bot physics complete

LICENSE

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+MIT License
+
+Copyright (c) 2021 batchprogrammer314
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

PlayerAI.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" name="spigot" level="project" />
+  </component>
+</module>

src/net/nuggetmc/ai/PlayerAI.java

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+package net.nuggetmc.ai;
+
+import net.nuggetmc.ai.cmd.CommandHandler;
+import net.nuggetmc.ai.cmd.CommandInterface;
+import net.nuggetmc.ai.cmd.commands.CreateCommand;
+import net.nuggetmc.ai.cmd.commands.DebugCommand;
+import net.nuggetmc.ai.cmd.commands.InfoCommand;
+import net.nuggetmc.ai.cmd.commands.ResetCommand;
+import net.nuggetmc.ai.npc.NPCManager;
+import org.bukkit.command.PluginCommand;
+import org.bukkit.plugin.java.JavaPlugin;
+
+public class PlayerAI extends JavaPlugin {
+
+    private static PlayerAI instance;
+
+    private final CommandHandler HANDLER;
+    private final NPCManager MANAGER;
+
+    public PlayerAI() {
+        instance = this;
+
+        this.HANDLER = new CommandHandler();
+        this.MANAGER = new NPCManager(this);
+    }
+
+    public static PlayerAI getInstance() {
+        return instance;
+    }
+
+    public CommandHandler getHandler() {
+        return HANDLER;
+    }
+
+    public NPCManager getManager() {
+        return MANAGER;
+    }
+
+    @Override
+    public void onEnable() {
+        getServer().getPluginManager().registerEvents(MANAGER, this);
+        registerCommands();
+
+        MANAGER.connectAll();
+    }
+
+    @Override
+    public void onDisable() {
+        MANAGER.reset();
+        MANAGER.disconnectAll();
+    }
+
+    private void registerCommands() {
+        HANDLER.register(new CommandInterface[] {
+            new CreateCommand(),
+            new InfoCommand(),
+            new DebugCommand(),
+            new ResetCommand()
+        });
+
+        PluginCommand command = getCommand("playerai");
+
+        if (command != null) {
+            command.setExecutor(HANDLER);
+            command.setTabCompleter(HANDLER);
+        }
+    }
+}

src/net/nuggetmc/ai/cmd/CommandHandler.java

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+package net.nuggetmc.ai.cmd;
+
+import net.md_5.bungee.api.ChatColor;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandExecutor;
+import org.bukkit.command.CommandSender;
+import org.bukkit.command.TabCompleter;
+
+import java.util.*;
+
+public class CommandHandler implements CommandExecutor, TabCompleter {
+
+    private final Map<String, CommandInterface> COMMANDS = new HashMap<>();
+
+    private final String PREFIX = "bot";
+
+    public void register(CommandInterface[] subCmds) {
+        for (CommandInterface cmd : subCmds) {
+            COMMANDS.put(cmd.getName(), cmd);
+        }
+    }
+
+    public String fetchName(CommandInterface subCmd) {
+        String name = subCmd.getClass().getSimpleName();
+        return name.substring(0, name.length() - 7).toLowerCase();
+    }
+
+    private boolean exists(String name) {
+        return COMMANDS.containsKey(name.toLowerCase());
+    }
+
+    private CommandInterface getExecutor(String name) {
+        return COMMANDS.get(name.toLowerCase());
+    }
+
+    public String nonPlayerMsg() {
+        return ChatColor.RED + "You must be a player to execute this command!";
+    }
+
+    public String usageMsg(CommandInterface subCmd) {
+        return ChatColor.RED + "Invalid arguments!\nUsage: /" + PREFIX + " " + subCmd.getName() + " " + subCmd.getUsage();
+    }
+
+    private void sendCmdInfo(CommandSender sender) {
+        sender.sendMessage(ChatColor.GRAY + "----------------------------------------");
+
+        sender.sendMessage(ChatColor.GOLD + "PlayerAI" + ChatColor.GRAY + " [" + ChatColor.RED + "v1.0" + ChatColor.GRAY + "]");
+
+        for (Map.Entry<String, CommandInterface> entry : COMMANDS.entrySet()) {
+            sender.sendMessage(ChatColor.GRAY + " ▪ " + ChatColor.YELLOW + "/" + PREFIX + " " + entry.getKey() + ChatColor.GRAY + " ▪ "
+                    + ChatColor.RESET +  entry.getValue().getDescription());
+        }
+
+        sender.sendMessage(ChatColor.GRAY + "----------------------------------------");
+    }
+
+    @Override
+    public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {
+        if (args.length == 0 || !exists(args[0])) {
+            sendCmdInfo(sender);
+            return true;
+        }
+
+        getExecutor(args[0]).onCommand(sender, cmd, label, Arrays.copyOfRange(args, 1, args.length));
+        return true;
+    }
+
+    @Override
+    public List<String> onTabComplete(CommandSender sender, Command cmd, String label, String[] args) {
+        if (!cmd.getName().equals("playerai")) return null;
+
+        List<String> groupnames;
+        int n = args.length;
+
+        switch (n) {
+            case 1:
+                groupnames = new ArrayList<>(COMMANDS.keySet());
+                String arg = args[n - 1];
+
+                if (!isEmptyTab(arg)) {
+                    return autofill(groupnames, arg);
+                }
+
+                return groupnames;
+
+            default:
+                return null;
+        }
+    }
+
+    private boolean isEmptyTab(String s) {
+        return s == null || s.equals("") || s.equals(" ") || s.isEmpty();
+    }
+
+    private List<String> autofill(List<String> groupnames, String input) {
+        List<String> list = new ArrayList<>();
+
+        for (String entry : groupnames) {
+            if (entry.length() >= input.length()) {
+                if (input.equalsIgnoreCase(entry.substring(0, input.length()))) {
+                    list.add(entry);
+                }
+            }
+        }
+
+        if (list.isEmpty()) {
+            return groupnames;
+        }
+
+        return list;
+    }
+}

