bareiron/src/procedures.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "globals.h"
#include "tools.h"
#include "packets.h"
#include "registries.h"
#include "worldgen.h"

int client_states[MAX_PLAYERS * 2];

void setClientState (int client_fd, int new_state) {
  // Look for a client state with a matching file descriptor
  for (int i = 0; i < MAX_PLAYERS * 2; i += 2) {
    if (client_states[i] != client_fd) continue;
    client_states[i + 1] = new_state;
    return;
  }
  // If the above failed, look for an unused client state slot
  for (int i = 0; i < MAX_PLAYERS * 2; i += 2) {
    if (client_states[i] != -1) continue;
    client_states[i] = client_fd;
    client_states[i + 1] = new_state;
    return;
  }
}

int getClientState (int client_fd) {
  for (int i = 0; i < MAX_PLAYERS * 2; i += 2) {
    if (client_states[i] != client_fd) continue;
    return client_states[i + 1];
  }
  return STATE_NONE;
}

int getClientIndex (int client_fd) {
  for (int i = 0; i < MAX_PLAYERS * 2; i += 2) {
    if (client_states[i] != client_fd) continue;
    return i;
  }
  return -1;
}

void resetPlayerData (PlayerData *player) {
  player->health = 20;
  player->hunger = 20;
  player->x = 8;
  player->z = 8;
  player->y = -32767;
  player->grounded_y = 0;
  for (int i = 0; i < 41; i ++) {
    player->inventory_items[i] = 0;
    player->inventory_count[i] = 0;
  }
  for (int i = 0; i < 9; i ++) {
    player->craft_items[i] = 0;
    player->craft_count[i] = 0;
  }
}

int reservePlayerData (int client_fd, uint8_t *uuid, char *name) {

  for (int i = 0; i < MAX_PLAYERS; i ++) {
    if (memcmp(player_data[i].uuid, uuid, 16) == 0) {
      player_data[i].client_fd = client_fd;
      memcpy(player_data[i].name, name, 16);
      return 0;
    }
    uint8_t empty = true;
    for (uint8_t j = 0; j < 16; j ++) {
      if (player_data[i].uuid[j] != 0) {
        empty = false;
        break;
      }
    }
    if (empty) {
      player_data[i].client_fd = client_fd;
      memcpy(player_data[i].uuid, uuid, 16);
      memcpy(player_data[i].name, name, 16);
      resetPlayerData(&player_data[i]);
      return 0;
    }
  }

  return 1;

}

int getPlayerData (int client_fd, PlayerData **output) {
  for (int i = 0; i < MAX_PLAYERS; i ++) {
    if (player_data[i].client_fd == client_fd) {
      *output = &player_data[i];
      return 0;
    }
  }
  return 1;
}

void clearPlayerFD (int client_fd) {
  for (int i = 0; i < MAX_PLAYERS; i ++) {
    if (player_data[i].client_fd == client_fd) {
      player_data[i].client_fd = -1;
      return;
    }
  }
}

uint8_t serverSlotToClientSlot (int window_id, uint8_t slot) {

  if (window_id == 0) { // player inventory

    if (slot < 9) return slot + 36;
    if (slot >= 9 && slot <= 35) return slot;
    if (slot == 40) return 45;
    if (slot >= 36 && slot <= 39) return 3 - (slot - 36) + 5;
    if (slot >= 41 && slot <= 44) return slot - 40;

  } else if (window_id == 12) { // crafting table

    if (slot >= 41 && slot <= 49) return slot - 40;
    return serverSlotToClientSlot(0, slot - 1);

  } else if (window_id == 14) { // furnace

    if (slot >= 41 && slot <= 43) return slot - 41;
    return serverSlotToClientSlot(0, slot + 6);

  }

  return 255;
}

uint8_t clientSlotToServerSlot (int window_id, uint8_t slot) {

  if (window_id == 0) { // player inventory

    if (slot >= 36 && slot <= 44) return slot - 36;
    if (slot >= 9 && slot <= 35) return slot;
    if (slot == 45) return 40;
    if (slot >= 5 && slot <= 8) return 4 - (slot - 5) + 36;

