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OpenTS Manual

CliffBackImpassability

Mode that turns a cell standing a cliff step below a neighbor into rock.

Specification
Applies to
global rules
File
rules.ini
Section
[General]
Value
integer
When omitted
0
rules.ini
[General]
CliffBackImpassability=2

CliffBackImpassability=2 turns a cell into Rock when a nearby cell stands at least a full cliff step, four height levels, above it. Movement costs and the buildable test then read Rock in place of the cell’s earlier land type.

Only 2 changes anything. 0 turns the rule off, and any other value runs the height test and ignores the result. The value is stored as a single signed byte, so a number outside -128 to 127 wraps before it is compared. For example, 258 acts as 2.

The test covers six cells, not the eight that surround the cell. Written as (x, y) offsets from the cell, it checks (0,-1), (-1,0), (+1,-1), (-1,+1) and (+1,+1), and also (+2,+2), two steps away. The cells at (+1,0), (0,+1) and (-1,-1) are never checked.

The rule is the last step in working out a cell’s land type, so it overrides the earlier steps. Whether it replaces the land type the cell has so far depends on where that land type came from:

  • An overlay whose land type is Wall or Railroad, or one set to NoUseTileLandType=yes: the cell becomes Rock whatever land type the overlay gave it.
  • A tile with no artwork for that part of the tile: the cell has already been reset to Clear, and it becomes Rock.
  • Any other cell: only Clear, Water, Beach and Ice become Rock. A cell that is already Road, Rough, Tiberium, Weeds, Tunnel, Wall or Railroad keeps its land type.
See also — Land, NoUseTileLandType