src/net/nuggetmc/ai/cmd/CommandInterface.java

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+package net.nuggetmc.ai.cmd;
+
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+
+public interface CommandInterface {
+    String getName();
+    String getDescription();
+    String getUsage();
+
+    void onCommand(CommandSender sender, Command cmd, String label, String[] args);
+}

src/net/nuggetmc/ai/cmd/commands/CreateCommand.java

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+package net.nuggetmc.ai.cmd.commands;
+
+import net.md_5.bungee.api.ChatColor;
+import net.nuggetmc.ai.PlayerAI;
+import net.nuggetmc.ai.cmd.CommandHandler;
+import net.nuggetmc.ai.cmd.CommandInterface;
+import net.nuggetmc.ai.npc.NPC;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+
+public class CreateCommand implements CommandInterface {
+
+    private final CommandHandler HANDLER;
+
+    private final String NAME;
+    private final String DESCRIPTION = "Create NPCs.";
+    private final String CMD_ARGS = "<name> [skin]";
+
+    public CreateCommand() {
+        this.HANDLER = PlayerAI.getInstance().getHandler();
+        this.NAME = HANDLER.fetchName(this);
+    }
+
+    @Override
+    public String getName() {
+        return NAME;
+    }
+
+    @Override
+    public String getDescription() {
+        return DESCRIPTION;
+    }
+
+    @Override
+    public String getUsage() {
+        return CMD_ARGS;
+    }
+
+    @Override
+    public void onCommand(CommandSender sender, Command cmd, String label, String[] args) {
+        if (!(sender instanceof Player)) {
+            sender.sendMessage(HANDLER.nonPlayerMsg());
+            return;
+        }
+
+        if (args.length == 0) {
+            sender.sendMessage(HANDLER.usageMsg(this));
+            return;
+        }
+
+        String skin;
+
+        if (args.length > 1) {
+            skin = args[1];
+        } else {
+            skin = args[0];
+        }
+
+        Player player = (Player) sender;
+        NPC npc = NPC.createNPC(args[0], player.getLocation(), skin);
+    }
+}