    // map inventory crafting slots to player data crafting grid (semi-hack)
    // this abuses the fact that the buffers are adjacent in player data
    if (slot == 1) return 41;
    if (slot == 2) return 42;
    if (slot == 3) return 44;
    if (slot == 4) return 45;

  } else if (window_id == 12) { // crafting table

    // same crafting offset overflow hack as above
    if (slot >= 1 && slot <= 9) return 40 + slot;
    // the rest of the slots are identical, just shifted by one
    if (slot >= 10 && slot <= 45) return clientSlotToServerSlot(0, slot - 1);

  } else if (window_id == 14) { // furnace

    // move furnace items to the player's crafting grid
    // this lets us put them back in the inventory once the window closes
    if (slot <= 2) return 41 + slot;
    // the rest of the slots are identical, just shifted by 6
    if (slot >= 3 && slot <= 38) return clientSlotToServerSlot(0, slot + 6);

  }

  return 255;
}

int givePlayerItem (PlayerData *player, uint16_t item, uint8_t count) {

  uint8_t slot = 255;
  for (int i = 0; i < 41; i ++) {
    if (player->inventory_items[i] == item && player->inventory_count[i] <= 64 - count) {
      slot = i;
      break;
    }
  }

  if (slot == 255) {
    for (int i = 0; i < 41; i ++) {
      if (player->inventory_count[i] == 0) {
        slot = i;
        break;
      }
    }
  }

  if (slot == 255) return 1;

  player->inventory_items[slot] = item;
  player->inventory_count[slot] += count;
  sc_setContainerSlot(player->client_fd, 0, serverSlotToClientSlot(0, slot), player->inventory_count[slot], item);

  return 0;

}

// Sends the full sequence for spawning the player to the client
void spawnPlayer (PlayerData *player) {

  // Player spawn coordinates, initialized to placeholders
  float spawn_x = 8.5f, spawn_y = 80.0f, spawn_z = 8.5f;
  float spawn_yaw = 0.0f, spawn_pitch = 0.0f;

  if (player->y == -32767) { // Is this a new player?
    // Determine spawning Y coordinate based on terrain height
    spawn_y = getHeightAt(8, 8) + 1;
  } else { // Not a new player
    // Calculate spawn position from player data
    spawn_x = player->x > 0 ? (float)player->x + 0.5 : (float)player->x - 0.5;
    spawn_y = player->y;
    spawn_z = player->z > 0 ? (float)player->z + 0.5 : (float)player->z - 0.5;
    spawn_yaw = player->yaw * 180 / 127;
    spawn_pitch = player->pitch * 90 / 127;
  }

  // Teleport player to spawn coordinates (first pass)
  sc_synchronizePlayerPosition(player->client_fd, spawn_x, spawn_y, spawn_z, spawn_yaw, spawn_pitch);

  task_yield(); // Check task timer between packets

  // Sync client inventory and hotbar
  for (uint8_t i = 0; i < 41; i ++) {
    sc_setContainerSlot(player->client_fd, 0, serverSlotToClientSlot(0, i), player->inventory_count[i], player->inventory_items[i]);
  }
  sc_setHeldItem(player->client_fd, player->hotbar);
  // Sync client health and hunger
  sc_setHealth(player->client_fd, player->health, player->hunger);
  // Sync client clock time
  sc_updateTime(player->client_fd, world_time);

  // Give the player flight (for testing)
  sc_playerAbilities(player->client_fd, 0x04);

  // Calculate player's chunk coordinates
  short _x = div_floor(player->x, 16), _z = div_floor(player->z, 16);

