Universe: GTHG

       Name: GTHG                                                    [Show more]
       Type: Subroutine
   Category: Universe
    Summary: Spawn a Thargoid ship and a Thargon companion
  Deep dive: Fixing ship positions
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * MJP calls GTHG
             * Main game loop (Part 4 of 6) calls via GTHG+15


 Other entry points:

   GTHG+15              Spawn a lone Thargoid, without a Thargon companion and
                        with slightly less aggression than normal


.GTHG

 JSR Ze                 ; Call Ze to initialise INWK
                        ;
                        ; Note that because Ze uses the value of X returned by
                        ; DORND, and X contains the value of A returned by the
                        ; previous call to DORND, this does not set the new ship
                        ; to a totally random location. See the deep dive on
                        ; "Fixing ship positions" for details

 LDA #%11111111         ; Set the AI flag in byte #32 so that the ship has AI,
 STA INWK+32            ; is extremely and aggressively hostile, and has E.C.M.

 LDA #TGL               ; Call NWSHP to add a new Thargon ship to our local
 JSR NWSHP              ; bubble of universe

 JMP gthg1              ; Skip the following to add a Thargoid

                        ; We jump straight here if we call GTHG+15

 JSR Ze                 ; Call Ze to initialise INWK

 LDA #%11111001         ; Set the AI flag in byte #32 so that the ship has AI,
 STA INWK+32            ; is hostile and pretty aggressive (though not quite as
                        ; aggressive as the Thargoid we add if we get here via
                        ; GTHG), and has E.C.M.

.gthg1

 LDA #THG               ; Call NWSHP to add a new Thargoid ship to our local
 JMP NWSHP              ; bubble of universe, and return from the subroutine
                        ; using a tail call