src/net/nuggetmc/ai/cmd/commands/DebugCommand.java

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+package net.nuggetmc.ai.cmd.commands;
+
+import net.nuggetmc.ai.PlayerAI;
+import net.nuggetmc.ai.cmd.CommandHandler;
+import net.nuggetmc.ai.cmd.CommandInterface;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.bukkit.scheduler.BukkitRunnable;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class DebugCommand implements CommandInterface {
+
+    private final CommandHandler HANDLER;
+
+    private final String NAME;
+    private final String DESCRIPTION = "Debug NPC stats.";
+    private final String CMD_ARGS = "";
+
+    public DebugCommand() {
+        this.HANDLER = PlayerAI.getInstance().getHandler();
+        this.NAME = HANDLER.fetchName(this);
+    }
+
+    @Override
+    public String getName() {
+        return NAME;
+    }
+
+    @Override
+    public String getDescription() {
+        return DESCRIPTION;
+    }
+
+    @Override
+    public String getUsage() {
+        return CMD_ARGS;
+    }
+
+    private boolean active = false;
+
+    private Set<BukkitRunnable> tasks = new HashSet<>();
+
+    private double round2Dec(double n) {
+        return Math.round(n * 100) / 100.0;
+    }
+
+    @Override
+    public void onCommand(CommandSender sender, Command cmd, String label, String[] args) {
+    }
+}

src/net/nuggetmc/ai/cmd/commands/InfoCommand.java

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+package net.nuggetmc.ai.cmd.commands;
+
+import net.nuggetmc.ai.PlayerAI;
+import net.nuggetmc.ai.cmd.CommandHandler;
+import net.nuggetmc.ai.cmd.CommandInterface;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+
+public class InfoCommand implements CommandInterface {
+
+    private final CommandHandler HANDLER;
+
+    private final String NAME;
+    private final String DESCRIPTION = "Information about loaded NPCs.";
+    private final String CMD_ARGS = "";
+
+    public InfoCommand() {
+        this.HANDLER = PlayerAI.getInstance().getHandler();
+        this.NAME = HANDLER.fetchName(this);
+    }
+
+    @Override
+    public String getName() {
+        return NAME;
+    }
+
+    @Override
+    public String getDescription() {
+        return DESCRIPTION;
+    }
+
+    @Override
+    public String getUsage() {
+        return CMD_ARGS;
+    }
+
+    @Override
+    public void onCommand(CommandSender sender, Command cmd, String label, String[] args) {
+    }
+}

src/net/nuggetmc/ai/cmd/commands/ResetCommand.java

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+package net.nuggetmc.ai.cmd.commands;
+
+import net.md_5.bungee.api.ChatColor;
+import net.nuggetmc.ai.PlayerAI;
+import net.nuggetmc.ai.cmd.CommandHandler;
+import net.nuggetmc.ai.cmd.CommandInterface;
+import net.nuggetmc.ai.npc.NPCManager;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+
+import java.text.NumberFormat;
+import java.util.Locale;
+
+public class ResetCommand implements CommandInterface {
+
+    private final PlayerAI INSTANCE;
+
+    private final CommandHandler HANDLER;
+    private final NPCManager MANAGER;
+
+    private final String NAME;
+    private final String DESCRIPTION = "Information about loaded NPCs.";
+    private final String CMD_ARGS = "";
+
+    public ResetCommand() {
+        this.INSTANCE = PlayerAI.getInstance();
+        this.HANDLER = INSTANCE.getHandler();
+        this.MANAGER = INSTANCE.getManager();
+        this.NAME = HANDLER.fetchName(this);
+    }
+
+    @Override
+    public String getName() {
+        return NAME;
+    }
+
+    @Override
+    public String getDescription() {
+        return DESCRIPTION;
+    }
+
+    @Override
+    public String getUsage() {
+        return CMD_ARGS;
+    }
+
+    @Override
+    public void onCommand(CommandSender sender, Command cmd, String label, String[] args) {
+        sender.sendMessage("Removing every NPC...");
+        int size = MANAGER.fetch().size();
+
+        MANAGER.reset();
+
+        String en;
+        if (size == 1) {
+            en = "y";
+        } else {
+            en = "ies";
+        }
+
+        String formatted = NumberFormat.getNumberInstance(Locale.US).format(size);
+        sender.sendMessage("Removed " + ChatColor.RED + formatted + ChatColor.RESET + " entit" + en + ".");
+    }
+}

