1 files changed, 83 insertions, 0 deletions
diff --git a/src/main/scala/sims/geometry/Vector2D.scala b/src/main/scala/sims/geometry/Vector2D.scala
new file mode 100644
index 0000000..8d5205f
--- /dev/null
+++ b/src/main/scala/sims/geometry/Vector2D.scala
@@ -0,0 +1,83 @@
+/*
+ * Simple Mechanics Simulator (SiMS)
+ * copyright (c) 2009 Jakob Odersky
+ * made available under the MIT License
+*/
+
+package sims.geometry
+
+import scala.math._
+
+/**A 2D vector.
+ * @param x 1st component
+ * @param y 2nd component*/
+case class Vector2D(x: Double, y: Double) {
+    
+  /**Vector addition.*/
+  def +(v: Vector2D): Vector2D = Vector2D(x + v.x, y + v.y)
+  
+  /**Vector substraction.*/
+  def -(v: Vector2D): Vector2D = this + (v * -1)
+  
+  /**Scalar multiplication.*/
+  def *(n: Double): Vector2D = Vector2D(x * n, y * n)
+  
+  /**Scalar division.*/
+  def /(n: Double): Vector2D = this * (1/n)
+  
+  /**Unary minus.*/
+  def unary_- : Vector2D = Vector2D(-x, -y)
+  
+  /**Dot product.*/
+  def dot(v: Vector2D): Double = x * v.x + y * v.y
+  
+  /**Cross product. Length only because in 2D. The direction would be given by the x3-axis.*/
+  def cross(v: Vector2D): Double = x * v.y - y * v.x
+  
+  /**Norm or length of this vector.*/
+  val length: Double = math.sqrt(x * x + y * y)
+  
+  /**Unit vector.*/
+  def unit: Vector2D = if (!(x == 0.0 && y == 0.0)) Vector2D(x / length, y / length) 
+    else throw new IllegalArgumentException("Null vector does not have a unit vector.")
+  
+  /**Returns the projection of this vector onto the vector <code>v</code>.*/
+  def project(v: Vector2D): Vector2D = {
+    if (v != Vector2D.Null)
+      v * ((this dot v) / (v dot v))
+    else
+      Vector2D.Null
+    }
+  
+  /**Returns a rotation of this vector by <code>angle</code> radian.*/
+  def rotate(angle: Double): Vector2D = {
+    Vector2D(cos(angle) * x - sin(angle) * y,
+             cos(angle) * y + sin(angle) * x)
+  }
+  
+  /**Left normal vector. (-y, x)*/
+  def leftNormal: Vector2D = Vector2D(-y, x)
+  
+  /**Right normal vector. (y, -x)*/
+  def rightNormal: Vector2D = Vector2D(y, -x)
+  
+  /**Checks if this vector is the null vector.*/
+  def isNull: Boolean = this == Vector2D.Null
+  
+  /**Returns a list of this vector's components.*/
+  def components = List(x, y)
+}
+
+/**Contains special vectors.*/
+object Vector2D {
+  
+  /**Null vector.*/
+  val Null = Vector2D(0,0)
+  
+  /**Horizontal unit vector. (1,0)*/
+  val i = Vector2D(1,0)
+  
+  /**Vertical unit vector. (0,1)*/
+  val j = Vector2D(0,1)
+}
+