  // Indicate that we're about to send chunk data
  sc_setDefaultSpawnPosition(player->client_fd, 8, 80, 8);
  sc_startWaitingForChunks(player->client_fd);
  sc_setCenterChunk(player->client_fd, _x, _z);

  task_yield(); // Check task timer between packets

  // Send spawn chunk first
  sc_chunkDataAndUpdateLight(player->client_fd, _x, _z);
  for (int i = -VIEW_DISTANCE; i <= VIEW_DISTANCE; i ++) {
    for (int j = -VIEW_DISTANCE; j <= VIEW_DISTANCE; j ++) {
      if (i == 0 && j == 0) continue;
      sc_chunkDataAndUpdateLight(player->client_fd, _x + i, _z + j);
    }
  }
  // Re-teleport player after all chunks have been sent
  sc_synchronizePlayerPosition(player->client_fd, spawn_x, spawn_y, spawn_z, spawn_yaw, spawn_pitch);

  task_yield(); // Check task timer between packets

}

uint8_t getBlockChange (short x, uint8_t y, short z) {
  for (int i = 0; i < block_changes_count; i ++) {
    if (block_changes[i].block == 0xFF) continue;
    if (
      block_changes[i].x == x &&
      block_changes[i].y == y &&
      block_changes[i].z == z
    ) return block_changes[i].block;
  }
  return 0xFF;
}

void makeBlockChange (short x, uint8_t y, short z, uint8_t block) {

  // Transmit block update to all in-game clients
  for (int i = 0; i < MAX_PLAYERS; i ++) {
    if (player_data[i].client_fd == -1) continue;
    if (getClientState(player_data[i].client_fd) != STATE_PLAY) continue;
    sc_blockUpdate(player_data[i].client_fd, x, y, z, block);
  }

  // Calculate terrain at these coordinates and compare it to the input block.
  // Since block changes get overlayed on top of terrain, we don't want to
  // store blocks that don't differ from the base terrain.
  ChunkAnchor anchor = {
    x / CHUNK_SIZE,
    z / CHUNK_SIZE
  };
  if (x % CHUNK_SIZE < 0) anchor.x --;
  if (z % CHUNK_SIZE < 0) anchor.z --;
  anchor.hash = getChunkHash(anchor.x, anchor.z);
  anchor.biome = getChunkBiome(anchor.x, anchor.z);

  uint8_t is_base_block = block == getTerrainAt(x, y, z, anchor);

  // Look for existing block change entries and replace them
  // 0xFF indicates a missing/restored entry
  for (int i = 0; i < block_changes_count; i ++) {
    if (block_changes[i].block == 0xFF && !is_base_block) {
      block_changes[i].x = x;
      block_changes[i].y = y;
      block_changes[i].z = z;
      block_changes[i].block = block;
      return;
    }
    if (
      block_changes[i].x == x &&
      block_changes[i].y == y &&
      block_changes[i].z == z
    ) {
      if (is_base_block) block_changes[i].block = 0xFF;
      else block_changes[i].block = block;
      return;
    }
  }

  // Don't create a new entry if it contains the base terrain block
  if (is_base_block) return;

  block_changes[block_changes_count].x = x;
  block_changes[block_changes_count].y = y;
  block_changes[block_changes_count].z = z;
  block_changes[block_changes_count].block = block;
  block_changes_count ++;

}

// Returns the result of mining a block, taking into account the block type and tools
// Probability numbers obtained with this formula: N = floor(P * 32 ^ 2)
uint16_t getMiningResult (uint16_t held_item, uint8_t block) {

  switch (block) {

    case B_oak_leaves:
      uint32_t r = fast_rand();
      if (r < 21474836) return I_apple; // 0.5%
      if (r < 85899345) return I_stick; // 2%
      if (r < 214748364) return I_oak_sapling; // 5%
      return 0;
      break;

    case B_stone:
    case B_cobblestone:
    case B_coal_ore:
    case B_iron_ore:
      // Check if player is holding (any) pickaxe
      if (
        held_item != I_wooden_pickaxe &&
        held_item != I_stone_pickaxe &&
        held_item != I_iron_pickaxe &&
        held_item != I_golden_pickaxe &&
        held_item != I_diamond_pickaxe &&
        held_item != I_netherite_pickaxe
      ) return 0;
      break;

    case B_gold_ore:
    case B_redstone_ore:
    case B_diamond_ore:
      // Check if player is holding an iron (or better) pickaxe
      if (
        held_item != I_iron_pickaxe &&
        held_item != I_golden_pickaxe &&
        held_item != I_diamond_pickaxe &&
        held_item != I_netherite_pickaxe
      ) return 0;
      break;

    case B_snow:
      // Check if player is holding (any) shovel
      if (
        held_item != I_wooden_shovel &&
        held_item != I_stone_shovel &&
        held_item != I_iron_shovel &&
        held_item != I_golden_shovel &&
        held_item != I_diamond_shovel &&
        held_item != I_netherite_shovel
      ) return 0;
      break;

    default: break;
  }

  return B_to_I[block];