src/net/nuggetmc/ai/npc/NPC.java

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+package net.nuggetmc.ai.npc;
+
+import com.mojang.authlib.GameProfile;
+import com.mojang.authlib.properties.Property;
+import net.minecraft.server.v1_16_R3.*;
+import net.nuggetmc.ai.PlayerAI;
+import net.nuggetmc.ai.utils.MojangAPI;
+import net.nuggetmc.ai.utils.SteveUUID;
+import org.bukkit.Bukkit;
+import org.bukkit.Location;
+import org.bukkit.World;
+import org.bukkit.attribute.Attribute;
+import org.bukkit.craftbukkit.v1_16_R3.CraftServer;
+import org.bukkit.craftbukkit.v1_16_R3.CraftWorld;
+import org.bukkit.craftbukkit.v1_16_R3.entity.CraftEntity;
+import org.bukkit.craftbukkit.v1_16_R3.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+import org.bukkit.util.Vector;
+
+import java.util.UUID;
+
+public class NPC extends EntityPlayer {
+
+    public Vector velocity;
+
+    private byte kbTicks;
+
+    private final double REGEN_AMOUNT = 0.05;
+
+    public NPC(MinecraftServer minecraftServer, WorldServer worldServer, GameProfile profile, PlayerInteractManager manager) {
+        super(minecraftServer, worldServer, profile, manager);
+
+        velocity = new Vector(0, 0, 0);
+        kbTicks = 0;
+    }
+
+    public static NPC createNPC(String name, Location loc, String skin) {
+        MinecraftServer nmsServer = ((CraftServer) Bukkit.getServer()).getServer();
+        WorldServer nmsWorld = ((CraftWorld) loc.getWorld()).getHandle();
+
+        UUID uuid = SteveUUID.generate();
+
+        GameProfile profile = new GameProfile(uuid, name);
+        PlayerInteractManager interactManager = new PlayerInteractManager(nmsWorld);
+
+        if (skin != null) {
+            setSkin(profile, skin);
+        }
+
+        NPC npc = new NPC(nmsServer, nmsWorld, profile, interactManager);
+
+        npc.playerConnection = new PlayerConnection(nmsServer, new NetworkManager(EnumProtocolDirection.CLIENTBOUND), npc);
+        npc.setLocation(loc.getX(), loc.getY(), loc.getZ(), loc.getYaw(), loc.getPitch());
+        npc.getBukkitEntity().setNoDamageTicks(0);
+        nmsWorld.addEntity(npc);
+
+        sendSpawnPackets(npc);
+
+        PlayerAI.getInstance().getManager().add(npc);
+
+        return npc;
+    }
+
+    private static void setSkin(GameProfile profile, String skin) {
+        String[] vals = MojangAPI.getSkin(skin);
+
+        if (vals != null) {
+            profile.getProperties().put("textures", new Property("textures", vals[0], vals[1]));
+        }
+    }
+
+    private static void sendSpawnPackets(NPC npc) {
+        DataWatcher watcher = npc.getDataWatcher();
+        watcher.set(new DataWatcherObject<>(16, DataWatcherRegistry.a), (byte) 0xFF);
+
+        for (Player player : Bukkit.getOnlinePlayers()) {
+            PlayerConnection connection = ((CraftPlayer) player).getHandle().playerConnection;
+            npc.render(connection, false);
+        }
+    }
+
+    public void render(PlayerConnection connection, boolean login) {
+        connection.sendPacket(new PacketPlayOutPlayerInfo(PacketPlayOutPlayerInfo.EnumPlayerInfoAction.ADD_PLAYER, this));
+        connection.sendPacket(new PacketPlayOutNamedEntitySpawn(this));
+        connection.sendPacket(new PacketPlayOutEntityMetadata(this.getId(), this.getDataWatcher(), true));
+        connection.sendPacket(new PacketPlayOutPlayerInfo(PacketPlayOutPlayerInfo.EnumPlayerInfoAction.REMOVE_PLAYER, this));
+
+        PacketPlayOutEntityHeadRotation rotationPacket = new PacketPlayOutEntityHeadRotation(this, (byte) ((this.yaw * 256f) / 360f));
+
+        if (login) {
+            Bukkit.getScheduler().runTaskLater(PlayerAI.getInstance(), () -> connection.sendPacket(rotationPacket), 10);
+        } else {
+            connection.sendPacket(rotationPacket);
+        }
+    }
+
+    public void setVelocity(Vector vector) {
+        this.velocity = vector;
+    }
+
+    public void addVelocity(Vector vector) {
+        this.velocity.add(vector);
+    }
+
+    @Override
+    public void tick() {
+        super.tick();
+
+        if (noDamageTicks > 0) --noDamageTicks;
+        if (kbTicks > 0) --kbTicks;
+
+        Player playerNPC = this.getBukkitEntity();
+        if (playerNPC.isDead()) return;
+
+        double health = playerNPC.getHealth();
+        double maxHealth = playerNPC.getAttribute(Attribute.GENERIC_MAX_HEALTH).getDefaultValue();
+        double amount;
+
+        if (health < maxHealth - REGEN_AMOUNT) {
+            amount = health + REGEN_AMOUNT;
+        } else {
+            amount = maxHealth;
+        }
+
