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(**************************************************************************)
(* *)
(* MPG - Graphik - System *)
(* *)
(* Version 2.1 vom 10.09.1987 *)
(* *)
(* (c) 1987 Beat Jegerlehner & Carsten Weinholz *)
(* unter Verwendung der Standard-Graphik *)
(* "Turtle-Graphik" geschrieben von B.Jegerlehner *)
(* *)
(**************************************************************************)
(* *)
(* Dieses Paket stellt eine LOGO-aehnliche *)
(* 'Schildkroetengraphik' zur Verfuegung *)
(* *)
(**************************************************************************)
PACKET turtle graphics DEFINES begin turtle,
end turtle,
forward ,
forward to ,
turn ,
turn to ,
pen up ,
pen down ,
pen ,
angle ,
get turtle :
REAL VAR x pos,
y pos,
winkel;
PICFILE VAR bild;
PICTURE VAR pic;
BOOL VAR direct,
pen status;
PROC begin turtle:
direct := TRUE;
x pos := 0.0;
y pos := 0.0;
winkel := 0.0;
begin plot;
clear;
viewport (0.0, 1.0, 0.0, 1.0);
window (-500.0, 500.0, -500.0, 500.0);
pen up;
forward to (0.0, 0.0)
END PROC begin turtle;
PROC begin turtle (TEXT CONST picfile):
direct := FALSE;
bild := picture file (picfile);
pic := nilpicture;
x pos := 0.0;
y pos := 0.0;
winkel := 0.0;
pen up;
forward to (0.0,0.0)
END PROC begin turtle;
PROC end turtle:
IF direct
THEN end plot
ELSE ausgabe
FI.
ausgabe:
REAL VAR x cm,y cm;
INT VAR dummy;
put picture (bild,pic);
drawing area (x cm,y cm,dummy,dummy);
viewport (bild, 0.0, 1.0, 0.0, 1.0);
window (bild, -500.0,500.0,-500.0,500.0);
plot(bild)
END PROC end turtle;
PROC turn (REAL CONST w):
winkel := (winkel + w) MOD 360.0
END PROC turn;
PROC turn to (REAL CONST w):
winkel := w MOD 360.0
END PROC turn to;
REAL PROC angle:
winkel
END PROC angle;
PROC forward (REAL CONST len):
forward to (x pos + cosd (winkel) * len,
y pos + sind (winkel) * len)
END PROC forward;
PROC pen up:
pen status := FALSE
END PROC pen up;
PROC pen down:
pen status := TRUE
END PROC pen down;
BOOL PROC pen:
pen status
END PROC pen;
PROC forward to (REAL CONST x,y):
IF direct
THEN dir plot
ELSE pic plot
FI;
x pos := x;
y pos := y.
dir plot:
IF pen status
THEN draw (x,y)
ELSE move (x,y)
FI.
pic plot:
IF length (pic) > 1923
THEN put picture (bild,pic);
pic := nilpicture
FI;
IF pen status
THEN draw (pic,x,y)
ELSE move (pic,x,y)
FI
END PROC forward to;
PROC get turtle (REAL VAR x,y):
x := x pos;
y := y pos
END PROC get turtle
END PACKET turtle graphics
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