* Blocks can now be Spawned and Removed. Used when it's placed/destro…

…yed by the server, not by the player.

* Added basic block physics features - falling sand and gravel. See #52, #94

Chraft/Chraft.csproj

@@ -256,6 +256,9 @@
     <Compile Include="World\Blocks\BlockPistonHead.cs" />
     <Compile Include="World\Blocks\BlockSponge.cs" />
     <Compile Include="World\Blocks\BlockStickyPiston.cs" />
+    <Compile Include="World\Blocks\Physics\BlockBasePhysics.cs" />
+    <Compile Include="World\Blocks\Physics\FallingSand.cs" />
+    <Compile Include="World\Blocks\Physics\FallingGravel.cs" />
     <Compile Include="World\ChunkLightUpdate.cs" />
     <Compile Include="World\Location.cs" />
     <Compile Include="Entity\Mob.cs" />

Chraft/World/Blocks/BlockBase.cs

@@ -157,6 +157,25 @@ public virtual void Destroy(EntityBase entity, StructBlock block)
             NotifyNearbyBlocks(entity, block);
         }
 
+        /// <summary>
+        /// Removes the block from the world. Don't drop anything.
+        /// </summary>
+        /// <param name="block">block that is being removed</param>
+        public virtual void Remove(StructBlock block)
+        {
+            UpdateOnDestroy(block);
+            NotifyNearbyBlocks(null, block);
+        }
+
+        /// <summary>
+        /// Spawns the block in the world (not placed by the player)
+        /// </summary>
+        /// <param name="block">block that is being spawned</param>
+        public virtual void Spawn(StructBlock block)
+        {
+            UpdateOnPlace(block);
+        }
+
         /// <summary>
         /// Notifies the nearby block that the current block has been destroyed
         /// May be used by recipient block to start the physic simulation etc

Chraft/World/Blocks/BlockGravel.cs

@@ -5,6 +5,7 @@
 using Chraft.Entity;
 using Chraft.Interfaces;
 using Chraft.Plugins.Events.Args;
+using Chraft.World.Blocks.Physics;
 
 namespace Chraft.World.Blocks
 {
@@ -39,5 +40,41 @@ protected override void DropItems(EntityBase entity, StructBlock block)
             }
             base.DropItems(entity, block);
         }
+
+        public override void NotifyDestroy(EntityBase entity, StructBlock sourceBlock, StructBlock targetBlock)
+        {
+            if ((targetBlock.Coords.WorldY - sourceBlock.Coords.WorldY) == 1 &&
+                    targetBlock.Coords.WorldX == sourceBlock.Coords.WorldX &&
+                    targetBlock.Coords.WorldZ == sourceBlock.Coords.WorldZ)
+            {
+                StartPhysics(targetBlock);
+            }
+            base.NotifyDestroy(entity, sourceBlock, targetBlock);
+        }
+
+        public override void Place(EntityBase entity, StructBlock block, StructBlock targetBlock, BlockFace face)
+        {
+            if (!CanBePlacedOn(entity, block, targetBlock, face))
+                return;
+
+            if (!RaisePlaceEvent(entity, block))
+                return;
+
+            UpdateOnPlace(block);
+
+            RemoveItem(entity);
+
+            if (block.Coords.WorldY > 1)
+                if (block.World.GetBlockId(block.Coords.WorldX, block.Coords.WorldY - 1, block.Coords.WorldZ) == (byte)BlockData.Blocks.Air)
+                    StartPhysics(block);
+        }
+
+        protected void StartPhysics(StructBlock block)
+        {
+            Remove(block);
+            FallingGravel fgBlock = new FallingGravel(block.World, new Location(block.Coords.WorldX + 0.5, block.Coords.WorldY + 0.5, block.Coords.WorldZ + 0.5));
+            fgBlock.Start();
+            block.World.PhysicsBlocks.TryAdd(fgBlock.EntityId, fgBlock);
+        }
     }
 }

