Drawing circles: CIRCLE, Removed

       Name: CIRCLE, Removed                                         [Show more]
       Type: Subroutine
   Category: Drawing circles
    Summary: Draw a circle for the planet
  Deep dive: Drawing circles
    Context: See this subroutine in context in the source code
 References: No direct references to this subroutine in this source file


 Draw a circle with the centre at (K3, K4) and radius K. Used to draw the
 planet's main outline.


 Arguments:

   K                    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


                        \ --- Mod: Code removed for Elite-A: ------------------>

\.CIRCLE
\
\ LDA #0                \ Set LSX2 = 0 to indicate that the ball line heap is
\ STA LSX2              \ not empty, as we are about to fill it
\
\ LDX K                 \ Set X = K = radius
\
\ LDA #8                \ Set A = 8
\
\ CPX #8                \ If the radius < 8, skip to PL89
\ BCC PL89
\
\ LSR A                 \ Halve A so A = 4
\
\ CPX #60               \ If the radius < 60, skip to PL89
\ BCC PL89
\
\ LSR A                 \ Halve A so A = 2
\
\.PL89
\
\ STA STP               \ Set STP = A. STP is the step size for the circle, so
\                       \ the above sets a smaller step size for bigger circles
\
\                       \ Fall through into CIRCLE2 to draw the circle with the
\                       \ correct step size

                        \ --- End of removed code ----------------------------->