+        playerNPC.setHealth(amount);
+
+        updateLocation();
+    }
+
+    private void updateLocation() {
+        velocity.setY(velocity.getY() - 0.1);
+
+        if (predictGround()) {
+            velocity.setY(0);
+            addFriction();
+        }
+
+        this.move(EnumMoveType.SELF, new Vec3D(velocity.getX(), velocity.getY(), velocity.getZ()));
+    }
+
+    private final double OFFSET = 0.05;
+
+    public boolean predictGround() {
+        double vy = velocity.getY();
+
+        if (vy > 0) {
+            return false;
+        }
+
+        double m = vy / 20.0;
+
+        World world = getBukkitEntity().getWorld();
+        AxisAlignedBB box = getBoundingBox();
+
+        double[] xVals = new double[] {
+            box.minX + OFFSET,
+            box.maxX - OFFSET
+        };
+
+        double[] zVals = new double[] {
+            box.minZ + OFFSET,
+            box.maxZ - OFFSET
+        };
+
+        for (double x : xVals) {
+            for (double z : zVals) {
+                double i = locY();
+
+                for (int n = 0; n < 20; n++) {
+                    Location test = new Location(world, x, i, z);
+
+                    if (test.getBlock().getType().isSolid()) {
+                        return true;
+                    }
+
+                    i += m;
+                }
+            }
+        }
+
+        return false;
+    }
+
+    public void addFriction() {
+        velocity.setX(velocity.getX() * 0.5);
+        velocity.setZ(velocity.getZ() * 0.5);
+    }
+
+    public void despawn() {
+        getBukkitEntity().remove();
+    }
+
+    @Override
+    public void collide(Entity entity) {
+        if (!this.isSameVehicle(entity) && !entity.noclip && !this.noclip) {
+            double d0 = entity.locX() - this.locX();
+            double d1 = entity.locZ() - this.locZ();
+            double d2 = MathHelper.a(d0, d1);
+            if (d2 >= 0.009999999776482582D) {
+                d2 = MathHelper.sqrt(d2);
+                d0 /= d2;
+                d1 /= d2;
+                double d3 = 1.0D / d2;
+                if (d3 > 1.0D) {
+                    d3 = 1.0D;
+                }
+
+                d0 *= d3;
+                d1 *= d3;
+                d0 *= 0.05000000074505806D;
+                d1 *= 0.05000000074505806D;
+                d0 *= 1.0F - this.I;
+                d1 *= 1.0F - this.I;
+
+                if (!this.isVehicle()) {
+                    velocity.add(new Vector(-d0 * 3, 0.0D, -d1 * 3));
+                }
+
+                if (!entity.isVehicle()) {
+                    entity.i(d0, 0.0D, d1);
+                }
+            }
+        }
+    }
+
+    @Override
+    public boolean damageEntity(DamageSource damagesource, float f) {
+        boolean damaged = super.damageEntity(damagesource, f);
+
+        net.minecraft.server.v1_16_R3.Entity attacker = damagesource.getEntity();
+
+        if (damaged && kbTicks == 0 && attacker != null) {
+            Player player = getBukkitEntity();
+            CraftEntity entity = attacker.getBukkitEntity();
+            Location loc1 = player.getLocation();
+            Location loc2 = entity.getLocation();
+
+            kb(player, loc1, loc2);
+        }
+
+        return damaged;
+    }
+
+    private void kb(Player playerNPC, Location loc1, Location loc2) {
+        Vector diff = loc1.toVector().subtract(loc2.toVector()).normalize();
+        diff.multiply(0.25);
+        diff.setY(0.5);
+
+        velocity.add(diff);
+        kbTicks = 10;
+    }
+
+    public void faceLocation(Location loc) {
+        try {
+            CraftPlayer playerNPC = this.getBukkitEntity();
+            Vector dir = loc.toVector().subtract(playerNPC.getLocation().toVector()).normalize();
+            Location facing = playerNPC.getLocation().setDirection(dir);
+            playerNPC.teleport(facing);
+
+            for (Player player : Bukkit.getOnlinePlayers()) {
+                PlayerConnection connection = ((CraftPlayer) player).getHandle().playerConnection;
+                connection.sendPacket(new PacketPlayOutEntityHeadRotation(playerNPC.getHandle(), (byte) (facing.getYaw() * 256 / 360)));
+            }
+
+        } catch (IllegalArgumentException ignored) { }
+    }
+
+    @Override
+    public void playerTick() {
+        if (this.hurtTicks > 0) {
+            this.hurtTicks -= 1;
+        }
+
+        entityBaseTick();
+        tickPotionEffects();
+
+        this.aU = (int) this.aT;
+        this.aL = this.aK;
+        this.lastYaw = this.yaw;
+        this.lastPitch = this.pitch;
+    }
+}

