Extra tracks: HookFixHorizon

       Name: HookFixHorizon                                          [Show more]
       Type: Subroutine
   Category: Extra tracks
    Summary: Apply the horizon line in A instead of horizonLine
  Deep dive: Secrets of the extra tracks
             Code hooks in the extra tracks
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * newContentHi calls HookFixHorizon
             * newContentLo calls HookFixHorizon


 This routine is called from GetTrackAndMarkers to cut objects off at the track
 line in A rather than horizonLine.


 Arguments:

   A                    The updated value of horizonLine

   Y                    The horizon section index in the verge buffer from
                        horizonListIndex


.HookFixHorizon

 STA &1FEA              \ Modify the DrawObject routine at dobj3 instruction #6
                        \ so that objects get cut off at the track line number
                        \ in A instead of horizonLine when they are hidden
                        \ behind a hill

 STA yVergeLeft,Y       \ Set the pitch angle for the left side of the horizon
                        \ line in the track verge buffer to the updated value of
                        \ horizonLine (this is the instruction that we overwrote
                        \ with the call to the hook routine, so this makes sure
                        \ we still do this)

 RTS                    \ Return from the subroutine