}

// Rolls a random number to determine whether the player's tool should break
void bumpToolDurability (PlayerData *player) {

  uint16_t held_item = player->inventory_items[player->hotbar];

  // In order to avoid storing durability data, items break randomly with
  // the probability weighted based on vanilla durability.
  uint32_t r = fast_rand();
  if (
    ((held_item == I_wooden_pickaxe || held_item == I_wooden_axe || held_item == I_wooden_shovel) && r < 72796055) ||
    ((held_item == I_stone_pickaxe || held_item == I_stone_axe || held_item == I_stone_shovel) && r < 32786009) ||
    ((held_item == I_iron_pickaxe || held_item == I_iron_axe || held_item == I_iron_shovel) && r < 17179869) ||
    ((held_item == I_golden_pickaxe || held_item == I_golden_axe || held_item == I_golden_shovel) && r < 134217728) ||
    ((held_item == I_diamond_pickaxe || held_item == I_diamond_axe || held_item == I_diamond_shovel) && r < 2751420) ||
    ((held_item == I_netherite_pickaxe || held_item == I_netherite_axe || held_item == I_netherite_shovel) && r < 2114705)
  ) {
    player->inventory_items[player->hotbar] = 0;
    player->inventory_count[player->hotbar] = 0;
    sc_setContainerSlot(player->client_fd, 0, serverSlotToClientSlot(0, player->hotbar), 0, 0);
  }

}

// Checks whether the given block would be mined instantly with the held tool
uint8_t isInstantlyMined (PlayerData *player, uint8_t block) {

  uint16_t held_item = player->inventory_items[player->hotbar];

  if (
    block == B_snow ||
    block == B_snow_block
  ) return (
    held_item == I_stone_shovel ||
    held_item == I_iron_shovel ||
    held_item == I_diamond_shovel ||
    held_item == I_netherite_shovel ||
    held_item == I_golden_shovel
  );

  return (
    block == B_dead_bush ||
    block == B_short_grass ||
    block == B_torch ||
    block == B_lily_pad
  );

}

// Checks whether the given block has to have something beneath it
uint8_t isColumnBlock (uint8_t block) {

  return (
    block == B_snow ||
    block == B_moss_carpet ||
    block == B_cactus ||
    block == B_short_grass ||
    block == B_dead_bush ||
    block == B_sand ||
    block == B_torch
  );

}

uint8_t isPassableBlock (uint8_t block) {

  return (
    block == B_air ||
    block == B_water ||
    block == B_moss_carpet ||
    block == B_short_grass ||
    block == B_dead_bush ||
    block == B_torch
  );

}

void handlePlayerAction (PlayerData *player, int action, short x, short y, short z) {

  // In creative, only the "start mining" action is sent
  // No additional verification is performed, the block is simply removed
  if (action == 0 && GAMEMODE == 1) {
    makeBlockChange(x, y, z, 0);
    return;
  }

  // Ignore actions not pertaining to mining blocks
  if (action != 0 && action != 2) return;

  uint8_t block = getBlockAt(x, y, z);

  // If this is a "start mining" packet, the block must be instamine
  if (action == 0 && !isInstantlyMined(player, block)) return;

  makeBlockChange(x, y, z, 0);

  uint16_t held_item = player->inventory_items[player->hotbar];
  uint16_t item = getMiningResult(held_item, block);
  if (item) givePlayerItem(player, item, 1);
  bumpToolDurability(player);

  // Check if any blocks above this should break
  uint8_t y_offset = 1;
  uint8_t block_above = getBlockAt(x, y + y_offset, z);

