Added better client state information, more message reorganization.

client/src/main/java/nl/andrewl/aos2_client/Camera.java

@@ -1,6 +1,7 @@
 package nl.andrewl.aos2_client;
 
 import nl.andrewl.aos_core.MathUtils;
+import nl.andrewl.aos_core.model.Player;
 import org.joml.Matrix4f;
 import org.joml.Vector2f;
 import org.joml.Vector3f;
@@ -46,6 +47,11 @@ public class Camera {
 		this.viewTransform = new Matrix4f();
 	}
 
+	public void setToPlayer(Player p) {
+		position.set(p.getPosition());
+		velocity.set(p.getVelocity());
+	}
+
 	public Matrix4f getViewTransform() {
 		return viewTransform;
 	}

client/src/main/java/nl/andrewl/aos2_client/Client.java

@@ -5,12 +5,15 @@ import nl.andrewl.aos2_client.control.InputHandler;
 import nl.andrewl.aos2_client.control.PlayerInputKeyCallback;
 import nl.andrewl.aos2_client.control.PlayerInputMouseClickCallback;
 import nl.andrewl.aos2_client.control.PlayerViewCursorCallback;
+import nl.andrewl.aos2_client.model.ClientPlayer;
 import nl.andrewl.aos2_client.render.GameRenderer;
 import nl.andrewl.aos_core.config.Config;
 import nl.andrewl.aos_core.model.world.ColorPalette;
-import nl.andrewl.aos_core.net.*;
+import nl.andrewl.aos_core.net.client.*;
-import nl.andrewl.aos_core.net.udp.ChunkUpdateMessage;
+import nl.andrewl.aos_core.net.world.ChunkDataMessage;
-import nl.andrewl.aos_core.net.udp.PlayerUpdateMessage;
+import nl.andrewl.aos_core.net.world.ChunkHashMessage;
+import nl.andrewl.aos_core.net.world.ChunkUpdateMessage;
+import nl.andrewl.aos_core.net.world.WorldInfoMessage;
 import nl.andrewl.record_net.Message;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -28,13 +31,13 @@ public class Client implements Runnable {
 	private final InputHandler inputHandler;
 	private final GameRenderer gameRenderer;
 
-	private int clientId;
 	private final ClientWorld world;
+	private ClientPlayer player;
 
 	public Client(ClientConfig config) {
 		this.config = config;
 		this.communicationHandler = new CommunicationHandler(this);
-		this.inputHandler = new InputHandler(communicationHandler);
+		this.inputHandler = new InputHandler(this, communicationHandler);
 		this.world = new ClientWorld();
 		this.gameRenderer = new GameRenderer(config.display, world);
 	}
@@ -43,17 +46,30 @@ public class Client implements Runnable {
 		return config;
 	}
 
+	public ClientPlayer getPlayer() {
+		return player;
+	}
+
+	/**
+	 * Called by the {@link CommunicationHandler} when a connection is
+	 * established, and we need to begin tracking the player's state.
+	 * @param player The player.
+	 */
+	public void setPlayer(ClientPlayer player) {
+		this.player = player;
+	}
+
 	@Override
 	public void run() {
 		try {
-			this.clientId = communicationHandler.establishConnection();
+			communicationHandler.establishConnection();
 		} catch (IOException e) {
 			log.error("Couldn't connect to the server: {}", e.getMessage());
 			return;
 		}
 
 		gameRenderer.setupWindow(
-				new PlayerViewCursorCallback(config.input, gameRenderer.getCamera(), communicationHandler),
+				new PlayerViewCursorCallback(config.input, this, gameRenderer.getCamera(), communicationHandler),
 				new PlayerInputKeyCallback(inputHandler),
 				new PlayerInputMouseClickCallback(inputHandler)
 		);
@@ -75,30 +91,37 @@ public class Client implements Runnable {
 	public void onMessageReceived(Message msg) {
 		if (msg instanceof WorldInfoMessage worldInfo) {
 			world.setPalette(ColorPalette.fromArray(worldInfo.palette()));
-		}
+		} else if (msg instanceof ChunkDataMessage chunkDataMessage) {
-		if (msg instanceof ChunkDataMessage chunkDataMessage) {
 			world.addChunk(chunkDataMessage);
-		}
+		} else if (msg instanceof ChunkUpdateMessage u) {
-		if (msg instanceof ChunkUpdateMessage u) {
 			world.updateChunk(u);
 			// If we received an update for a chunk we don't have, request it!
 			if (world.getChunkAt(u.getChunkPos()) == null) {
 				communicationHandler.sendMessage(new ChunkHashMessage(u.cx(), u.cy(), u.cz(), -1));
 			}
-		}
+		} else if (msg instanceof PlayerUpdateMessage playerUpdate) {
-		if (msg instanceof PlayerUpdateMessage playerUpdate) {
+			if (playerUpdate.clientId() == player.getId()) {
-			if (playerUpdate.clientId() == clientId) {
+				player.getPosition().set(playerUpdate.px(), playerUpdate.py(), playerUpdate.pz());
+				player.getVelocity().set(playerUpdate.vx(), playerUpdate.vy(), playerUpdate.vz());
+				gameRenderer.getCamera().setToPlayer(player);
+				// TODO: Add getEyeHeight() and isCrouching() to main Player class.
 				float eyeHeight = playerUpdate.crouching() ? 1.3f : 1.7f;
-				gameRenderer.getCamera().setPosition(playerUpdate.px(), playerUpdate.py() + eyeHeight, playerUpdate.pz());
+				gameRenderer.getCamera().getPosition().y += eyeHeight;
-				gameRenderer.getCamera().setVelocity(playerUpdate.vx(), playerUpdate.vy(), playerUpdate.vz());
 			} else {
 				world.playerUpdated(playerUpdate);
 			}
-		}
+		} else if (msg instanceof ClientInventoryMessage inventoryMessage) {
-		if (msg instanceof PlayerJoinMessage joinMessage) {
+			player.setInventory(inventoryMessage.inv());
+			System.out.println("Got inventory!");
+		} else if (msg instanceof InventorySelectedStackMessage selectedStackMessage) {
+			player.getInventory().setSelectedIndex(selectedStackMessage.index());
+			System.out.println("Selected item stack: " + player.getInventory().getSelectedItemStack().getType().getName());
+		} else if (msg instanceof ItemStackMessage itemStackMessage) {
+			player.getInventory().getItemStacks().set(itemStackMessage.index(), itemStackMessage.stack());
+			System.out.println("Item stack updated: " + itemStackMessage.index());
+		} else if (msg instanceof PlayerJoinMessage joinMessage) {
 			world.playerJoined(joinMessage);
-		}
+		} else if (msg instanceof PlayerLeaveMessage leaveMessage) {
-		if (msg instanceof PlayerLeaveMessage leaveMessage) {
 			world.playerLeft(leaveMessage);
 		}
 	}

