Implements interface for changing the view distance.

Uses default view distance if player's view distance is not set

Throws an illegal argument exception if view distance is set too high
or too low.

Pushes notifications of server and world view distance changes to the player.
Move view distance functions from PlayerManger to WorldServer.
Set player minimum view distance to 1 for now.
Reset player's 'last known' position when recalculating visible chunks.

Use per-player view distance in chunk distance checks

src/main/java/net/minecraft/server/EntityPlayer.java

@@ -29,6 +29,16 @@ public class EntityPlayer extends EntityHuman implements ICrafting {
     private int bO = 0;
     public boolean h;
 
+    // CraftBukkit start - extra variables
+    private boolean viewDistanceSet;
+    private int viewDistance; // set view distance on a per player basis
+    private int actualViewDistance; // when view distance in the world changes, need to know how far I could previously see
+    public String displayName;
+    public org.bukkit.Location compassTarget;
+    public long timeOffset = 0;
+    public boolean relativeTime = true;
+    // CraftBukkit end
+
     public EntityPlayer(MinecraftServer minecraftserver, World world, String s, ItemInWorldManager iteminworldmanager) {
         super(world);
         iteminworldmanager.player = this;
@@ -51,13 +61,12 @@ public class EntityPlayer extends EntityHuman implements ICrafting {
         this.height = 0.0F;
 
         // CraftBukkit start
+        this.viewDistanceSet = false;
+        this.actualViewDistance = getViewDistance(); // set the 'current' view distance. This value will be updated any time the actual view distance changes
         this.displayName = this.name;
+        // CraftBukkit end
     }
 
-    public String displayName;
-    public org.bukkit.Location compassTarget;
-    // CraftBukkit end
-
     public void spawnIn(World world) {
         super.spawnIn(world);
         // CraftBukkit - world fallback code, either respawn location or global spawn
@@ -483,8 +492,6 @@ public class EntityPlayer extends EntityHuman implements ICrafting {
     }
 
     // CraftBukkit start
-    public long timeOffset = 0;
-    public boolean relativeTime = true;
 
     public long getPlayerTime() {
         if (this.relativeTime) {
@@ -500,5 +507,55 @@ public class EntityPlayer extends EntityHuman implements ICrafting {
     public String toString() {
         return super.toString() + "(" + this.name + " at " + this.locX + "," + this.locY + "," + this.locZ + ")";
     }
+
+    public void setViewDistance(int viewDistance) {
+        if (viewDistance < 1) { // for now must set view distance to 1 or higher. 0 might be possible, but it breaks the game at the moment
+            viewDistance = 1;
+        }
+        this.viewDistance = viewDistance;
+        this.viewDistanceSet = true;
+        updateViewDistance();
+    }
+
+    public int getViewDistance() {
+        if (viewDistanceSet) {
+            return viewDistance;
+        } else {
+            return defaultViewDistance();
+        }
+    }
+
+    private int defaultViewDistance() {
+        org.bukkit.World world = getBukkitEntity().getWorld();
+        if (world != null) {
+            return world.getViewDistance();
+        } else {
+            return getBukkitEntity().getServer().getViewDistance();
+        }
+    }
+
+    public void resetViewDistance() {
+        this.viewDistanceSet = false;
+        updateViewDistance();
+    }
+
+    public boolean isViewDistanceSet() {
+        return viewDistanceSet;
+    }
+
+    /**
+     * Should be called every time the view distance might have changed.
+     * Ensures we are always aware of the current and previous view distances.
+     *
+     * synchronized so that we are always sure that we have accurately tracked the view distance changes
+     */
+    public synchronized void updateViewDistance() {
+        if (actualViewDistance == getViewDistance()) {
+            return;
+        }
+        // notify the player manager that our view distance may have changed
+        ((CraftWorld) getBukkitEntity().getWorld()).getHandle().manager.updatePlayerViewDistance(this, actualViewDistance, getViewDistance());
+        actualViewDistance = getViewDistance();
+    }
     // CraftBukkit end
 }