Bounds

IBound is a generalization of the idea of a bounding box to different sorts of grids.

A bound represents a collection of cells using a small class, which typically stores the min and max extents of the cells. Bounds cannot represent an exact arbitrary collection of cells, for that, you should use a HashSet<Cell>. So bounds are best used in cases where it doesn't matter if a few too many cells are included, such as in many chunking and culling algorithms.

Not all grids support bounds. The ones that don't will simply return null, which represents bounds that cover the entire grid. When grids do support bounds, the specific class that grid uses is documented with the grid. The classes are usually named similarly: SquareGrid uses SquareBound, HexGrid uses HexBound and so on.

Working with bounds

IGrid has many methods for working with bounds. Probably the most important are

GetBound

Finds the smallest bound that contains all the given cells

GetCellsInBounds

Finds all the cells inside a bound

IsCellInBound

Tests if a given cell is inside a bound.

IntersectBounds/UnionBounds

Combines two bounds into one.

Most of these methods will also accept a null bound, meaning the entire grid.

If you know the specific class of a bound, you can use that type instead of IBound. Most bounds have useful methods and constructors on them, and implement IEnumerable<Cell> to easily get the cells within.

Bounded grids

Grids themselves often are associated with a specific bound. For example, new SquareGrid(1) gives an infinite grid of squares. But you can restrict the grid:

var infiniteGrid = new SquareGrid(1);
var bound = new SquareBound(new Vector2Int(0,0), new Vector2Int(8,8));
var grid = infiniteGrid.BoundBy(bound);

The new grid returned only contains cells in the range 0 <= x < 8 and 0 <= y < 8, like the 64 cells of a chess board. All grid methods, like TryMove or GetCells will respect this bound and not return cells outside the bound.

To remove the bound from a grid, you can access grid.Unbounded.

Note

To restrict a grid to a set of cells not representable by a bound, use MaskModifier.