client/src/main/java/nl/andrewl/aos2_client/ClientWorld.java

@@ -5,11 +5,11 @@ import nl.andrewl.aos2_client.render.chunk.ChunkMeshGenerator;
 import nl.andrewl.aos_core.model.world.Chunk;
 import nl.andrewl.aos_core.model.Player;
 import nl.andrewl.aos_core.model.world.World;
-import nl.andrewl.aos_core.net.ChunkDataMessage;
+import nl.andrewl.aos_core.net.world.ChunkDataMessage;
-import nl.andrewl.aos_core.net.PlayerJoinMessage;
+import nl.andrewl.aos_core.net.client.PlayerJoinMessage;
-import nl.andrewl.aos_core.net.PlayerLeaveMessage;
+import nl.andrewl.aos_core.net.client.PlayerLeaveMessage;
-import nl.andrewl.aos_core.net.udp.ChunkUpdateMessage;
+import nl.andrewl.aos_core.net.world.ChunkUpdateMessage;
-import nl.andrewl.aos_core.net.udp.PlayerUpdateMessage;
+import nl.andrewl.aos_core.net.client.PlayerUpdateMessage;
 import org.joml.Vector3f;
 import org.joml.Vector3i;
 

client/src/main/java/nl/andrewl/aos2_client/CommunicationHandler.java

@@ -1,8 +1,12 @@
 package nl.andrewl.aos2_client;
 
+import nl.andrewl.aos2_client.model.ClientPlayer;
 import nl.andrewl.aos_core.Net;
 import nl.andrewl.aos_core.net.*;
-import nl.andrewl.aos_core.net.udp.DatagramInit;
+import nl.andrewl.aos_core.net.connect.ConnectAcceptMessage;
+import nl.andrewl.aos_core.net.connect.ConnectRejectMessage;
+import nl.andrewl.aos_core.net.connect.ConnectRequestMessage;
+import nl.andrewl.aos_core.net.connect.DatagramInit;
 import nl.andrewl.record_net.Message;
 import nl.andrewl.record_net.util.ExtendedDataInputStream;
 import nl.andrewl.record_net.util.ExtendedDataOutputStream;
@@ -33,7 +37,7 @@ public class CommunicationHandler {
 		this.client = client;
 	}
 	
-	public int establishConnection() throws IOException {
+	public void establishConnection() throws IOException {
 		if (socket != null && !socket.isClosed()) {
 			socket.close();
 		}
@@ -54,11 +58,11 @@ public class CommunicationHandler {
 		}
 		if (response instanceof ConnectAcceptMessage acceptMessage) {
 			this.clientId = acceptMessage.clientId();
+			client.setPlayer(new ClientPlayer(clientId, username));
 			establishDatagramConnection();
 			log.info("Connection to server established. My client id is {}.", clientId);
 			new Thread(new TcpReceiver(in, client::onMessageReceived)).start();
 			new Thread(new UdpReceiver(datagramSocket, (msg, packet) -> client.onMessageReceived(msg))).start();
-			return acceptMessage.clientId();
 		} else {
 			throw new IOException("Server returned an unexpected message: " + response);
 		}

client/src/main/java/nl/andrewl/aos2_client/config/ClientConfig.java

@@ -13,7 +13,7 @@ public class ClientConfig {
 
 	public static class DisplayConfig {
 		public boolean fullscreen = false;
-		public boolean captureCursor = true;
+		public boolean captureCursor = false;
 		public float fov = 70;
 	}
 }

client/src/main/java/nl/andrewl/aos2_client/control/InputHandler.java

@@ -1,7 +1,8 @@
 package nl.andrewl.aos2_client.control;
 
 import nl.andrewl.aos2_client.CommunicationHandler;
-import nl.andrewl.aos_core.net.udp.ClientInputState;
+import nl.andrewl.aos_core.net.client.ClientInputState;
+import nl.andrewl.aos2_client.Client;
 
 import static org.lwjgl.glfw.GLFW.*;
 
@@ -9,16 +10,24 @@ import static org.lwjgl.glfw.GLFW.*;
  * Class which manages the player's input, and sending it to the server.
  */
 public class InputHandler {
+	private final Client client;
 	private final CommunicationHandler comm;
 
 	private ClientInputState lastInputState = null;
 
-	public InputHandler(CommunicationHandler comm) {
+	public InputHandler(Client client, CommunicationHandler comm) {
+		this.client = client;
 		this.comm = comm;
 	}
 
 	public void updateInputState(long window) {
 		// TODO: Allow customized keybindings.
+		int selectedInventoryIndex;
+		selectedInventoryIndex = client.getPlayer().getInventory().getSelectedIndex();
+		if (glfwGetKey(window, GLFW_KEY_1) == GLFW_PRESS) selectedInventoryIndex = 0;
+		if (glfwGetKey(window, GLFW_KEY_2) == GLFW_PRESS) selectedInventoryIndex = 1;
+		if (glfwGetKey(window, GLFW_KEY_3) == GLFW_PRESS) selectedInventoryIndex = 2;
+
 		ClientInputState currentInputState = new ClientInputState(
 				comm.getClientId(),
 				glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS,
@@ -29,7 +38,8 @@ public class InputHandler {
 				glfwGetKey(window, GLFW_KEY_LEFT_CONTROL) == GLFW_PRESS,
 				glfwGetKey(window, GLFW_KEY_LEFT_SHIFT) == GLFW_PRESS,
 				glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_1) == GLFW_PRESS,
-				glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_2) == GLFW_PRESS
+				glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_2) == GLFW_PRESS,
+				selectedInventoryIndex
 		);
 		if (!currentInputState.equals(lastInputState)) {
 			comm.sendDatagramPacket(currentInputState);

client/src/main/java/nl/andrewl/aos2_client/control/PlayerViewCursorCallback.java

