Adds some helper functions to make getting direction-related values easier

Adds a function for getting the yaw given two locations
Adds a function for getting a block face given a yaw

src/main/java/net/knarcraft/stargate/utility/DirectionHelper.java

@@ -3,6 +3,8 @@ package net.knarcraft.stargate.utility;
 import net.knarcraft.stargate.BlockLocation;
 import net.knarcraft.stargate.RelativeBlockVector;
 import org.bukkit.Location;
+import org.bukkit.block.BlockFace;
+import org.bukkit.util.Vector;
 
 /**
  * This class helps with direction-dependent (modX, modZ) calculations
@@ -13,6 +15,74 @@ public final class DirectionHelper {
 
     }
 
+    /**
+     * Gets a yaw by comparing two locations
+     *
+     * <p>The yaw here is the direction an observer a the first location has to look to face the second location.
+     * The yaw is only meant to be calculated for locations with equal x or equal z.</p>
+     *
+     * @param location1 <p>The first location, which works as the origin</p>
+     * @param location2 <p>The second location, which the yaw will point at</p>
+     * @return <p>The yaw</p>
+     */
+    public static float getYawFromLocationDifference(Location location1, Location location2) {
+        Location difference = location1.clone().subtract(location2.clone());
+        if (difference.getX() > 0) {
+            return 90;
+        } else if (difference.getX() < 0) {
+            return 270;
+        } else if (difference.getZ() > 0) {
+            return 180;
+        } else if (difference.getZ() < 0) {
+            return 0;
+        }
+        throw new IllegalArgumentException("Locations given are equal or at the same x and y axis");
+    }
+
+    /**
+     * Gets a block face given a yaw
+     * @param yaw <p>The yaw to use</p>
+     * @return <p>The block face the yaw corresponds to</p>
+     */
+    public static BlockFace getBlockFaceFromYaw(double yaw) {
+        //Make sure the yaw is between 0 and 360
+        yaw = normalizeYaw(yaw);
+
+        if (yaw == 0) {
+            return BlockFace.SOUTH;
+        } else if (yaw == 90) {
+            return BlockFace.WEST;
+        } else if (yaw == 180) {
+            return BlockFace.NORTH;
+        } else if (yaw == 270) {
+            return BlockFace.EAST;
+        } else {
+            throw new IllegalArgumentException("Invalid yaw given");
+        }
+    }
+
+    /**
+     * Gets a direction vector given a yaw
+     * @param yaw <p>The yaw to use</p>
+     * @return <p>The direction vector of the yaw</p>
+     */
+    public static Vector getDirectionVectorFromYaw(double yaw) {
+        //Make sure the yaw is between 0 and 360
+        yaw = normalizeYaw(yaw);
+
+        if (yaw == 0) {
+            return new Vector(0, 0, 1);
+        } else if (yaw == 90) {
+            return new Vector(-1, 0, 0);
+        } else if (yaw == 180) {
+            return new Vector(0, 0, -1);
+        } else if (yaw == 270) {
+            return new Vector(1, 0, 0);
+        } else {
+            throw new IllegalArgumentException("Invalid yaw given");
+        }
+    }
+
     /**
      * Gets the block at a relative block vector location
      *
@@ -38,4 +108,17 @@ public final class DirectionHelper {
         return location.add(-right * modX + distance * modZ, depth, -right * modZ + -distance * modX);
     }
 
+    /**
+     * Normalizes a yaw to make it positive and no larger than 360 degrees
+     * @param yaw <p>The yaw to normalize</p>
+     * @return <p>The normalized yaw</p>
+     */
+    private static double normalizeYaw(double yaw) {
+        while (yaw < 0) {
+            yaw += 360;
+        }
+        yaw = yaw % 360;
+        return yaw;
+    }
+
 }