better rotation mechanics

src/main/java/core/ExMath.java

@@ -0,0 +1,28 @@
+package core;
+
+/**
+ * Extended Math functions for the game engine
+ */
+public class ExMath {
+
+    private ExMath(){
+    }
+
+    /**
+     * Lerp an angle in radians
+     *
+     * @param from The start angle
+     * @param to The target angle
+     * @param t The value
+     * @return The new angle
+     *
+     * @see <a href="https://gist.github.com/shaunlebron/8832585"angleLerp</a>
+     */
+    public static double angleLerp(double from, double to, double t) {
+        double max = Math.PI * 2;
+        double da = (to - from) % max;
+        double shortAngleDist = 2 * da % max - da;
+
+        return from + shortAngleDist * t;
+    }
+}

src/main/java/core/Vector2D.java

@@ -133,6 +133,30 @@ public class Vector2D {
         return new Vector2D(rotatedX + center.x, rotatedY + center.y);
     }
 
+    /**
+     * Rotate a point around another point
+     *
+     * This method can now be trusted
+     *
+     * @param center The center of the rotation
+     * @param value The point to be rotated, absolut to the center
+     * @param rotation The rotation angle in radians
+     * @return The rotated point
+     */
+    public static Vector2D rotateAround(Vector2D center, Vector2D value, double rotation){
+        return rotateAround(center, value, rotation, COUNTERCLOCKWISE);
+    }
+
+
+    /**
+     * Get a unit vector with magnitude 1 and the direction
+     * @param direction The direction of the vector
+     * @return The unit vector
+     */
+    public static Vector2D getUnitVector(double direction){
+        return rotateAround(new Vector2D(), new Vector2D(0, 1), direction);
+    }
+
     /**
      * Copy this object
      * @return A copy of this object
@@ -165,4 +189,8 @@ public class Vector2D {
         if (Double.compare(vector2D.x, x) != 0) return false;
         return Double.compare(vector2D.y, y) == 0;
     }
+
+    public double getRotation() {
+        return Math.atan2(y, x);
+    }
 }