@@ -1,9 +1,10 @@
 package nl.andrewl.aos2_client.control;
 
 import nl.andrewl.aos2_client.Camera;
+import nl.andrewl.aos2_client.Client;
 import nl.andrewl.aos2_client.CommunicationHandler;
 import nl.andrewl.aos2_client.config.ClientConfig;
-import nl.andrewl.aos_core.net.udp.ClientOrientationState;
+import nl.andrewl.aos_core.net.client.ClientOrientationState;
 import org.lwjgl.glfw.GLFWCursorPosCallbackI;
 
 import java.util.concurrent.ForkJoinPool;
@@ -22,15 +23,17 @@ public class PlayerViewCursorCallback implements GLFWCursorPosCallbackI {
 	private static final int ORIENTATION_UPDATE_LIMIT = 20;
 
 	private final ClientConfig.InputConfig config;
+	private final Client client;
 	private final Camera camera;
 	private final CommunicationHandler comm;
 	private float lastMouseCursorX;
 	private float lastMouseCursorY;
 	private long lastOrientationUpdateSentAt = 0L;
 
-	public PlayerViewCursorCallback(ClientConfig.InputConfig config, Camera camera, CommunicationHandler comm) {
+	public PlayerViewCursorCallback(ClientConfig.InputConfig config, Client client, Camera cam, CommunicationHandler comm) {
 		this.config = config;
-		this.camera = camera;
+		this.client = client;
+		this.camera = cam;
 		this.comm = comm;
 	}
 
@@ -45,13 +48,18 @@ public class PlayerViewCursorCallback implements GLFWCursorPosCallbackI {
 		float dy = y - lastMouseCursorY;
 		lastMouseCursorX = x;
 		lastMouseCursorY = y;
-		camera.setOrientation(
+		client.getPlayer().setOrientation(
-				camera.getOrientation().x - dx * config.mouseSensitivity,
+				client.getPlayer().getOrientation().x - dx * config.mouseSensitivity,
-				camera.getOrientation().y - dy * config.mouseSensitivity
+				client.getPlayer().getOrientation().y - dy * config.mouseSensitivity
 		);
+		camera.setOrientation(client.getPlayer().getOrientation().x, client.getPlayer().getOrientation().y);
 		long now = System.currentTimeMillis();
 		if (lastOrientationUpdateSentAt + ORIENTATION_UPDATE_LIMIT < now) {
-			ForkJoinPool.commonPool().submit(() -> comm.sendDatagramPacket(new ClientOrientationState(comm.getClientId(), camera.getOrientation().x, camera.getOrientation().y)));
+			ForkJoinPool.commonPool().submit(() -> comm.sendDatagramPacket(new ClientOrientationState(
+					client.getPlayer().getId(),
+					client.getPlayer().getOrientation().x,
+					client.getPlayer().getOrientation().y
+			)));
 			lastOrientationUpdateSentAt = now;
 		}
 	}

client/src/main/java/nl/andrewl/aos2_client/model/ClientPlayer.java

@@ -0,0 +1,25 @@
+package nl.andrewl.aos2_client.model;
+
+import nl.andrewl.aos_core.model.Player;
+import nl.andrewl.aos_core.model.item.Inventory;
+
+import java.util.ArrayList;
+
+public class ClientPlayer extends Player {
+	private final Inventory inventory;
+
+	public ClientPlayer(int id, String username) {
+		super(id, username);
+		this.inventory = new Inventory(new ArrayList<>(), 0);
+	}
+
+	public Inventory getInventory() {
+		return inventory;
+	}
+
+	public void setInventory(Inventory inv) {
+		this.inventory.getItemStacks().clear();
+		this.inventory.getItemStacks().addAll(inv.getItemStacks());
+		this.inventory.setSelectedIndex(inv.getSelectedIndex());
+	}
+}

core/src/main/java/nl/andrewl/aos_core/Net.java

@@ -1,7 +1,14 @@
 package nl.andrewl.aos_core;
 
-import nl.andrewl.aos_core.net.*;
+import nl.andrewl.aos_core.net.client.*;
-import nl.andrewl.aos_core.net.udp.*;
+import nl.andrewl.aos_core.net.connect.ConnectAcceptMessage;
+import nl.andrewl.aos_core.net.connect.ConnectRejectMessage;
+import nl.andrewl.aos_core.net.connect.ConnectRequestMessage;
+import nl.andrewl.aos_core.net.connect.DatagramInit;
+import nl.andrewl.aos_core.net.world.ChunkDataMessage;
+import nl.andrewl.aos_core.net.world.ChunkHashMessage;
+import nl.andrewl.aos_core.net.world.ChunkUpdateMessage;
+import nl.andrewl.aos_core.net.world.WorldInfoMessage;
 import nl.andrewl.record_net.Message;
 import nl.andrewl.record_net.Serializer;
 import nl.andrewl.record_net.util.ExtendedDataInputStream;
@@ -33,6 +40,10 @@ public final class Net {
 		serializer.registerType(11, PlayerJoinMessage.class);
 		serializer.registerType(12, PlayerLeaveMessage.class);
 		serializer.registerType(13, WorldInfoMessage.class);
+		// Separate serializers for client inventory messages.
+		serializer.registerTypeSerializer(14, new InventorySerializer());
+		serializer.registerTypeSerializer(15, new ItemStackSerializer());
+		serializer.registerType(16, InventorySelectedStackMessage.class);
 	}
 
 	public static ExtendedDataInputStream getInputStream(InputStream in) {

core/src/main/java/nl/andrewl/aos_core/model/item/BlockItemStack.java

@@ -1,13 +1,23 @@
 package nl.andrewl.aos_core.model.item;
 
 public class BlockItemStack extends ItemStack {
-	private int selectedValue = 1;
+	private byte selectedValue = 1;
 
