Fix error when adding BO2s to a BO3 structure

Fixes #419.

The dangerous method CustomObjectCoordinate.getStructuredObject() has
been removed.

Author: rutgerkok

common/src/main/java/com/khorn/terraincontrol/customobjects/CustomObjectCoordinate.java

@@ -8,7 +8,7 @@
 import java.util.Random;
 
 /**
- * Holds a custom object along with the absolute spawn coordinates.
+ * Represents an object along with its location in the world.
  */
 public class CustomObjectCoordinate
 {
@@ -53,24 +53,12 @@ public CustomObject getObject()
         return object;
     }
 
-    /**
-     * Returns the object of this coordinate, casted to a
-     * StructuredCustomObject. Will throw a ClassCastExcpetion
-     * if the object isn't a StructuredCustomObject
-     *
-     * @return The casted object.
-     */
-    public StructuredCustomObject getStructuredObject()
-    {
-        return (StructuredCustomObject) object;
-    }
-
     public Rotation getRotation()
     {
         return rotation;
     }
 
-    public boolean spawnWithChecks(LocalWorld world, StructurePartSpawnHeight height, Random random)
+    boolean spawnWithChecks(LocalWorld world, StructurePartSpawnHeight height, Random random)
     {
         int y = height.getCorrectY(world, x, this.y, z);
         if (!object.canSpawnAt(world, rotation, x, y, z))
@@ -125,7 +113,7 @@ public int hashCode()
      * Gets the chunk that should populate for this object.
      * @return The chunk.
      */
-    public ChunkCoordinate getPopulatingChunk()
+    ChunkCoordinate getPopulatingChunk()
     {
         // In the past we simply returned the chunk populating for the origin
         // of the object. However, the origin is not guaranteed to be at the

common/src/main/java/com/khorn/terraincontrol/customobjects/CustomObjectStructure.java

@@ -2,15 +2,16 @@
 
 import com.khorn.terraincontrol.LocalWorld;
 import com.khorn.terraincontrol.util.ChunkCoordinate;
+import com.khorn.terraincontrol.util.Rotation;
 import com.khorn.terraincontrol.util.helpers.RandomHelper;
 
 import java.util.*;
 
 /**
- * This class creates the branch structure based on one parent object, and spawns all
- * objects that should spawn in a chunk.
- * 
- * Although it shouldn't be too slow to recalculate, a structure cache should be kept.
+ * Represents a collection of all {@link CustomObject}s in a structure. It is
+ * calculated by finding the branches of one object, then finding the branches
+ * of those branches, etc., until
+ * {@link StructuredCustomObject#getMaxBranchDepth()} is reached.
  *
  */
 public class CustomObjectStructure
@@ -19,20 +20,21 @@ public class CustomObjectStructure
     protected LocalWorld world;
     protected CustomObjectCoordinate start;
     protected StructurePartSpawnHeight height;
-    protected Map<ChunkCoordinate, Set<CustomObjectCoordinate>> objectsToSpawn;
-    protected int maxBranchDepth;
+    private Map<ChunkCoordinate, Set<CustomObjectCoordinate>> objectsToSpawn;
+    private int maxBranchDepth;
 
-    public CustomObjectStructure(LocalWorld world, CustomObjectCoordinate start)
+    CustomObjectStructure(LocalWorld world, CustomObjectCoordinate start)
     {
         if (!(start.getObject() instanceof StructuredCustomObject))
         {
             throw new IllegalArgumentException("Start object has to be a structure!");
         }
+        StructuredCustomObject object = (StructuredCustomObject) start.getObject();
 
         this.world = world;
         this.start = start;
-        this.height = start.getStructuredObject().getStructurePartSpawnHeight();
-        this.maxBranchDepth = start.getStructuredObject().getMaxBranchDepth();
+        this.height = object.getStructurePartSpawnHeight();
+        this.maxBranchDepth = object.getMaxBranchDepth();
         random = RandomHelper.getRandomForCoords(start.getX(), start.getY(), start.getZ(), world.getSeed());
 
         // Calculate all branches and add them to a list
@@ -43,7 +45,7 @@ public CustomObjectStructure(LocalWorld world, CustomObjectCoordinate start)
 
     private void addBranches(CustomObjectCoordinate coordObject, int depth)
     {
-        for (Branch branch : coordObject.getStructuredObject().getBranches(coordObject.getRotation()))
+        for (Branch branch : getBranches(coordObject.getObject(), coordObject.getRotation()))
         {
             CustomObjectCoordinate childCoordObject = branch.toCustomObjectCoordinate(world, random, coordObject.getX(),
                     coordObject.getY(), coordObject.getZ());
@@ -65,12 +67,21 @@ private void addBranches(CustomObjectCoordinate coordObject, int depth)
         }
     }
 
+    private Branch[] getBranches(CustomObject customObject, Rotation rotation)
+    {
+        if (customObject instanceof StructuredCustomObject)
+        {
+            return ((StructuredCustomObject) customObject).getBranches(rotation);
+        }
+        return new Branch[0];
+    }
+
     /**
      * Adds the object to the spawn list of each chunk that the object
      * touches.
      * @param coordObject The object.
      */
-    void addToSpawnList(CustomObjectCoordinate coordObject)
+    private void addToSpawnList(CustomObjectCoordinate coordObject)
     {
         ChunkCoordinate chunkCoordinate = coordObject.getPopulatingChunk();
 
@@ -83,6 +94,10 @@ void addToSpawnList(CustomObjectCoordinate coordObject)
         objectsInChunk.add(coordObject);
     }
 
+    /**
+     * Spawns all the objects that should be spawned in that chunk.
+     * @param chunkCoordinate The chunk to spawn in.
+     */
     public void spawnForChunk(ChunkCoordinate chunkCoordinate)
     {
         Set<CustomObjectCoordinate> objectsInChunk = objectsToSpawn.get(chunkCoordinate);