src/net/nuggetmc/ai/npc/NPCManager.java

@@ -0,0 +1,153 @@
+package net.nuggetmc.ai.npc;
+
+import io.netty.channel.*;
+import net.minecraft.server.v1_16_R3.PacketPlayOutEntityMetadata;
+import net.minecraft.server.v1_16_R3.PacketPlayOutNamedEntitySpawn;
+import net.minecraft.server.v1_16_R3.PacketPlayOutPlayerInfo;
+import net.minecraft.server.v1_16_R3.PlayerConnection;
+import net.nuggetmc.ai.PlayerAI;
+import org.bukkit.Bukkit;
+import org.bukkit.craftbukkit.v1_16_R3.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerJoinEvent;
+import org.bukkit.event.player.PlayerQuitEvent;
+
+import java.lang.reflect.Field;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+public class NPCManager implements Listener {
+
+    private PlayerAI plugin;
+
+    private final Set<NPC> NPCS = new HashSet<>();
+    private final Map<Integer, NPC> NPC_CONNECTIONS = new HashMap<>();
+
+    public Set<NPC> fetch() {
+        return NPCS;
+    }
+
+    public void add(NPC npc) {
+        NPCS.add(npc);
+
+        Bukkit.getScheduler().runTaskLater(PlayerAI.getInstance(), () -> {
+            NPC_CONNECTIONS.put(npc.getId(), npc);
+        }, 10);
+    }
+
+    public NPCManager(PlayerAI instance) {
+        plugin = instance;
+    }
+
+    public void reset() {
+        for (NPC npc : NPCS) {
+            npc.despawn();
+        }
+
+        NPCS.clear();
+        NPC_CONNECTIONS.clear();
+    }
+
+    @EventHandler
+    public void onJoin(PlayerJoinEvent event) {
+        PlayerConnection connection = ((CraftPlayer) event.getPlayer()).getHandle().playerConnection;
+
+        for (NPC npc : NPCS) {
+            npc.render(connection, true);
+        }
+
+        injectPlayer(event.getPlayer());
+    }
+
+    public void connectAll() {
+        for (Player player : Bukkit.getOnlinePlayers()) {
+            injectPlayer(player);
+        }
+    }
+
+    @EventHandler
+    public void onQuit(PlayerQuitEvent event) {
+        removePlayer(event.getPlayer());
+    }
+
+    public void disconnectAll() {
+        for (Player player : Bukkit.getOnlinePlayers()) {
+            removePlayer(player);
+        }
+    }
+
+    private void injectPlayer(Player player) {
+        ChannelDuplexHandler channelDuplexHandler = new ChannelDuplexHandler() {
+
+            @Override
+            public void channelRead(ChannelHandlerContext channelHandlerContext, Object packet) throws Exception {
+                super.channelRead(channelHandlerContext, packet);
+            }
+
+            @Override
+            public void write(ChannelHandlerContext channelHandlerContext, Object packet, ChannelPromise channelPromise) throws Exception {
+                if (packet instanceof PacketPlayOutNamedEntitySpawn) {
+                    renderNPC(player, (PacketPlayOutNamedEntitySpawn) packet);
+                }
+
+                super.write(channelHandlerContext, packet, channelPromise);
+            }
+        };
+
+        ChannelPipeline pipeline = ((CraftPlayer) player).getHandle().playerConnection.networkManager.channel.pipeline();
+
+        try {
+            pipeline.addBefore("packet_handler", player.getName(), channelDuplexHandler);
+        } catch (IllegalArgumentException ignore) { }
+    }
+
+    private void renderNPC(Player player, PacketPlayOutNamedEntitySpawn packet) {
+        PlayerConnection connection = ((CraftPlayer) player).getHandle().playerConnection;
+        Field field;
+
+        try {
+            field = packet.getClass().getDeclaredField("a");
+        } catch (NoSuchFieldException e) {
+            return;
+        }
+
+        field.setAccessible(true);
+
+        Object obj;
+
+        try {
+            obj = field.get(packet);
+        } catch (IllegalAccessException e) {
+            return;
+        }
+
+        if (!(obj instanceof Integer)) return;
+        int n = (int) obj;
+
+        NPC npc = NPC_CONNECTIONS.get(n);
+        if (npc == null) return;
+
+        connection.sendPacket(new PacketPlayOutPlayerInfo(PacketPlayOutPlayerInfo.EnumPlayerInfoAction.ADD_PLAYER, npc));
+        connection.sendPacket(new PacketPlayOutEntityMetadata(npc.getId(), npc.getDataWatcher(), true));
+
+        PacketPlayOutPlayerInfo noTabPacket = new PacketPlayOutPlayerInfo(PacketPlayOutPlayerInfo.EnumPlayerInfoAction.REMOVE_PLAYER, npc);
+
+        Bukkit.getScheduler().runTaskLater(plugin, () -> {
+            if (!connection.isDisconnected()) {
+                connection.sendPacket(noTabPacket);
+            }
+        }, 5);
+    }
+
+    public void removePlayer(Player player) {
+        Channel channel = ((CraftPlayer) player).getHandle().playerConnection.networkManager.channel;
+        channel.eventLoop().submit(() -> {
+            channel.pipeline().remove(player.getName());
+            return null;
+        });
+    }
+}