-	public BlockItemStack(BlockItem item, int amount) {
+	public BlockItemStack(BlockItem item, int amount, byte selectedValue) {
 		super(item, amount);
+		this.selectedValue = selectedValue;
 	}
 
-	public int getSelectedValue() {
+	public BlockItemStack(BlockItem item) {
+		this(item, 50, (byte) 1);
+	}
+
+	public byte getSelectedValue() {
 		return selectedValue;
 	}
+
+	public void setSelectedValue(byte selectedValue) {
+		if (selectedValue < 1) return;
+		this.selectedValue = selectedValue;
+	}
 }

core/src/main/java/nl/andrewl/aos_core/model/item/GunItemStack.java

@@ -4,9 +4,29 @@ public class GunItemStack extends ItemStack {
 	private int bulletCount;
 	private int clipCount;
 
-	public GunItemStack(Gun gun) {
+	public GunItemStack(Gun gun, int bulletCount, int clipCount) {
 		super(gun, 1);
-		bulletCount = gun.getMaxBulletCount();
+		this.bulletCount = bulletCount;
-		clipCount = gun.getMaxClipCount();
+		this.clipCount = clipCount;
+	}
+
+	public GunItemStack(Gun gun) {
+		this(gun, gun.getMaxBulletCount(), gun.getMaxClipCount());
+	}
+
+	public int getBulletCount() {
+		return bulletCount;
+	}
+
+	public void setBulletCount(int bulletCount) {
+		this.bulletCount = bulletCount;
+	}
+
+	public int getClipCount() {
+		return clipCount;
+	}
+
+	public void setClipCount(int clipCount) {
+		this.clipCount = clipCount;
 	}
 }

core/src/main/java/nl/andrewl/aos_core/model/item/Inventory.java

@@ -25,13 +25,17 @@ public class Inventory {
 		return itemStacks;
 	}
 
+	public int getSelectedIndex() {
+		return selectedIndex;
+	}
+
 	public ItemStack getSelectedItemStack() {
 		return itemStacks.get(selectedIndex);
 	}
 
 	public void setSelectedIndex(int newIndex) {
-		while (newIndex < 0) newIndex += itemStacks.size();
+		if (newIndex < 0) newIndex = 0;
-		while (newIndex > itemStacks.size() - 1) newIndex -= itemStacks.size();
+		if (newIndex > itemStacks.size() - 1) newIndex = itemStacks.size() - 1;
 		this.selectedIndex = newIndex;
 	}
 }

core/src/main/java/nl/andrewl/aos_core/model/item/ItemStack.java

@@ -1,5 +1,10 @@
 package nl.andrewl.aos_core.model.item;
 
+import nl.andrewl.record_net.util.ExtendedDataInputStream;
+import nl.andrewl.record_net.util.ExtendedDataOutputStream;
+
+import java.io.IOException;
+
 /**
  * Represents a stack of items in the player's inventory. This is generally
  * a type of item, and the amount of it.
@@ -22,6 +27,53 @@ public class ItemStack {
 	}
 
 	public void setAmount(int amount) {
-		this.amount = amount;
+		if (amount > -1) {
+			this.amount = amount;
+		}
+	}
+
+	public void incrementAmount() {
+		setAmount(amount + 1);
+	}
+
+	public void decrementAmount() {
+		setAmount(amount - 1);
+	}
+
+	public static int byteSize(ItemStack stack) {
+		int bytes = 2 * Integer.BYTES;
+		if (stack instanceof BlockItemStack) {
+			bytes += Byte.BYTES;
+		} else if (stack instanceof GunItemStack) {
+			bytes += 2 * Integer.BYTES;
+		}
+		return bytes;
+	}
+
+	public static void write(ItemStack stack, ExtendedDataOutputStream out) throws IOException {
+		out.writeInt(stack.type.id);
+		out.writeInt(stack.amount);
+		if (stack instanceof BlockItemStack b) {
+			out.writeByte(b.getSelectedValue());
+		} else if (stack instanceof GunItemStack g) {
+			out.writeInt(g.getClipCount());
+			out.writeInt(g.getBulletCount());
+		}
+	}
+
+	public static ItemStack read(ExtendedDataInputStream in) throws IOException {
+		int typeId = in.readInt();
+		Item item = ItemTypes.get(typeId);
+		int amount = in.readInt();
+		if (item instanceof Gun g) {
+			int clipCount = in.readInt();
+			int bulletCount = in.readInt();
+			return new GunItemStack(g, bulletCount, clipCount);
+		} else if (item instanceof BlockItem b) {
+			byte selectedValue = in.readByte();
+			return new BlockItemStack(b, amount, selectedValue);
+		} else {
+			throw new IOException("Invalid item stack.");
+		}
 	}
 }

core/src/main/java/nl/andrewl/aos_core/model/item/ItemTypes.java

@@ -12,9 +12,12 @@ public final class ItemTypes {
 	private static final Map<Integer, Item> TYPES_BY_ID = new HashMap<>();
 	private static final Map<String, Item> TYPES_BY_NAME = new HashMap<>();
 
+	public static final BlockItem BLOCK = new BlockItem(1);
+	public static final Rifle RIFLE = new Rifle(2);
+
 	static {
-		registerType(new BlockItem(1));
+		registerType(BLOCK);
-		registerType(new Rifle(2));
+		registerType(RIFLE);
 	}
 
 	public static void registerType(Item type) {

core/src/main/java/nl/andrewl/aos_core/net/client/ClientInputState.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net.udp;
+package nl.andrewl.aos_core.net.client;
 
 import nl.andrewl.record_net.Message;
 
