CLS
T_INIT
FOR K = 1 TO 180 STEP 15
FOR J = 0 TO 36000 STEP 360/K
CLS
T_PEN = 1
FOR N = 1 TO 200 
T_FD 5 + N
T_RT 15 + J/1000
T_FD 10 + N
T_RT J
NEXT N
T_PEN = 0
T_HOME
NEXT J
NEXT K
END

'::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
'GRAPH TURTLE 

'VARIABLES
'T_X : DISTANCE IN PIXELS
'T_Y : DISTANCE IN PIXELS
'T_DISTANCE : DISTANCE IN PIXELS
'T_PEN : 0 = PEN OFF   1 = PEN ON
'T_ANGLE : ANGLE IN DEGREES

SUB T_INIT
'INIT GRAPH TURTLE
T_W = XMAX
T_H = YMAX
T_CENTER_SCREEN_X = INT (T_W / 2)
T_CENTER_SCREEN_Y = INT (T_H / 2)
T_POSITION_X = T_CENTER_SCREEN_X
T_POSITION_Y = T_CENTER_SCREEN_Y
T_HEADING = 0
T_PEN = 1
END

SUB T_GT (T_X,T_Y)
'GO TO NEW POSITION X,Y PIXELS
T_NEW_POSITION_X = T_CENTER_SCREEN_X + T_X 
T_NEW_POSITION_Y = T_CENTER_SCREEN_Y + T_Y
IF T_PEN = 1 THEN LINE T_POSITION_X, T_POSITION_Y, T_NEW_POSITION_X, T_NEW_POSITION_Y
T_POSITION_X = T_NEW_POSITION_X
T_POSITION_Y = T_NEW_POSITION_Y 
END

SUB T_HOME
'GO HOME TURTLE
IF T_PEN = 1 THEN LINE T_POSITION_X, T_POSITION_Y, T_CENTER_SCREEN_X,T_CENTER_SCREEN_Y
T_POSITION_X  = INT(T_W/2)
T_POSITION_Y  = INT(T_H/2)
END

SUB T_FD (T_DISTANCE)
'FORWARD X DISTANCE PIXELES
T_NEW_POSITION_X = T_POSITION_X + (T_DISTANCE * SIN (T_HEADING))
T_NEW_POSITION_Y = T_POSITION_Y - (T_DISTANCE * COS (T_HEADING))
IF T_PEN = 1 THEN LINE T_POSITION_X, T_POSITION_Y, T_NEW_POSITION_X,T_NEW_POSITION_Y
T_POSITION_X = T_NEW_POSITION_X
T_POSITION_Y = T_NEW_POSITION_Y 
END

SUB T_BK(T_DISTANCE)
'BACK X DISTANCE PIXELES
T_NEW_POSITION_X = T_POSITION_X - ( T_DISTANCE * SIN (T_HEADING))
T_NEW_POSITION_Y = T_POSITION_Y + ( T_DISTANCE * COS (T_HEADING))
IF T_PEN = 1 THEN LINE T_POSITION_X, T_POSITION_Y, T_NEW_POSITION_X,T_NEW_POSITION_Y
T_POSITION_X = T_NEW_POSITION_X
T_POSITION_Y = T_NEW_POSITION_Y 
END

FUNC T_RT (T_ANGLE)
'TURN RIGHT, ANGLE DEGREES
T_HEADING = T_HEADING +  RAD (T_ANGLE)
END

FUNC T_LT (T_ANGLE) 
'TURN LEFT, ANGLE DEGREES
T_HEADING = T_HEADING - RAD (T_ANGLE)     
END

FUNC T_ORIENT (T_ANGLE)
'SET ORIENTATION TURTLE ANGLE DEGREES
T_HEADING = RAD (T_ANGLE)
END