up3

server/block/cube/direction.go

@@ -0,0 +1,89 @@
+package cube
+
+// Direction represents a direction towards one of the horizontal axes
+type Direction int
+
+const (
+	// North represents the north direction, towards the negative Z.
+	North Direction = iota
+	// South represents the south direction, towards the positive Z.
+	South
+	// West represents the west direction, towards the negative X.
+	West
+	// East represents the east direction, towards the positive X.
+	East
+)
+
+// Face converts the direction to a Face and returns it.
+func (d Direction) Face() Face {
+	return Face(d + 2)
+}
+
+// Opposite returns Direction opposite to the current one.
+func (d Direction) Opposite() Direction {
+	switch d {
+	case North:
+		return South
+	case South:
+		return North
+	case West:
+		return East
+	case East:
+		return West
+	}
+	panic("invalid direction")
+}
+
+// RotateRight rotates the direction 90 degrees to the right horizontally
+// (clockwise) and returns the new direction.
+func (d Direction) RotateRight() Direction {
+	switch d {
+	case North:
+		return East
+	case East:
+		return South
+	case South:
+		return West
+	case West:
+		return North
+	}
+	panic("invalid direction")
+}
+
+// RotateLeft rotates the direction 90 degrees to the left horizontally
+// (counter-clockwise) and returns the new direction.
+func (d Direction) RotateLeft() Direction {
+	switch d {
+	case North:
+		return West
+	case East:
+		return North
+	case South:
+		return East
+	case West:
+		return South
+	}
+	panic("invalid direction")
+}
+
+// String returns the Direction as a string.
+func (d Direction) String() string {
+	switch d {
+	case North:
+		return "north"
+	case East:
+		return "east"
+	case South:
+		return "south"
+	case West:
+		return "west"
+	}
+	panic("invalid direction")
+}
+
+var directions = [...]Direction{North, East, South, West}
+
+// Directions returns a list of all directions, going from North to West.
+func Directions() []Direction {
+	return directions[:]
+}