Fixed Polars.calculateVMG function - it was using non-existent keys in some circumstances.

#story[873] #pair[fjc40,jam339]

mock/src/main/java/seng302/Model/Polars.java

@@ -35,7 +35,6 @@ public class Polars {
         polarValues.put(newKey, boatSpeed);
     }
 
-    //TODO calculate VMG from (windAngle, destAngle, windSpeed).
 
     /**
      * Calculates the VMG for a given wind angle, wind speed, and angle to destination.
@@ -65,15 +64,22 @@ public class Polars {
         ArrayList<Double> windAngles = new ArrayList<>();
         for (Pair<Double, Double> key : this.polarValues.keySet()) {
 
-            windAngles.add(key.getValue());
+            //Don't add angles multiple times.
+            double angle = key.getValue();
+            if (!windAngles.contains(angle)) {
+                windAngles.add(angle);
+            }
         }
 
         //Find the angle with the best VMG.
+        //TODO need to differentiate between windward and leeward.
         double bestVMGAngle = 0;
         double bestVMGVelocity = 0;
         for (double tackAngle : windAngles) {
+            Pair<Double,Double> key = new Pair<Double,Double>(polarWindSpeed, tackAngle);
+            if (this.polarValues.containsKey(key)) {
                 //This is the velocity from the polar table at this wind speed/angle.
-            double estVelocity = this.polarValues.get(new Pair<Double,Double>(polarWindSpeed, tackAngle));
+                double estVelocity = this.polarValues.get(key);
                 double angleBetweenDestAndTack = tackAngle - destinationAngle;
                 //This is the estimated velocity towards the target (e.g., angling away from the target reduces velocity).
                 double vmgTemp = Math.cos(angleBetweenDestAndTack) * estVelocity;
@@ -86,6 +92,9 @@ public class Polars {
 
             }
 
+        }
+
+        System.out.println("VMG speed = " + bestVMGVelocity + " , VMG angle = " + bestVMGAngle);//TEMP DEBUG REMOVE
 
         //Create the VMG object and return it.
         return new VMG(bestVMGVelocity, bestVMGAngle);