Add more maths functions for the Vectors

pkg/game/geom.go

@@ -1,5 +1,7 @@
 package game
 
+import "math"
+
 // Vector desribes a 3D vector
 type Vector struct {
 	X float64 `json:"x"`
@@ -11,3 +13,25 @@ func (v *Vector) Add(v2 Vector) {
 	v.X += v2.X
 	v.Y += v2.Y
 }
+
+// Added calculates a new vector
+func (v Vector) Added(v2 Vector) Vector {
+	v.Add(v2)
+	return v
+}
+
+// Negated returns a negated vector
+func (v Vector) Negated() Vector {
+	return Vector{-v.X, -v.Y}
+}
+
+// Length returns the length of the vector
+func (v Vector) Length() float64 {
+	return math.Sqrt(v.X*v.X + v.Y*v.Y)
+}
+
+// Distance returns the distance between two vectors
+func (v Vector) Distance(v2 Vector) float64 {
+	// Negate the two vectors and calciate the length
+	return v.Added(v2.Negated()).Length()
+}