Dashboard: DOT

       Name: DOT                                                     [Show more]
       Type: Subroutine
   Category: Dashboard
    Summary: Draw a dash on the compass
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * COMPAS calls DOT
             * SP2 calls DOT


 Arguments:

   COMX                 The screen pixel x-coordinate of the dash

   COMY                 The screen pixel y-coordinate of the dash

   COMC                 The colour and thickness of the dash:

                          * #YELLOW = a double-height dash in yellow, for when
                            the object in the compass is in front of us

                          * #GREEN = a single-height dash in green, for when
                            the object in the compass is behind us


.DOT

 LDA COMY               ; Set Y1 = COMY, the y-coordinate of the dash
 STA Y1

 LDA COMX               ; Set X1 = COMX, the x-coordinate of the dash
 STA X1

 LDA COMC               ; Set COL = COMC, the mode 5 colour byte for the dash
 STA COL

 CMP #YELLOW            ; If the dash's colour is not yellow, jump to CPIX2 to
 BNE CPIX2              ; draw a single-height dash in the compass, as it is
                        ; showing that the planet or station is behind us

                        ; Otherwise the dash is yellow, which is in front of us,
                        ; so fall through into CPIX4 to draw a double-height
                        ; dash in the compass