1 files changed, 38 insertions, 0 deletions
diff --git a/src/main/scala/sims/collision/Projection.scala b/src/main/scala/sims/collision/Projection.scala
new file mode 100644
index 0000000..7617263
--- /dev/null
+++ b/src/main/scala/sims/collision/Projection.scala
@@ -0,0 +1,38 @@
+/*    _____ _ __  ________    ___                                      *\
+**   / ___/(_)  |/  / ___/   |__ \  Simple Mechanics Simulator 2       **
+**   \__ \/ / /|_/ /\__ \    __/ /  copyright (c) 2011 Jakob Odersky   **
+**  ___/ / / /  / /___/ /   / __/                                      **
+** /____/_/_/  /_//____/   /____/                                      **
+\*                                                                     */
+
+package sims.collision
+
+import sims.math._
+
+/**Projection on an axis.
+ * <p>
+ * Projections are commonly used in SiMS for collision detection.
+ * @param axis directional vector of the axis of the projection
+ * @param lower lower value of the projection
+ * @param upper upper value of the projection*/
+case class Projection(axis: Vector2D,
+                      lower: Double,
+                      upper: Double) {
+  require(axis != Vector2D.Null, "A projection's axis cannot be given by a null vector!")
+  require(lower <= upper, "Invalid bounds. Lower must be less than or equal to upper.")
+  
+  /**Checks this projection for overlap with another projection.
+   * @throws IllegalArgumentExcepion if both projections have different axes*/
+  def overlaps(other: Projection): Boolean = {
+    require(axis == other.axis, "Cannot compare two projections on different axes!")
+      !((other.lower - this.upper) > 0 || (this.lower - other.upper) > 0)
+  }
+  
+  /**Returns the overlap between this projection and another projection.
+  * @throws IllegalArgumentExcepion if both projections have different axes*/
+  def overlap(other: Projection): Double = {
+    require(axis == other.axis, "Cannot compare two projections on different axes!")
+         math.min(upper, other.upper) - math.max(lower, other.lower)
+        
+  }
+}