@@ -19,5 +19,6 @@ public record ClientInputState(
 
 		// Interaction
 		boolean hitting, // Usually a "left-click" action.
-		boolean interacting // Usually a "right-click" action.
+		boolean interacting, // Usually a "right-click" action.
+		int selectedInventoryIndex // The selected index in the player's inventory.
 ) implements Message {}

core/src/main/java/nl/andrewl/aos_core/net/client/ClientInventoryMessage.java

@@ -0,0 +1,15 @@
+package nl.andrewl.aos_core.net.client;
+
+import nl.andrewl.aos_core.model.item.Inventory;
+import nl.andrewl.record_net.Message;
+
+/**
+ * A message that's sent by the server to a client with information about the
+ * client's full inventory configuration. Here, we use a custom serializer
+ * since the inventory object contains a lot of inheritance.
+ *
+ * @see InventorySerializer
+ */
+public record ClientInventoryMessage(
+		Inventory inv
+) implements Message {}

core/src/main/java/nl/andrewl/aos_core/net/client/ClientOrientationState.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net.udp;
+package nl.andrewl.aos_core.net.client;
 
 import nl.andrewl.record_net.Message;
 

core/src/main/java/nl/andrewl/aos_core/net/client/InventorySelectedStackMessage.java

@@ -0,0 +1,11 @@
+package nl.andrewl.aos_core.net.client;
+
+import nl.andrewl.record_net.Message;
+
+/**
+ * A message that's sent when a player's selected inventory stack changes.
+ * @param index The selected index.
+ */
+public record InventorySelectedStackMessage(
+		int index
+) implements Message {}

core/src/main/java/nl/andrewl/aos_core/net/client/InventorySerializer.java

@@ -0,0 +1,56 @@
+package nl.andrewl.aos_core.net.client;
+
+import nl.andrewl.aos_core.model.item.Inventory;
+import nl.andrewl.aos_core.model.item.ItemStack;
+import nl.andrewl.record_net.MessageReader;
+import nl.andrewl.record_net.MessageTypeSerializer;
+import nl.andrewl.record_net.MessageWriter;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Function;
+
+public class InventorySerializer implements MessageTypeSerializer<ClientInventoryMessage> {
+	@Override
+	public Class<ClientInventoryMessage> messageClass() {
+		return ClientInventoryMessage.class;
+	}
+
+	@Override
+	public Function<ClientInventoryMessage, Integer> byteSizeFunction() {
+		return msg -> {
+			int bytes = Integer.BYTES; // For the stack count size.
+			for (var stack : msg.inv().getItemStacks()) {
+				bytes += ItemStack.byteSize(stack);
+			}
+			bytes += Integer.BYTES; // Selected index.
+			return bytes;
+		};
+	}
+
+	@Override
+	public MessageReader<ClientInventoryMessage> reader() {
+		return in -> {
+			int stacksCount = in.readInt();
+			List<ItemStack> stacks = new ArrayList<>(stacksCount);
+			for (int i = 0; i < stacksCount; i++) {
+				stacks.add(ItemStack.read(in));
+			}
+			int selectedIndex = in.readInt();
+			Inventory inv = new Inventory(stacks, selectedIndex);
+			return new ClientInventoryMessage(inv);
+		};
+	}
+
+	@Override
+	public MessageWriter<ClientInventoryMessage> writer() {
+		return (msg, out) -> {
+			Inventory inv = msg.inv();
+			out.writeInt(inv.getItemStacks().size());
+			for (var stack : inv.getItemStacks()) {
+				ItemStack.write(stack, out);
+			}
+			out.writeInt(inv.getSelectedIndex());
+		};
+	}
+}

core/src/main/java/nl/andrewl/aos_core/net/client/ItemStackMessage.java

@@ -0,0 +1,18 @@
+package nl.andrewl.aos_core.net.client;
+
+import nl.andrewl.aos_core.model.item.Inventory;
+import nl.andrewl.aos_core.model.item.ItemStack;
+import nl.andrewl.record_net.Message;
+
+/**
+ * Lightweight packet that's sent when a single item stack in a player's
+ * inventory updates.
+ */
+public record ItemStackMessage(
+		int index,
+		ItemStack stack
+) implements Message {
+	public ItemStackMessage(Inventory inv) {
+		this(inv.getSelectedIndex(), inv.getSelectedItemStack());
+	}
+}

core/src/main/java/nl/andrewl/aos_core/net/client/ItemStackSerializer.java

@@ -0,0 +1,37 @@
+package nl.andrewl.aos_core.net.client;
+
+import nl.andrewl.aos_core.model.item.ItemStack;
+import nl.andrewl.record_net.MessageReader;
+import nl.andrewl.record_net.MessageTypeSerializer;
+import nl.andrewl.record_net.MessageWriter;
+
+import java.util.function.Function;
+
+public class ItemStackSerializer implements MessageTypeSerializer<ItemStackMessage> {
+	@Override
+	public Class<ItemStackMessage> messageClass() {
+		return ItemStackMessage.class;
+	}
+
+	@Override
+	public Function<ItemStackMessage, Integer> byteSizeFunction() {
+		return msg -> Integer.BYTES + ItemStack.byteSize(msg.stack());
+	}
+
+	@Override
+	public MessageReader<ItemStackMessage> reader() {
+		return in -> {
+			int index = in.readInt();
+			ItemStack stack = ItemStack.read(in);
+			return new ItemStackMessage(index, stack);
+		};
+	}
+
+	@Override
+	public MessageWriter<ItemStackMessage> writer() {
+		return (msg, out) -> {
+			out.writeInt(msg.index());
+			ItemStack.write(msg.stack(), out);
+		};
+	}
+}

