Antic Magazine 1982 August/Antic_August_1982_Vol_1_No_3.atr/fort0882.txt

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(    Turtle Graphics I, screen 1          )¢¢DECIMAL¢¢TABLE SINES¢0000 , 0175 , 0349 , 0523 , 0698 ,¢0872 , 1045 , 1219 , 1392 , 1564 ,¢1736 , 1908 , 2079 , 2250 , 2419 ,¢2588 , 2756 , 2924 , 3090 , 3256 ,¢3420 , 3584 , 3746 , 3907 , 4067 ,¢4226 , 4384 , 4540 , 4695 , 4848 ,¢5000 , 5150 , 5299 , 5446 , 5592 ,¢5736 , 5878 , 6018 , 6157 , 6293 ,¢6428 , 6561 , 6691 , 6820 , 6947 ,¢7071 , 7193 , 7314 , 7431 , 7547 ,¢7660 , 7771 , 7880 , 7986 , 8090 ,¢8192 , 8290 , 8387 , 8480 , 8572 ,¢8660 , 8746 , 8829 , 8910 , 8988 ,¢9063 , 9135 , 9205 , 9272 , 9336 ,¢9397 , 9455 , 9511 , 9563 , 9613 ,¢9659 , 9703 , 9744 , 9781 , 9816 ,¢9848 , 9877 , 9903 , 9925 , 9945 ,¢9962 , 9976 , 9986 , 9994 , 9998 ,¢10000 , -->¢¢¢(    Turtle Graphics I, screen 2       )¢¢: (SIN)    ( n1 --- n2 )¢      DUP 90 > IF¢  180 SWAP - THEN¢            SINES ;¢¢: SIN      ( n1 --- n2 )¢  ( Returns 10000 times the sine )¢  ( of n1 degrees. )¢                 360 MOD¢              DUP 0< IF¢            360 + THEN¢          DUP 180 > IF¢  180 - (SIN) MINUS ELSE¢              (SIN) THEN ;¢¢: COS    ( n1 --- n2 )¢  ( Returns 10000 times the cosine )¢  ( of n1 degrees. )¢  360 MOD   90 + SIN ;¢¢-->¢¢¢( 32 Turtle Graphics I, screen 3       )¢: SIN*   ( n1 n2 --- n3 )¢  ( Returns n1 times the sine of )¢  ( n2 degrees. )¢  SIN 10000 */ ;¢¢: COS*   ( n1 n2 --- n3 )¢  ( Returns n1 times the cosine of )¢  ( n2 degrees. )¢  COS 10000 */ ;¢¢-->¢¢¢( 33 Turtle Graphics I, screen 4a      )¢¢0 VARIABLE TO-FLAG¢¢CODE TO   ( --- )¢  1 # LDA, TO-FLAG STA,¢      NEXT JMP, END-CODE¢¢: VALUE¢                         0 CONSTANT¢                              ;CODE¢              TO-FLAG LDA, 0= IF,¢         2 # LDY, W )Y LDA, PHA,¢  INY, W )Y LDA, PUSH JMP, ELSE,¢          0 # LDA, TO-FLAG STA,¢   BOT LDA, 2 # LDA, W )Y STA,¢    BOT 1+ LDA, INY, W )Y STA,¢                 POP JMP, THEN,¢                      END-CODE¢¢-->¢¢¢( 34 Turtle Graphics I, screen 4b      )¢¢0 VARIABLE TO-FLAG¢¢: TO¢  1 TO-FLAG ! ;¢¢: VALUE¢          <BUILDS 0 ,¢  DOES> TO-FLAG @ IF¢        0 TO-FLAG !¢             !   ELSE¢             @   THEN ;¢¢¢-->¢¢¢(    Turtle Graphics I, screen 5      )¢¢VOCABULARY CLIPPING  IMMEDIATE¢¢CLIPPING DEFINITIONS¢¢VALUE LEFT          VALUE TOP¢VALUE RIGHT         VALUE BOTTOM¢¢2 BASE !¢¢: CODE    ( p --- n )¢                         0¢             OVER TOP < IF¢     1000 + SWAP DROP ELSE¢          SWAP BOTTOM > IF¢               0100 + THEN¢                       THEN¢             OVER LEFT < IF¢     0001 + SWAP DROP ELSE¢          SWAP RIGHT > IF¢               0010 + THEN¢                       THEN ;¢-->¢¢(    Turtle Graphics I, screen 6       )¢¢VALUE X1¢VALUE Y1¢VALUE C1¢VALUE X2¢VALUE Y2¢VALUE C2¢VALUE C¢¢: CLIP_X    ( n1 --- n2 )¢      Y1 _¢   X2 X1 _¢   Y2 Y1 _¢  */  X1 +;¢¢: CLIP_y    ( n1 --- n2 )¢      X1 _¢   Y2 Y1 _¢   X2 X1 _¢  */  Y1 +;¢¢-->¢¢¢( 37 Turtle Graphics I, screen 7        )¢¢2 BASE !¢¢: WHERE?    ( --- p )¢                     C 0001 AND IF¢           LEFT LEFT CLIP_Y ELSE¢                   C 0010 AND IF¢           RIGHT  RIGHT CLIP_Y  ELSE¢                   C 0100 AND IF¢       BOTTOM CLIP_X  BOTTOM ELSE¢                    C 1000 AND IF¢            TOP CLIP_X  TOP  THEN¢                              THEN¢                               THEN¢                                THEN ;¢DECIMAL¢¢: HERE!   ( p --- )¢                                C C1 = IF¢  TO Y1  TO X1  X1 Y1 CODE TO C1  ELSE¢  TO Y2  TO X2  X2 Y2 CODE TO C2  THEN ;¢¢-->¢¢¢( 38 Turtle Graphics I, screen 8       )¢¢FORTH DEFINITIONS¢¢: CLIP    ( p1 p2 --- p1' p2' t )¢          (       or            )¢          ( p1 p2 --- f         )¢                           CLIPPING¢   TO Y2   TO X2  X2 Y2 CODE TO C2¢   TO Y1   TO X1  X1 Y1 CODE TO C1¢                             BEGIN¢                    C1 C2 OR WHILE¢                     C1 C2 AND IF¢                        0 ;S THEN¢                            C1 IF¢                     C1 TO C ELSE¢                     C2 TO C THEN¢               WHERE? HERE! REPEAT¢                     X1 Y1 X2 Y2 1 ;¢¢-->¢¢¢( 39 Turtle Graphics I, screen 9       )¢¢: GRAPHICS    ( n --- )¢   ( Clears the screen and sets it up )¢   ( for graphics mode n with a text )¢   ( window. )¢   >R    SETUP S   CLOSE S¢    SPLIT-SCREEN    R> GR. ;¢¢: LINE    ( p1 p2 --- )¢   ( Displays whatever piece of the )¢   ( line from p1 to p2 is within )¢   ( the clipping window. )¢        CL# @ COLOR¢            CLIP IF¢   PLOT DRAWTO THEN ;¢¢;S¢