1 files changed, 58 insertions, 0 deletions
diff --git a/go/game/range.go b/go/game/range.go
new file mode 100644
index 00000000..ab86c44e
--- /dev/null
+++ b/go/game/range.go
@@ -0,0 +1,58 @@
+package game
+
+import (
+	"math"
+)
+
+func IsPositionInRange(origin Position, pos Position, r int) bool {
+	x, y := float64(pos.X-origin.X), float64(pos.Y-origin.Y)
+	ax, ay := math.Abs(x), math.Abs(y)
+	if ax > float64(r) || ay > float64(r) {
+		return false
+	}
+
+	var abs float64
+	if pos.X > pos.Y {
+		abs = ax + math.Floor(ay/2)
+	} else {
+		abs = ay + math.Floor(ax/2)
+	}
+
+	return abs <= float64(r)
+}
+
+func PositionsInRange(origin Position, r int, includeOrigin bool) []Position {
+	positions := []Position{}
+	for x := -r; x <= r; x++ {
+		for y := -r; y <= r; y++ {
+			pos := Position{origin.X + x, origin.Y + y}
+			if pos.X < 0 || pos.Y < 0 {
+				continue
+			}
+
+			if !includeOrigin && pos == origin {
+				continue
+			}
+
+			if IsPositionInRange(origin, pos, r) {
+				positions = append(positions, pos)
+			}
+		}
+	}
+	return positions
+}
+
+func TilesInRangeFromOrigin(m *Map, origin Position, r int) []*Tile {
+	tiles := []*Tile{}
+	for _, pos := range PositionsInRange(origin, r, false) {
+		tile := m.TileAt(pos)
+		if tile != nil {
+			tiles = append(tiles, tile)
+		}
+	}
+	return tiles
+}
+
+func TilesInRange(m *Map, p Permanent, r int) []*Tile {
+	return TilesInRangeFromOrigin(m, p.Tile().Position, r)
+}