core/src/main/java/nl/andrewl/aos_core/net/client/PlayerJoinMessage.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net;
+package nl.andrewl.aos_core.net.client;
 
 import nl.andrewl.aos_core.model.Player;
 import nl.andrewl.record_net.Message;

core/src/main/java/nl/andrewl/aos_core/net/client/PlayerLeaveMessage.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net;
+package nl.andrewl.aos_core.net.client;
 
 import nl.andrewl.record_net.Message;
 

core/src/main/java/nl/andrewl/aos_core/net/client/PlayerUpdateMessage.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net.udp;
+package nl.andrewl.aos_core.net.client;
 
 import nl.andrewl.aos_core.model.Player;
 import nl.andrewl.record_net.Message;

core/src/main/java/nl/andrewl/aos_core/net/connect/ConnectAcceptMessage.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net;
+package nl.andrewl.aos_core.net.connect;
 
 import nl.andrewl.record_net.Message;
 

core/src/main/java/nl/andrewl/aos_core/net/connect/ConnectRejectMessage.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net;
+package nl.andrewl.aos_core.net.connect;
 
 import nl.andrewl.record_net.Message;
 

core/src/main/java/nl/andrewl/aos_core/net/connect/ConnectRequestMessage.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net;
+package nl.andrewl.aos_core.net.connect;
 
 import nl.andrewl.record_net.Message;
 

core/src/main/java/nl/andrewl/aos_core/net/connect/DatagramInit.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net.udp;
+package nl.andrewl.aos_core.net.connect;
 
 import nl.andrewl.record_net.Message;
 

core/src/main/java/nl/andrewl/aos_core/net/world/ChunkDataMessage.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net;
+package nl.andrewl.aos_core.net.world;
 
 import nl.andrewl.aos_core.model.world.Chunk;
 import nl.andrewl.record_net.Message;

core/src/main/java/nl/andrewl/aos_core/net/world/ChunkHashMessage.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net;
+package nl.andrewl.aos_core.net.world;
 
 import nl.andrewl.aos_core.model.world.Chunk;
 import nl.andrewl.record_net.Message;

core/src/main/java/nl/andrewl/aos_core/net/world/ChunkUpdateMessage.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net.udp;
+package nl.andrewl.aos_core.net.world;
 
 import nl.andrewl.aos_core.model.world.World;
 import nl.andrewl.record_net.Message;

core/src/main/java/nl/andrewl/aos_core/net/world/WorldInfoMessage.java

@@ -1,4 +1,4 @@
-package nl.andrewl.aos_core.net;
+package nl.andrewl.aos_core.net.world;
 
 import nl.andrewl.aos_core.model.world.World;
 import nl.andrewl.record_net.Message;

server/src/main/java/nl/andrewl/aos2_server/ClientCommunicationHandler.java

@@ -3,6 +3,14 @@ package nl.andrewl.aos2_server;
 import nl.andrewl.aos_core.Net;
 import nl.andrewl.aos_core.model.world.Chunk;
 import nl.andrewl.aos_core.net.*;
+import nl.andrewl.aos_core.net.client.PlayerJoinMessage;
+import nl.andrewl.aos_core.net.connect.ConnectAcceptMessage;
+import nl.andrewl.aos_core.net.connect.ConnectRejectMessage;
+import nl.andrewl.aos_core.net.connect.ConnectRequestMessage;
+import nl.andrewl.aos_core.net.client.ClientInventoryMessage;
+import nl.andrewl.aos_core.net.world.ChunkDataMessage;
+import nl.andrewl.aos_core.net.world.ChunkHashMessage;
+import nl.andrewl.aos_core.net.world.WorldInfoMessage;
 import nl.andrewl.record_net.Message;
 import nl.andrewl.record_net.util.ExtendedDataInputStream;
 import nl.andrewl.record_net.util.ExtendedDataOutputStream;
@@ -81,6 +89,7 @@ public class ClientCommunicationHandler {
 			try {
 				Message msg = Net.read(in);
 				if (msg instanceof ConnectRequestMessage connectMsg) {
+					log.debug("Received connect request from player \"{}\"", connectMsg.username());
 					// Try to set the TCP timeout back to 0 now that we've got the correct request.
 					socket.setSoTimeout(0);
 					this.clientAddress = socket.getInetAddress();
@@ -90,7 +99,10 @@ public class ClientCommunicationHandler {
 					log.debug("Sent connect accept message.");
 
 					sendTcpMessage(new WorldInfoMessage(server.getWorld()));
-					// Send join info for all players that are already connected.
+					// Send player's inventory information.
+					sendTcpMessage(new ClientInventoryMessage(player.getInventory()));
+
+					// Send "join" info about all the players that are already connected, so the client is aware of them.
 					for (var player : server.getPlayerManager().getPlayers()) {
 						if (player.getId() != this.player.getId()) {
 							sendTcpMessage(new PlayerJoinMessage(player));

server/src/main/java/nl/andrewl/aos2_server/PlayerManager.java

@@ -1,9 +1,9 @@
 package nl.andrewl.aos2_server;
 
 import nl.andrewl.aos_core.Net;
-import nl.andrewl.aos_core.net.PlayerJoinMessage;
+import nl.andrewl.aos_core.net.client.PlayerJoinMessage;
-import nl.andrewl.aos_core.net.PlayerLeaveMessage;
+import nl.andrewl.aos_core.net.client.PlayerLeaveMessage;
-import nl.andrewl.aos_core.net.udp.DatagramInit;
+import nl.andrewl.aos_core.net.connect.DatagramInit;
 import nl.andrewl.record_net.Message;
 import org.joml.Vector3f;
 import org.slf4j.Logger;

