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Diffstat (limited to 'ipl/gprocs/subturtl.icn')
| -rw-r--r-- | ipl/gprocs/subturtl.icn | 275 |
1 files changed, 275 insertions, 0 deletions
diff --git a/ipl/gprocs/subturtl.icn b/ipl/gprocs/subturtl.icn new file mode 100644 index 0000000..6464eb1 --- /dev/null +++ b/ipl/gprocs/subturtl.icn @@ -0,0 +1,275 @@ +############################################################################ +# +# File: subturtl.icn +# +# Subject: Procedures for turtle-graphics (subset version) +# +# Author: Gregg M. Townsend +# +# Date: January 30, 1996 +# +############################################################################ +# +# This file is in the public domain. +# +############################################################################ +# +# These procedures implement a simplified subset of the turtle.icn +# package. The main omissions are scaling, TWindow(), THome(), and +# high-level primitives like TCircle(). Some procedures accept fewer +# arguments, omit defaults, or omit the return value. +# +############################################################################ +# +# The procedures are as follows: +# +# TDraw(n) -- move forward and draw +# TSkip(n) -- skip forward without drawing +# The turtle moves forward n units. n can be negative to move +# backwards. +# +# TDrawto(x, y) -- draw to the point (x,y) +# The turtle turns and draws a line to the point (x,y). +# The heading is also set as a consequence of this movement. +# +# TGoto(x, y) -- set location +# The turtle moves to the point (x,y) without drawing. +# The turtle's heading remains unaltered. +# +# TRight(d) -- turn right +# TLeft(d) -- turn left +# The turtle turns d degrees to the right or left of its current +# heading. Its location does not change, and nothing is drawn. +# +# TFace(x, y) -- set heading +# The turtle turns to face directly to face the point (x,y). +# If the turtle is already at (x,y), the heading does not change. +# +# TX() -- query current x position +# TY() -- query current y position +# The x- or y-coordinate of the turtle's current location is +# returned. +# +# THeading() -- query heading +# The turtle's heading (in degrees) is returned. +# +# TSave() -- save turtle state +# TRestore() -- restore turtle state +# TSave saves the current turtle window, location, and heading +# on an internal stack. TRestore pops the stack and sets +# those values, or fails if the stack is empty. +# +# TReset() -- clear screen and reinitialize +# The window is cleared, the turtle moves to the center of the +# screen without drawing, the heading is set to -90 degrees, and +# the TRestore() stack is cleared. These actions restore the +# initial conditions. +# +############################################################################ +# +# Links: graphics +# +############################################################################ +# +# Requires: Version 9 graphics +# +############################################################################ +# +# See also: turtle.icn +# +############################################################################ + +link graphics + +global T_x, T_y # current location +global T_deg # current heading +global T_stack # turtle state stack + + +# TInit() -- initialize turtle system, opening window if needed + +procedure TInit() #: initialize turtle system + + initial { + if /&window then + WOpen("width=500", "height=500") | stop("can't open window") + T_stack := [] + T_x := WAttrib("width") / 2 + 0.5 + T_y := WAttrib("height") / 2 + 0.5 + T_deg := -90.0 + } + + return + +end + + +# TReset() -- clear screen and stack, go to center, head -90 degrees + +procedure TReset() #: reset turtle system + initial TInit() + + EraseArea() + T_stack := [] + T_x := WAttrib("width") / 2 + 0.5 + T_y := WAttrib("height") / 2 + 0.5 + T_deg := -90.0 + + return + +end + + +# TDraw(n) -- move forward n units while drawing a line + +procedure TDraw(n) #: draw with turtle + local rad, x, y + initial TInit() + + rad := dtor(T_deg) + x := T_x + n * cos(rad) + y := T_y + n * sin(rad) + DrawLine(T_x, T_y, x, y) + T_x := x + T_y := y + + return + +end + + +# TDrawto(x, y) -- draw line to (x,y) + +procedure TDrawto(x, y) #: draw to with turtle + initial TInit() + + TFace(x, y) + DrawLine(T_x, T_y, x, y) + T_x := x + T_y := y + + return + +end + + +# TSkip(n) -- move forward n units without drawing + +procedure TSkip(n) #: skip with turtle + local rad + initial TInit() + + rad := dtor(T_deg) + T_x +:= n * cos(rad) + T_y +:= n * sin(rad) + + return + +end + + +# TGoto(x, y) -- move to (x,y) without drawing + +procedure TGoto(x, y) #: goto with turtle + initial TInit() + T_x := x + T_y := y + + return + +end + + +# TRight(d) -- turn right d degrees + +procedure TRight(d) #: turn turtle right + initial TInit() + + T_deg +:= d + T_deg %:= 360 # normalize + + return + +end + + +# TLeft(d) -- turn left d degrees + +procedure TLeft(d) #: turn turtle left + initial TInit() + + T_deg -:= d + T_deg %:= 360 # normalize + + return + +end + + +# TFace(x, y) -- turn to face (x,y), unless already there + +procedure TFace(x, y) #: turn turtle to face point + initial TInit() + + if x ~= T_x | y ~= T_y then + T_deg := rtod(atan(y - T_y, x - T_x)) + + return + +end + + +# TX() -- return current x location + +procedure TX(x) #: turtle x coordinate + initial TInit() + + return T_x + +end + + +# TY() -- return current y location + +procedure TY(y) #: turtle y coordinate + initial TInit() + + return T_y + +end + + +# THeading() -- return current heading + +procedure THeading() #: turtle heading + initial TInit() + + return T_deg + +end + + +# TSave() -- save turtle state + +procedure TSave() #: save turtle state + initial TInit() + + push(T_stack, T_deg, T_y, T_x) + + return + +end + + +# TRestore() -- restore turtle state + +procedure TRestore() #: restore turtle state + initial TInit() + + T_x := pop(T_stack) + T_y := pop(T_stack) + T_deg := pop(T_stack) + + return + +end |