src/net/nuggetmc/ai/utils/MojangAPI.java

@@ -0,0 +1,28 @@
+package net.nuggetmc.ai.utils;
+
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+
+import java.io.InputStreamReader;
+import java.net.URL;
+
+public class MojangAPI {
+
+    public static String[] getSkin(String name) {
+        try {
+            URL url = new URL("https://api.mojang.com/users/profiles/minecraft/" + name);
+            InputStreamReader reader = new InputStreamReader(url.openStream());
+            String uuid = new JsonParser().parse(reader).getAsJsonObject().get("id").getAsString();
+
+            URL url2 = new URL("https://sessionserver.mojang.com/session/minecraft/profile/" + uuid + "?unsigned=false");
+            InputStreamReader reader2 = new InputStreamReader(url2.openStream());
+            JsonObject property = new JsonParser().parse(reader2).getAsJsonObject().get("properties").getAsJsonArray().get(0).getAsJsonObject();
+            String texture = property.get("value").getAsString();
+            String signature = property.get("signature").getAsString();
+
+            return new String[] {texture, signature};
+        } catch (Exception e) {
+            return null;
+        }
+    }
+}

src/net/nuggetmc/ai/utils/SteveUUID.java

@@ -0,0 +1,16 @@
+package net.nuggetmc.ai.utils;
+
+import java.util.UUID;
+
+public class SteveUUID {
+
+    public static UUID generate() {
+        UUID uuid = UUID.randomUUID();
+
+        if (uuid.hashCode() % 2 == 0) {
+            return uuid;
+        }
+
+        return generate();
+    }
+}

src/plugin.yml

@@ -0,0 +1,20 @@
+name: PlayerAI
+main: net.nuggetmc.ai.PlayerAI
+version: 1.0
+api-version: 1.16
+author: HorseNuggets
+commands:
+  playerai:
+    description: The PlayerAI base command.
+    permission: playerai.manage
+    usage: /playerai
+    aliases: [bot, pai, ai]
+permissions:
+  playerai.*:
+    description: PlayerAI parent permission.
+    default: op
+    children:
+      playerai.manage: true
+  playerai.manage:
+    description: Allows for PlayerAI NPC management.
+    default: op