Chraft/World/Blocks/BlockSand.cs

@@ -5,6 +5,7 @@
 using Chraft.Entity;
 using Chraft.Interfaces;
 using Chraft.Plugins.Events.Args;
+using Chraft.World.Blocks.Physics;
 
 namespace Chraft.World.Blocks
 {
@@ -17,5 +18,41 @@ public BlockSand()
             IsSolid = true;
             LootTable.Add(new ItemStack((short)Type, 1));
         }
+
+        public override void NotifyDestroy(EntityBase entity, StructBlock sourceBlock, StructBlock targetBlock)
+        {
+            if ((targetBlock.Coords.WorldY - sourceBlock.Coords.WorldY) == 1 &&
+                    targetBlock.Coords.WorldX == sourceBlock.Coords.WorldX &&
+                    targetBlock.Coords.WorldZ == sourceBlock.Coords.WorldZ)
+            {
+                StartPhysics(targetBlock);
+            }
+            base.NotifyDestroy(entity, sourceBlock, targetBlock);
+        }
+
+        public override void Place(EntityBase entity, StructBlock block, StructBlock targetBlock, BlockFace face)
+        {
+            if (!CanBePlacedOn(entity, block, targetBlock, face))
+                return;
+
+            if (!RaisePlaceEvent(entity, block))
+                return;
+
+            UpdateOnPlace(block);
+
+            RemoveItem(entity);
+
+            if (block.Coords.WorldY > 1)
+                if (block.World.GetBlockId(block.Coords.WorldX, block.Coords.WorldY - 1, block.Coords.WorldZ) == (byte)BlockData.Blocks.Air)
+                    StartPhysics(block);
+        }
+
+        protected void StartPhysics(StructBlock block)
+        {
+            Remove(block);
+            FallingSand fsBlock = new FallingSand(block.World, new Location(block.Coords.WorldX + 0.5, block.Coords.WorldY + 0.5, block.Coords.WorldZ + 0.5));
+            fsBlock.Start();
+            block.World.PhysicsBlocks.TryAdd(fsBlock.EntityId, fsBlock);
+        }
     }
 }

Chraft/World/Blocks/Physics/BlockBasePhysics.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using Chraft.Net.Packets;
+using Chraft.Utils;
+
+namespace Chraft.World.Blocks.Physics
+{
+    public abstract class BlockBasePhysics
+    {
+        public int EntityId { get; protected set; }
+        public WorldManager World { get; protected set; }
+        public Location Position { get; protected set; }
+        public bool IsPlaying { get; protected set; }
+        public Vector3 Velocity { get; protected set; }
+        public AddObjectVehiclePacket.ObjectType Type;
+
+        protected BlockBasePhysics(WorldManager world, Location pos)
+        {
+            World = world;
+            Position = pos;
+            EntityId = world.Server.AllocateEntity();
+
+            CreateEntityPacket entity = new CreateEntityPacket { EntityId = EntityId };
+            foreach (var nearbyPlayer in World.Server.GetNearbyPlayers(World, new AbsWorldCoords(Position.X, Position.Y, Position.Z)))
+            {
+                nearbyPlayer.SendPacket(entity);
+            }
+        }
+
+        public virtual void Start()
+        {
+            if (IsPlaying)
+                return;
+            AddObjectVehiclePacket obj = new AddObjectVehiclePacket
+                                             {
+                                                 EntityId = EntityId,
+                                                 Type = Type,
+                                                 UnknownFlag = 0,
+                                                 X = Position.X,
+                                                 Y = Position.Y,
+                                                 Z = Position.Z
+                                             };
+            foreach (var nearbyPlayer in World.Server.GetNearbyPlayers(World, new AbsWorldCoords(Position.X, Position.Y, Position.Z)))
+            {
+                nearbyPlayer.SendPacket(obj);
+            }
+            IsPlaying = true;
+        }
+
+        public virtual void Simulate()
+        {
+        }
+
+        public virtual void Stop()
+        {
+            IsPlaying = false;
+            BlockBasePhysics unused = null;
+            World.PhysicsBlocks.TryRemove(EntityId, out unused);
+            DestroyEntityPacket entity = new DestroyEntityPacket { EntityId = EntityId };
+            foreach (var nearbyPlayer in World.Server.GetNearbyPlayers(World, new AbsWorldCoords(Position.X, Position.Y, Position.Z)))
+            {
+                nearbyPlayer.SendPacket(entity);
+            }
+            OnStop();
+        }
+
+        protected virtual void OnStop()
+        {
+        }
+    }
+}

Chraft/World/Blocks/Physics/FallingGravel.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using Chraft.Utils;
+
+namespace Chraft.World.Blocks.Physics
+{
+    public class FallingGravel : FallingSand
+    {
+        public FallingGravel(WorldManager world, Location pos) : base(world, pos)
+        {
+            Type = Net.Packets.AddObjectVehiclePacket.ObjectType.FallingGravel;
+            BlockId = (byte) BlockData.Blocks.Gravel;
+        }
+    }
+}

