Simple Spatial Hash in Go

spatialhash.go

package path

type SpatialHash struct {
	CellSize float64
	Cells    map[SpatialHashKey][]interface{}
}

type SpatialHashKey struct {
	X, Y int
}

func NewSpatialHash(cellSize float64) *SpatialHash {
	cells := make(map[SpatialHashKey][]interface{})
	return &SpatialHash{cellSize, cells}
}

func (h *SpatialHash) KeyForPoint(point Vector) SpatialHashKey {
	x := Round(point.X / h.CellSize)
	y := Round(point.Y / h.CellSize)
	return SpatialHashKey{x, y}
}

func (h *SpatialHash) Add(point Vector, data interface{}) {
	key := h.KeyForPoint(point)
	h.Cells[key] = append(h.Cells[key], data)
}

func (h *SpatialHash) Nearby(point Vector) []interface{} {
	var result []interface{}
	key := h.KeyForPoint(point)
	for dx := -1; dx <= 1; dx++ {
		for dy := -1; dy <= 1; dy++ {
			k := SpatialHashKey{key.X + dx, key.Y + dy}
			result = append(result, h.Cells[k]...)
		}
	}
	return result
}