Drawing the landscape: DrawFlatTile

       Name: DrawFlatTile                                            [Show more]
       Type: Subroutine
   Category: Drawing the landscape
    Summary: Draw a flat tile in the correct colour for the chess board effect
             that we use to draw the landscape
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * DrawLandscapeView (Part 3 of 3) calls DrawFlatTile
             * DrawTileAndObjects calls DrawFlatTile


.DrawFlatTile

 LDX #0                 \ If bit 0 of xTileToDraw and zTile are the same, then
 LDA xTileToDraw        \ the tile's x-coordinate and z-coordinate are either
 EOR zTile              \ both odd or both even, so jump to DrawOneFaceTile
 AND #1                 \ with X set to 0 to draw this tile in colour 3 (white,
 BEQ DrawOneFaceTile    \ yellow, cyan or red)

 LDX #8                 \ Otherwise the tile's x-coordinate and z-coordinate are
                        \ different (i.e. one is odd and one is even), so set
                        \ X to 8 to draw this tile in colour 0 (blue)

                        \ We now have a very short interlude to set the value of
                        \ stashOffset as part of the game's anti-cracker code,
                        \ and we pick up the tile-drawing process again in the
                        \ DrawOneFaceTile routine