Added Atan2, Len, Norm for PointF{,32}.

Added Dot for Point{,F,F32}

point.go

@@ -64,6 +64,11 @@ func (p Point) DistInt(q Point) int {
 	return ints.SubAbs(p.X, q.X) + ints.SubAbs(p.Y, q.Y)
 }
 
+// Dot returns the dot product of p and q.
+func (p Point) Dot(q Point) int {
+	return p.X*p.X + p.Y*p.Y
+}
+
 // In tests if the point p is inside the rectangle r.
 func (p Point) In(r Rectangle) bool {
 	if p.X < r.Min.X || p.X >= r.Max.X || p.Y < r.Min.Y || p.Y >= r.Max.Y {

pointf.go

@@ -39,9 +39,14 @@ func (p PointF) AngleTo(q PointF) float64 {
 	return a
 }
 
+// Atan2 returns the arc tangent of y/x.
+func (p PointF) Atan2() float64 {
+	return Atan2(p.Y, p.X)
+}
+
 // Distance calculates the distance between points p and q.
 func (p PointF) Distance(q PointF) float64 {
-	return math.Sqrt(p.Distance2(q))
+	return Sqrt(p.Distance2(q))
 }
 
 // Distance2 calculates the squared distance between points p and q.
@@ -101,6 +106,11 @@ func (p PointF) Div(t float64) PointF {
 	return PtF(p.X/t, p.Y/t)
 }
 
+// Dot returns the dot product of p and q.
+func (p PointF) Dot(q PointF) float64 {
+	return p.X*q.X + p.Y*q.Y
+}
+
 // In tests if the point p is inside the rectangle r.
 func (p PointF) In(r RectangleF) bool {
 	if p.X < r.Min.X || p.X >= r.Max.X || p.Y < r.Min.Y || p.Y >= r.Max.Y {
@@ -132,6 +142,11 @@ func (p PointF) Invert() PointF {
 	return PointF{-p.X, -p.Y}
 }
 
+// Len returns the length of the vector.
+func (p PointF) Len() float64 {
+	return Sqrt(p.X*p.X + p.Y*p.Y)
+}
+
 // Mul multiplies the X and Y values of point p with t and returns the result.
 func (p PointF) Mul(t float64) PointF {
 	return PtF(p.X*t, p.Y*t)
@@ -142,6 +157,11 @@ func (p PointF) Mul2D(x, y float64) PointF {
 	return PtF(p.X*x, p.Y*y)
 }
 
+// Norm returns the normalized vector of x and y.
+func (p PointF) Norm() PointF {
+	return p.Mul(1 / p.Len())
+}
+
 // Rect returns a rectangle starting from point p to given point q
 func (p PointF) Rect(q PointF) RectangleF {
 	return RectangleF{Min: p, Max: q}

pointf32.go

@@ -39,9 +39,14 @@ func (p PointF32) AngleTo(q PointF32) float32 {
 	return a
 }
 
+// Atan2 returns the arc tangent of y/x.
+func (p PointF32) Atan2() float32 {
+	return Atan232(p.Y, p.X)
+}
+
 // Distance calculates the distance between points p and q.
 func (p PointF32) Distance(q PointF32) float32 {
-	return float32(math.Sqrt(float64(p.Distance2(q))))
+	return Sqrt32(p.Distance2(q))
 }
 
 // Distance2 calculates the squared distance between points p and q.
@@ -101,6 +106,11 @@ func (p PointF32) Div(t float32) PointF32 {
 	return PtF32(p.X/t, p.Y/t)
 }
 
+// Dot returns the dot product of p and q.
+func (p PointF32) Dot(q PointF32) float32 {
+	return p.X*q.X + p.Y*q.Y
+}
+
 // In tests if the point p is inside the rectangle r.
 func (p PointF32) In(r RectangleF32) bool {
 	if p.X < r.Min.X || p.X >= r.Max.X || p.Y < r.Min.Y || p.Y >= r.Max.Y {
@@ -132,6 +142,11 @@ func (p PointF32) Invert() PointF32 {
 	return PointF32{-p.X, -p.Y}
 }
 
+// Len returns the length of the vector.
+func (p PointF32) Len() float32 {
+	return Sqrt32(p.X*p.X + p.Y*p.Y)
+}
+
 // Mul multiplies the X and Y values of point p with t and returns the result.
 func (p PointF32) Mul(t float32) PointF32 {
 	return PtF32(p.X*t, p.Y*t)
@@ -142,6 +157,11 @@ func (p PointF32) Mul2D(x, y float32) PointF32 {
 	return PtF32(p.X*x, p.Y*y)
 }
 
+// Norm returns the normalized vector of x and y.
+func (p PointF32) Norm() PointF32 {
+	return p.Mul(1 / p.Len())
+}
+
 // Rect returns a rectangle starting from point p to given point q
 func (p PointF32) Rect(q PointF32) RectangleF32 {
 	return RectangleF32{Min: p, Max: q}