The zTileMaxAltitude variable - The Sentinel on the BBC Micro

       Name: zTileMaxAltitude                                        [Show more]
       Type: Variable
   Category: Landscape
    Summary: The tile z-coordinate of the highest tile within each 4x4 block of
             tiles
    Context: See this variable in context in the source code
 References: This variable is used as follows:
             * AddEnemiesToTiles uses zTileMaxAltitude
             * GetHighestTiles uses zTileMaxAltitude


 This table stores the tile z-coordinate of the highest tile within each 4x4
 block of tiles in the landscape. It is only used while the landscape is being
 generated and the allocated memory is reused during gameplay.

 The table is laid out with one byte for each 4x4 block, starting in the
 front-left corner of the landscape at tile coordinate (0, 0), and moving along
 the front row from left to right, and then moving back by four tiles and
 moving that row from left to right, until we reach the rear row of 4x4 blocks.

 The rear row and rightmost column of blocks are one tile smaller, so they are
 4x3-tile and 3x4-tile blocks, with the far-right block being 3x3 tiles.

 You can picture this as partitioning the 31x31-tile landscape into an 8x8
 chess board, where each square on the chess board is made up of a 4x4 block of
 landscape tiles (and with smaller squares along the right and rear edges).


.zTileMaxAltitude

 EQUB &20, &20, &20, &53, &45, &43, &3A, &4A    \ These values are workspace
 EQUB &4D, &50, &20, &74, &61, &6B, &33, &0D    \ noise and have no meaning
 EQUB &14, &F0, &05, &20, &0D, &14, &FA, &05    \
 EQUB &20, &0D, &15, &04, &18, &2E, &74, &61    \ They actually contain snippets
 EQUB &6B, &31, &20, &54, &58, &41, &3A, &4A    \ of the original source code
 EQUB &53, &52, &20, &45, &4D, &49, &52, &50
 EQUB &54, &0D, &15, &0E, &05, &20, &0D, &15
 EQUB &18, &1F, &20, &20, &20, &20, &20, &20

 EQUB &4C, &44, &41, &20, &4F, &42, &54, &59    \ These bytes appear to be
 EQUB &50, &45, &2C, &58, &3A, &42, &4E, &45    \ unused
 EQUB &20, &74, &61, &6B, &34, &0D, &15, &22    \
 EQUB &05, &20, &0D, &15, &2C, &1E, &20, &5C    \ These values are workspace
                                                \ noise and have no meaning
                                                \
                                                \ They actually contain snippets
                                                \ of the original source code
Landscape: zTileMaxAltitude
