OPENTTD_SPRITES_COUNT = 112, // number of gfx-sprites in openttd.grf
SPR_SIGNALS_BASE = 4896,
SPR_CANALS_BASE = SPR_SIGNALS_BASE + 486,
SPR_SLOPES_BASE = SPR_CANALS_BASE + 70,
SPR_SLOPES_BASE = SPR_CANALS_BASE + 70,
SPR_SLOPES_INCLINED_OFFSET = 15,
SPR_SLOPES_VIRTUAL_BASE = SPR_SLOPES_BASE - SPR_SLOPES_INCLINED_OFFSET, // The original foundations (see SPR_FOUNDATION_BASE below) are mapped before the additional foundations.
SPR_SLOPES_NO_FOUNDATION_NW_OFFSET = 22, // no wall on the NW edge of the tile.
SPR_SLOPES_NO_FOUNDATION_NE_OFFSET = 44, // no wall on the NE edge of the tile.