server/src/main/java/nl/andrewl/aos2_server/Server.java

@@ -6,9 +6,9 @@ import nl.andrewl.aos_core.config.Config;
 import nl.andrewl.aos_core.model.world.World;
 import nl.andrewl.aos_core.model.world.Worlds;
 import nl.andrewl.aos_core.net.UdpReceiver;
-import nl.andrewl.aos_core.net.udp.ClientInputState;
+import nl.andrewl.aos_core.net.client.ClientInputState;
-import nl.andrewl.aos_core.net.udp.ClientOrientationState;
+import nl.andrewl.aos_core.net.client.ClientOrientationState;
-import nl.andrewl.aos_core.net.udp.DatagramInit;
+import nl.andrewl.aos_core.net.connect.DatagramInit;
 import nl.andrewl.record_net.Message;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -66,8 +66,9 @@ public class Server implements Runnable {
 		} else if (msg instanceof ClientInputState inputState) {
 			ServerPlayer player = playerManager.getPlayer(inputState.clientId());
 			if (player != null) {
-				player.getActionManager().setLastInputState(inputState);
+				if (player.getActionManager().setLastInputState(inputState)) {
-				playerManager.broadcastUdpMessage(player.getUpdateMessage());
+					playerManager.broadcastUdpMessage(player.getUpdateMessage());
+				}
 			}
 		} else if (msg instanceof ClientOrientationState orientationState) {
 			ServerPlayer player = playerManager.getPlayer(orientationState.clientId());
@@ -86,7 +87,7 @@ public class Server implements Runnable {
 			ForkJoinPool.commonPool().submit(() -> {
 				try {
 					handler.establishConnection();
-				} catch (IOException e) {
+				} catch (Exception e) {
 					e.printStackTrace();
 				}
 			});

server/src/main/java/nl/andrewl/aos2_server/ServerPlayer.java

@@ -2,15 +2,20 @@ package nl.andrewl.aos2_server;
 
 import nl.andrewl.aos2_server.logic.PlayerActionManager;
 import nl.andrewl.aos_core.model.Player;
-import nl.andrewl.aos_core.model.item.*;
+import nl.andrewl.aos_core.model.item.BlockItemStack;
-import nl.andrewl.aos_core.model.item.gun.Rifle;
+import nl.andrewl.aos_core.model.item.GunItemStack;
-import nl.andrewl.aos_core.net.udp.PlayerUpdateMessage;
+import nl.andrewl.aos_core.model.item.Inventory;
+import nl.andrewl.aos_core.model.item.ItemTypes;
+import nl.andrewl.aos_core.net.client.PlayerUpdateMessage;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.util.ArrayList;
-import java.util.List;
 
+/**
+ * An extension of the base player class with additional information that's
+ * needed for the server.
+ */
 public class ServerPlayer extends Player {
 	private static final Logger log = LoggerFactory.getLogger(ServerPlayer.class);
 
@@ -26,16 +31,20 @@ public class ServerPlayer extends Player {
 
 	public ServerPlayer(int id, String username) {
 		super(id, username);
-		this.actionManager = new PlayerActionManager(this);
 		this.inventory = new Inventory(new ArrayList<>(), 0);
+		this.actionManager = new PlayerActionManager(this);
 		inventory.getItemStacks().add(new GunItemStack(ItemTypes.get("Rifle")));
-		inventory.getItemStacks().add(new BlockItemStack(ItemTypes.get("Block"), 50));
+		inventory.getItemStacks().add(new BlockItemStack(ItemTypes.get("Block"), 50, (byte) 1));
 	}
 
 	public PlayerActionManager getActionManager() {
 		return actionManager;
 	}
 
+	public Inventory getInventory() {
+		return inventory;
+	}
+
 	/**
 	 * Helper method to build an update message for this player, to be sent to
 	 * various clients.

server/src/main/java/nl/andrewl/aos2_server/logic/PlayerActionManager.java

@@ -3,9 +3,13 @@ package nl.andrewl.aos2_server.logic;
 import nl.andrewl.aos2_server.Server;
 import nl.andrewl.aos2_server.ServerPlayer;
 import nl.andrewl.aos2_server.config.ServerConfig;
+import nl.andrewl.aos_core.model.item.BlockItemStack;
+import nl.andrewl.aos_core.model.item.ItemTypes;
 import nl.andrewl.aos_core.model.world.World;
-import nl.andrewl.aos_core.net.udp.ChunkUpdateMessage;
+import nl.andrewl.aos_core.net.client.ClientInputState;
-import nl.andrewl.aos_core.net.udp.ClientInputState;
+import nl.andrewl.aos_core.net.client.InventorySelectedStackMessage;
+import nl.andrewl.aos_core.net.client.ItemStackMessage;
+import nl.andrewl.aos_core.net.world.ChunkUpdateMessage;
 import org.joml.Math;
 import org.joml.Vector2i;
 import org.joml.Vector3f;
@@ -30,15 +34,23 @@ public class PlayerActionManager {
 
 	public PlayerActionManager(ServerPlayer player) {
 		this.player = player;
-		lastInputState = new ClientInputState(player.getId(), false, false, false, false, false, false, false, false, false);
+		lastInputState = new ClientInputState(
+				player.getId(),
+				false, false, false, false,
+				false, false, false,
+				false, false,
+				player.getInventory().getSelectedIndex()
+		);
 	}
 
 	public ClientInputState getLastInputState() {
 		return lastInputState;
 	}
 
-	public void setLastInputState(ClientInputState lastInputState) {
+	public boolean setLastInputState(ClientInputState lastInputState) {
-		this.lastInputState = lastInputState;
+		boolean change = !lastInputState.equals(this.lastInputState);
+		if (change) this.lastInputState = lastInputState;
+		return change;
 	}
 
 	public boolean isUpdated() {
@@ -46,36 +58,65 @@ public class PlayerActionManager {
 	}
 
