From 721a10ef1027d1ad756552b14848d39dd3cc9cea Mon Sep 17 00:00:00 2001
From: faiface <faiface@ksp.sk>
Date: Sun, 15 Oct 2017 19:50:41 +0200
Subject: [PATCH] add Vec.Project

---
 geometry.go | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/geometry.go b/geometry.go
index 00419ad..0cb1436 100644
--- a/geometry.go
+++ b/geometry.go
@@ -144,6 +144,14 @@ func (u Vec) Cross(v Vec) float64 {
 	return u.X*v.Y - v.X*u.Y
 }
 
+// Project returns a projection (or component) of vector u in the direction of vector v.
+//
+// Behaviour is undefined if v is a zero vector.
+func (u Vec) Project(v Vec) Vec {
+	len := u.Dot(v) / v.Len()
+	return v.Unit().Scaled(len)
+}
+
 // Map applies the function f to both x and y components of the vector u and returns the modified
 // vector.
 //