Internal Picture Definition ☆
An internal picture definition is one of internal procedures, and is functionally the same as an internal subprogram.
An internal picture definition is written within a program unit.
An internal picture definition begins with a PICTURE line and ends with a END-PICTURE line.
Example 3. An internal picture
100 OPTION ANGLE DEGREES 110 SET WINDOW -4,4,-4,4 120 DRAW polygon(6) 130 DRAW polygon(7) WITH ROTATE(-90/7)*SCALE(1.5)*SHIFT(2,2) 140 PICTURE polygon(n) 150 FOR i=0 TO n 160 PLOT LINES:COS(i*360/n),SIN(i*360/n); 170 NEXT i 180 END PICTURE 190 END
The main program consists of the whole lines.
Among these lines, lines 140 to 180 make up an internal picture.
A feature of internal picture definitions
All variables except parameters are shared with the program unit.
For example, on the following program, variable i in lines 120 to 140 and variable i in lines 170 to 190 are identical. Therefore, Because the variable i changes when the DRAW statement in 130-line is executed, the FOR～NEXT loop in lines 120 to 140 does not work correctly.
100 OPTION ANGLE DEGREES 110 SET WINDOW -4,4,-4,4 120 FOR i=-4 to 4 130 DRAW polygon(7) WITH SHIFT(i,i) 140 NEXT i 150 PICTURE polygon(n) 170 FOR i=0 TO n 180 PLOT LINES:COS(i*360/n),SIN(i*360/n); 190 NEXT i 200 END PICTURE 210 END