Screen buffer: DrawTrackLine (Part 2 of 2)

       Name: DrawTrackLine (Part 2 of 2)                             [Show more]
       Type: Subroutine
   Category: Screen buffer
    Summary: Draw a pixel line across the screen in the track view
  Deep dive: Drawing around the dashboard
             Drawing the track view
    Context: See this subroutine in context in the source code
 References: No direct references to this subroutine in this source file


.prow2

                        \ At this point, X contains the offset within the dash
                        \ data of the pixel line to be drawn across the screen

 LDA backgroundColour,X \ Fetch the colour of the first byte on the line from
 AND #%00000011         \ the X-th entry in backgroundColour (bits 0 to 2)
 TAY

 LDA colourPalette,Y    \ Set A to logical colour Y from the colour palette,
                        \ to use as the first byte on the line

                        \ Fall through into DrawTrackBytes to draw the pixel
                        \ bytes that make up the line we want to draw
                        \
                        \ If we are drawing the lines above the top of the
                        \ dashboard, then the following then loops back to the
                        \ start of the DrawTrackLine routine to keep drawing
                        \ lines until we do reach the top of the dashboard, at
                        \ which point we return from the DrawTrackLine routine
                        \ to part 2 of DrawTrackView, which modifies the code to
                        \ draw subsequent lines around the shape of the
                        \ dashboard