Types of Contiguity[]
When a tile touches another tile, it is said to be contiguous. There are two types of contiguity that can occur on square-tile maps. There is adjacency which is called ADJACENT, and then there is cardinal adjacency, referred to as CARDINALLY ADJACENT.
These two types of tile contiguity are not the same: all cardinally adjacent tiles are also adjacent. But not all adjacent tiles are cardinally adjacent. This is clarified in the diagrams below.
Adjacency[]
Adjacent tiles are any of the 8 tiles that touch the tile in question. Adjacent tiles may also be referred to as 8-adjacent. In the image below:
- The blue tile is the tile in question.
- The green tiles are adjacent.
- White tiles are non-adjacent.
adjacent
Cardinal Adjacency[]
Cardinally Adjacent tiles are the 4 tiles that directly touch the tile in question, not including the corners. Cardinal Adjacency gets its name from the "four cardinal directions" of North, South, East, and West. In the image below:
- The blue tile is the tile in question.
- The green tiles are cardinally adjacent.
- White tiles are not cardinally-adjacent.
cardinally adjacent
Diagonal Adjacency[]
Diagonally adjacent tiles touch a given tile diagonally. This is just an easier way to say "adjacent tiles which don't qualify as cardinally adjacent."
In the image below:
- The blue tile is the tile in question.
- The green tiles are diagonally adjacent.
- White tiles are not diagonally adjacent.
diagonally adjacent
Hex Adjacency[]
On hexagonal maps, the geometry doesn't differentiate between adjacency and cardinal adjacency. There is only one kind of adjacency. Therefore, on hex maps, rules for adjacency and cardinal adjacency are treated the same. That is, adjacency and cardinal adjacency are synonymous and any rule for one or the other is treated the same, when playing on a hex map. In the image below:
- The blue tile is the tile in question.
- The green tiles are adjacent, and will qualify as cardinally adjacent also.
- The white tiles are non-adjacent, and will not qualify as cardinally adjacent either.
adjacent