140)
#text("Several parameters are needed by the program to do its drawing. These")
#move(10,160)
#text("are specified in control statements, starting with a '#'.")
#move(30,180)
#text("The statements are:")
#setpen(7)
#move(100,240)
#text("#move(X,Y)     :   Move the turtle to position X,Y.")
#move(100,260)
#text("#setpen(N)     :   Set the drawing colour to N.")
#move(100,280)
#text("#set_length(N) :   Set the distance the turtle moves forward to N.")
#move(100,300)
#text("#cls(N)        :   Clear the screen to colour N")
#move(100,320)
#text("#set_heading(N):   Set the turtle heading to N.")
#move(100,340)
#text("#set_angle(N)  :   Set the angle through which the turtle turns.")
#move(100,360)
#text("#text(STRING)  :   Output the string STRING at current position.")
#move(100,380)
#text("#wait(N)       :   Wait N/60 seconds.")
#move(30,450)
#setpen(2)
#text("Any line starting with a '-' is considered a comment.")
#wait(240)

#cls(1)
#move(30,140)
#text("A string is drawn using the command #run(STRING), e.g.:")
#move(50,200)
#text("#run(F) will produce a straight line:")
#move(50,280)
#text("#set_angle(120)")
#move(50,300)
#text("#run(F+F+F) will produce a triangle:")
#move(50,320)
#text("(Forward, Right 120, Forward, Right 120, Forward)")
#move(50,380)
#text("#set_angle(90)")
#move(50,400)
#text("#run(F+F+F+F) will produce a square:")
#set_length(40)
#setpen(4)
#set_heading(0)
#move(400,220)
#run(F)
#move(460,300)
#set_heading(30)
#set_angle(120)
#run(F+F+F)
#move(400,400)
#set_angle(90)
#set_heading(0)
#run(F+F+F+F)
#wait(180)

#cls(1)
#setpen(2)
#move(10,135)
#text("Production Rules.")
#move(10,137)
#text("_________________")
#move(30,160)
#text("The system allows production rules to be used in conjunction with the")
#move(10,180)
#text("run string to produce a more complex string which turtle then executes.")
#move(30,200)
#text("A production rule is of the form:")
#move(50,240)
#text("A=STRING")
#move(10,280)
#text("where a is an alphabetic character and STRING is a string of characters.")
#move(10,300)
#text("The rule means that if the character A exists in the run string, it will")
#move(10,320)
#text("be expanded to STRING.")
#move(30,340)
#text("For example, given the string:")
#move(50,370)
#text("F+C--X+CF")
#move(10,400)
#text("and the production rule:")
#move(50,430)
#text("C=GBT")
#move(10,460)
#text("the string is expanded to:")
#move(50,490)
#text("F+GBT--X+GBTF")
#wait(180)

#cls(1)
#setpen(2)
#move(30,95)
#text("For an example, let's look at the Koch curve.")
#move(30,135)
#text("This is produced by the production rule:")
#move(50,175)
#text("F=F-F++F-F")
#move(30,215)
#text("And the statement:")
#move(50,255)
#text("#run(F)")
#move(30,285)
#text("The following screen shows successive expansions of the initial string")
#move(10,315)
#text("(F) from no expansion to 3 expansions. The turning angle is 60.")
#wait(180)  

#cls(1)
#setpen(2)
#move(8,60)
#text("Level  String                                Result")
#set_heading(90)
#set_length(600)
#move(8,64)
#run(F)
#set_heading(0)
#move(50,500)
#run(F)
#move(360,500)
#run(F)
#move(18,140)
#text("0")
#move(60,140)
#text("F")
#move(18,220)
#text("1")
#move(60,220)
#text("F-F++F-F")
#move(18,300)
#text("2")
#move(60,300)
#text("F-F++F-F-F-F++F-F++F-F++F-F-F-F++F-F")
#move(18,380)
#text("3")
#move(60,380)
#text("F-F++F-F-F-F++F-F++F-F++F-F-F-F++F-F")
#move(60,400)
#text("-F-F++F-F-F-F++F-F++F-F++F-F-F-F++F-F")
#move(60,420)
#text("F-F++F-F-F-F++F-F++F-F++F-F-F-F++F-F")
#move(56,440)
#text("++F-F++F-F-F-F++F-F++F-F++F-F-F-F++F-F")
#setpen(5)
#set_angle(60)
#move(370,140)
F=F-F++F-F
#set_heading(90)
#set_length(189)
#set_level(0)
#run(F)
#move(370,220)
#set_length(63)
#set_level(1)
#run(F)
#move(370,300)
#set_length(21)
#set_level(2)
#run(F)
#move(370,380)
#set_length(7)
#set_level(3)
#run(F)
#wait( 120)

#cls(1)
#setpen(2)
#move(30,80)
#text("Level 5:")
#move(30,82)
#text("________")
#setpen(5)
#move(40,240)
#set_length(2)
#set_level(5)
F=F-F++F-F
#run(F)
#setpen(2)
#move(50,480)
#text("The level is controlled by #set_level(LEVEL).")
#wait(180)

#cls(1)
#setpen(2)
#move(30,95)
#text("Other characters can be used in the production rules and initial")
#move(10,115)
#text("string. For example, the production rules for the dragon curve are:")
#move(70,145)
#text("X = X+YF+")
#move(70,165)
#text("Y = -FX-Y")
#move(30,195)
#text("The run statement is #run(X). The X and Y are expanded as normal,")
#move(30,215)
#text("but are ignored in the final string.")
#move(30,275)
#text("The following screen shows successive expansions of the initial string")
#move(10,295)
#text("(X) from no expansion to 3 expansions. The turning angle is 90.")
#wait(180)  

#cls(1)
#setpen(2)
F=
#move(8,60)
#text("Level  String                                Result")
#set_heading(90)
#set_length(600)
#move(8,64)
#run(F)
#set_heading(0)
#move(50,500)
#run(F)
#move(360,500)
#run(F)
#move(18,140)
#text("0")
#move(60,140)
#text("X")
#move(18,220)
#text("1")
#move(60,220)
#text("X+YF+")
#move(18,300)
#text("2")
#move(60,300)
#text("X+YF+-FX-YF+")
#move(18,380)
#text("3")
#move(60,380)
#text("X+YF++-FX-YF+-FX+YF+--FX-YF+")
#setpen(7)
#set_angle(90)
#move(400,140)
X=X+YF+
Y=-FX-Y
#set_heading(0)
#set_length(80)
#set_level(0)
#run(X)
#move(400,220)
#set_length(80)
#set_level(1)
#run(X)
#move(480,300)
#set_length(40)
#set_level(2)
#run(X)
#move(400,380)
#set_length(20)
#set_level(3)
#run(X)
#wait(180)

#cls(1)
#setpen(2)
#move(30,80)
#text("Level 8:")
#move(30,82)
#text("________")
#setpen(5)
#move(380,340)
#set_length(8)
#set_level(11)
#run(X)
#wait(180)

#cls(1)
#setpen(2)
#move(30,80)
#text("That's about it. The run files, such as this file and the demo file")
#move(10,100)
#text("can be created or edited using a text editor, which can be invoked")
#move(10,120)
#text("by selecting the Files/Edit menu.")
#move(30,150)
#text("To rerun this tutorial, choose the Files/Rerun menu.")
#move(30,180)
#text("To run another file, choose the Files/Run menu.")
#move(30,210)
#text("To quit, choose the Project/Quit menu.")
#move(300,256)
#text("**END**")