Chraft/World/Blocks/Physics/FallingSand.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using Chraft.Utils;
+
+namespace Chraft.World.Blocks.Physics
+{
+    public class FallingSand : BlockBasePhysics
+    {
+        protected byte BlockId;
+
+        public FallingSand(WorldManager world, Location pos) : base(world, pos)
+        {
+            Type = Net.Packets.AddObjectVehiclePacket.ObjectType.FallingSand;
+            BlockId = (byte) BlockData.Blocks.Sand;
+            Velocity = new Vector3(0, -0.4D, 0);
+        }
+
+        public override void Simulate()
+        {
+            int x = MathHelper.floor_double(Position.X);
+            int y = MathHelper.floor_double(Position.Y);
+            int z = MathHelper.floor_double(Position.Z);
+            byte blockId = World.GetBlockId(x, y, z);
+            if (blockId != (byte)BlockData.Blocks.Air)
+            {
+                Stop();
+                return;
+            }
+
+            if (Position.Y <= 1)
+            {
+                Stop();
+                return;
+            }
+
+            Position.Vector += Velocity;
+        }
+
+        protected override void OnStop()
+        {
+            UniversalCoords uc = UniversalCoords.FromWorld(MathHelper.floor_double(Position.X), MathHelper.floor_double(Position.Y) + 1, MathHelper.floor_double(Position.Z));
+            StructBlock block = new StructBlock(uc, BlockId, 0, World);
+            BlockHelper.Instance(BlockId).Spawn(block);
+            base.OnStop();
+        }
+    }
+}

Chraft/World/WorldManager.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.Linq;
 using System.Threading;
 using Chraft.Net;
@@ -7,6 +8,7 @@
 using System.IO;
 using Chraft.Entity;
 using Chraft.World.Blocks;
+using Chraft.World.Blocks.Physics;
 using Chraft.World.Weather;
 using Chraft.Plugins.Events.Args;
 using System.Threading.Tasks;
@@ -40,6 +42,9 @@ public partial class WorldManager : IDisposable
 
         public ConcurrentQueue<ChunkLightUpdate> ChunksToRecalculate;
 
+        public ConcurrentDictionary<int, BlockBasePhysics> PhysicsBlocks;
+        private Task _PhysicsSimulationTask;
+
         private readonly object ChunkLightUpdateLock = new object();
         private Task _GrowStuffTask;
         private Task _CollectTask;
@@ -175,6 +180,7 @@ public bool Load()
             _ChunkProvider = new ChunkProvider(this);
             Generator = _ChunkProvider.GetNewGenerator(GeneratorType.Custom, GetSeed());
             ChunkManager = new WorldChunkManager(this);
+            PhysicsBlocks = new ConcurrentDictionary<int, BlockBasePhysics>();
 
             InitializeSpawn();
             InitializeThreads();
@@ -354,7 +360,12 @@ private void GlobalTickProc(object state)
                 }
             }
 
-
+            if (_PhysicsSimulationTask == null || _PhysicsSimulationTask.IsCompleted)
+            {
+                _PhysicsSimulationTask = new Task(PhysicsProc);
+                _PhysicsSimulationTask.Start();
+            }
+
         }
 
         public Chunk GetChunkFromPosition(int x, int z)
@@ -421,6 +432,14 @@ private void GrowProc()
             }
         }
 
+        private void PhysicsProc()
+        {
+            foreach (var physicsBlock in PhysicsBlocks)
+            {
+                physicsBlock.Value.Simulate();
+            }
+        }
+
         private void EntityMoverStart()
         {
             Thread thread = new Thread(MovementThread);
@@ -705,21 +724,6 @@ private void UpdatePhysics(UniversalCoords coords, bool updateClients = true)
         {
             BlockData.Blocks type = (BlockData.Blocks)GetBlockId(coords);
             UniversalCoords oneDown = UniversalCoords.FromWorld(coords.WorldX, coords.WorldY - 1, coords.WorldZ);
-            if (type == BlockData.Blocks.Sand && coords.WorldY > 0 && GetBlockId(oneDown) == 0)
-            {
-                SetBlockAndData(coords, 0, 0);
-                SetBlockAndData(oneDown, (byte)BlockData.Blocks.Sand, 0);
-                Update(oneDown, updateClients);
-                return;
-            }
-
-            if (type == BlockData.Blocks.Gravel && coords.WorldY > 0 && GetBlockId(UniversalCoords.FromWorld(coords.WorldX, coords.WorldY - 1, coords.WorldZ)) == 0)
-            {
-                SetBlockAndData(coords, 0, 0);
-                SetBlockAndData(oneDown, (byte)BlockData.Blocks.Gravel, 0);
-                Update(oneDown, updateClients);
-                return;
-            }
 
             if (type == BlockData.Blocks.Water)
             {