Drawing planets: PL9

       Name: PL9                                                     [Show more]
       Type: Subroutine
   Category: Drawing planets
    Summary: Draw the planet as a plain circle
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * PLANET calls PL9


 Draw the planet with radius K at pixel coordinate (K3, K4).


 Arguments:

   K(1 0)               The planet's radius

   K3(1 0)              Pixel x-coordinate of the centre of the planet

   K4(1 0)              Pixel y-coordinate of the centre of the planet

   INWK                 The planet's ship data block


.PL9

 JSR WPLS2              ; Call WPLS2 to remove the planet from the screen

 JMP CIRCLE             ; Call CIRCLE to draw the planet's new circle, returning
                        ; from the subroutine using a tail call

;BCS PL20               ; These instructions are commented out in the original
;                       ; source, as the Apple II version only has circles for
;LDA K+1                ; planets, with no meridians or craters
;BEQ PL25
;
;.PL20
;
;RTS