 	public void tick(float dt, World world, Server server) {
+		updated = false; // Reset the updated flag. This will be set to true if the player was updated in this tick.
 		long now = System.currentTimeMillis();
+		if (player.getInventory().getSelectedIndex() != lastInputState.selectedInventoryIndex()) {
+			player.getInventory().setSelectedIndex(lastInputState.selectedInventoryIndex());
+			// Tell the client that their inventory slot has been updated properly.
+			server.getPlayerManager().getHandler(player.getId()).sendDatagramPacket(new InventorySelectedStackMessage(player.getInventory().getSelectedIndex()));
+			updated = true; // Tell everyone else that this player's selected item has changed.
+		}
+
+		if (player.getInventory().getSelectedItemStack().getType().equals(ItemTypes.BLOCK)) {
+			tickBlockAction(now, server, world);
+		}
+
+		tickMovement(dt, world, server.getConfig().physics);
+	}
+
+	private void tickBlockAction(long now, Server server, World world) {
+		BlockItemStack stack = (BlockItemStack) player.getInventory().getSelectedItemStack();
 		// Check for breaking blocks.
-		if (lastInputState.hitting() && now - lastBlockRemovedAt > server.getConfig().actions.blockRemoveCooldown * 1000) {
+		if (
+				lastInputState.hitting() &&
+				stack.getAmount() < stack.getType().getMaxAmount() &&
+				now - lastBlockRemovedAt > server.getConfig().actions.blockRemoveCooldown * 1000
+		) {
 			Vector3f eyePos = new Vector3f(player.getPosition());
 			eyePos.y += getEyeHeight();
 			var hit = world.getLookingAtPos(eyePos, player.getViewVector(), 10);
 			if (hit != null) {
 				world.setBlockAt(hit.pos().x, hit.pos().y, hit.pos().z, (byte) 0);
 				lastBlockRemovedAt = now;
+				stack.incrementAmount();
+				server.getPlayerManager().getHandler(player.getId()).sendDatagramPacket(new ItemStackMessage(player.getInventory()));
 				server.getPlayerManager().broadcastUdpMessage(ChunkUpdateMessage.fromWorld(hit.pos(), world));
 			}
 		}
 		// Check for placing blocks.
-		if (lastInputState.interacting() && now - lastBlockPlacedAt > server.getConfig().actions.blockPlaceCooldown * 1000) {
+		if (
+				lastInputState.interacting() &&
+				stack.getAmount() > 0 &&
+				now - lastBlockPlacedAt > server.getConfig().actions.blockPlaceCooldown * 1000
+		) {
 			Vector3f eyePos = new Vector3f(player.getPosition());
 			eyePos.y += getEyeHeight();
 			var hit = world.getLookingAtPos(eyePos, player.getViewVector(), 10);
 			if (hit != null) {
 				Vector3i placePos = new Vector3i(hit.pos());
 				placePos.add(hit.norm());
-				world.setBlockAt(placePos.x, placePos.y, placePos.z, (byte) 1);
+				if (!isSpaceOccupied(placePos)) { // Ensure that we can't place blocks in space we're occupying.
-				lastBlockPlacedAt = now;
+					world.setBlockAt(placePos.x, placePos.y, placePos.z, stack.getSelectedValue());
-				server.getPlayerManager().broadcastUdpMessage(ChunkUpdateMessage.fromWorld(placePos, world));
+					lastBlockPlacedAt = now;
+					stack.decrementAmount();
+					server.getPlayerManager().getHandler(player.getId()).sendDatagramPacket(new ItemStackMessage(player.getInventory()));
+					server.getPlayerManager().broadcastUdpMessage(ChunkUpdateMessage.fromWorld(placePos, world));
+				}
 			}
 		}
-		tickMovement(dt, world, server.getConfig().physics);
 	}
 
 	private void tickMovement(float dt, World world, ServerConfig.PhysicsConfig config) {
-		updated = false; // Reset the updated flag. This will be set to true if the player was updated in this tick.
 		var velocity = player.getVelocity();
 		var position = player.getPosition();
 		boolean grounded = isGrounded(world);
@@ -178,15 +219,30 @@ public class PlayerActionManager {
 		return points;
 	}
 
+	private boolean isSpaceOccupied(Vector3i pos) {
+		var playerPos = player.getPosition();
+		float playerBodyMinZ = playerPos.z - RADIUS;
+		float playerBodyMaxZ = playerPos.z + RADIUS;
+		float playerBodyMinX = playerPos.x - RADIUS;
+		float playerBodyMaxX = playerPos.x + RADIUS;
+		float playerBodyMinY = playerPos.y;
+		float playerBodyMaxY = playerPos.y + getCurrentHeight();
+
+		// Compute the bounds of all blocks the player is intersecting with.
+		int minX = (int) Math.floor(playerBodyMinX);
+		int minZ = (int) Math.floor(playerBodyMinZ);
+		int minY = (int) Math.floor(playerBodyMinY);
+		int maxX = (int) Math.floor(playerBodyMaxX);
+		int maxZ = (int) Math.floor(playerBodyMaxZ);
+		int maxY = (int) Math.floor(playerBodyMaxY);
+
+		return pos.x >= minX && pos.x <= maxX && pos.y >= minY && pos.y <= maxY && pos.z >= minZ && pos.z <= maxZ;
+	}
+
 	private void checkBlockCollisions(Vector3f movement, World world) {
 		var position = player.getPosition();
 		var velocity = player.getVelocity();
 		final Vector3f nextTickPosition = new Vector3f(position).add(movement);
-//		System.out.printf("Pos:\t\t%.3f, %.3f, %.3f%nmov:\t\t%.3f, %.3f, %.3f%nNexttick:\t%.3f, %.3f, %.3f%n",
-//				position.x, position.y, position.z,
-//				movement.x, movement.y, movement.z,
-//				nextTickPosition.x, nextTickPosition.y, nextTickPosition.z
-//		);
 		float height = getCurrentHeight();
 		float delta = 0.00001f;
 		final Vector3f stepSize = new Vector3f(movement).normalize(1.0f);
@@ -205,7 +261,6 @@ public class PlayerActionManager {
 
 			// Check if we collide with anything at this new position.
 
-
 			float playerBodyPrevMinZ = lastPos.z - RADIUS;
 			float playerBodyPrevMaxZ = lastPos.z + RADIUS;
 			float playerBodyPrevMinX = lastPos.x - RADIUS;