  // Iterate upward over all blocks in the column
  while (isColumnBlock(block_above)) {
    // Destroy the next block
    makeBlockChange(x, y + y_offset, z, 0);
    // Check for item drops *without a tool*
    uint16_t item = getMiningResult(0, block_above);
    if (item) givePlayerItem(player, item, 1);
    // Select the next block in the column
    y_offset ++;
    block_above = getBlockAt(x, y + y_offset, z);
  }

}

void spawnMob (uint8_t type, short x, uint8_t y, short z, uint8_t health) {

  for (int i = 0; i < MAX_MOBS; i ++) {
    // Look for type 0 (unallocated)
    if (mob_data[i].type != 0) continue;

    // Assign it the input parameters
    mob_data[i].type = type;
    mob_data[i].x = x;
    mob_data[i].y = y;
    mob_data[i].z = z;
    mob_data[i].data = health & 31;

    // Broadcast entity creation to all players
    for (int j = 0; j < MAX_PLAYERS; j ++) {
      if (player_data[j].client_fd == -1) continue;
      sc_spawnEntity(
        player_data[j].client_fd,
        65536 + i, // Try to avoid conflict with client file descriptors
        recv_buffer, // The UUID doesn't matter, feed it garbage
        type, (double)x + 0.5f, y, (double)z + 0.5f,
        // Face opposite of the player, as if looking at them when spawning
        (player_data[j].yaw + 127) & 255, 0
      );
    }

    break;
  }

}

void hurtEntity (int entity_id, int attacker_id, uint8_t damage_type, uint8_t damage) {

  // Retrieve player data if applicable
  PlayerData *player;
  if (attacker_id < 65536 && attacker_id != -1) {
    if (getPlayerData(attacker_id, &player)) return;
  } else if (entity_id < 65536) {
    if (getPlayerData(entity_id, &player)) return;
  }

  if (attacker_id < 65536 && attacker_id != -1) { // Attacker is a player
    // Check if attack cooldown flag is set
    if (player->flags & 0x01) return;
    // Scale damage based on held item
    uint16_t held_item = player->inventory_items[player->hotbar];
    if (held_item == I_wooden_sword) damage *= 4;
    else if (held_item == I_golden_sword) damage *= 4;
    else if (held_item == I_stone_sword) damage *= 5;
    else if (held_item == I_iron_sword) damage *= 6;
    else if (held_item == I_diamond_sword) damage *= 7;
    else if (held_item == I_netherite_sword) damage *= 8;
    // Enable attack cooldown
    player->flags |= 0x01;
  }

  // Whether this attack caused the target entity to die
  uint8_t entity_died = false;

  if (entity_id < 65536) { // The attacked entity is a player
    if (player->health <= damage) {
      player->health = 0;
      entity_died = true;
    } else player->health -= damage;
    // Update health on the client
    sc_setHealth(player->client_fd, player->health, player->hunger);
  } else { // The attacked entity is a mob
    MobData *mob = &mob_data[entity_id - 65536];
    uint8_t mob_health = mob->data & 31;
    if (mob_health <= damage) {
      mob->data -= mob_health;
      entity_died = true;
    } else mob->data -= damage;
  }

  // Broadcast damage event to all players
  for (int i = 0; i < MAX_PLAYERS; i ++) {
    int client_fd = player_data[i].client_fd;
    if (client_fd == -1) continue;
    sc_damageEvent(client_fd, entity_id, damage_type);
    if (entity_died) sc_entityEvent(client_fd, entity_id, 3);
  }

}

// Simulates events scheduled for regular intervals
// Takes the time since the last tick in microseconds as the only arguemnt
void handleServerTick (int64_t time_since_last_tick) {

  // Send Keep Alive and Update Time packets to all in-game clients
  world_time = (world_time + time_since_last_tick / 50000) % 24000;
  for (int i = 0; i < MAX_PLAYERS; i ++) {
    if (player_data[i].client_fd == -1) continue;
    sc_keepAlive(player_data[i].client_fd);
    sc_updateTime(player_data[i].client_fd, world_time);
    // Reset attack cooldown if at least a second has passed
    if (time_since_last_tick >= 1000000) {
      player_data[i].flags &= ~0x01;
    }
  }

  /**
   * If the RNG seed ever hits 0, it'll never generate anything
   * else. This is because the fast_rand function uses a simple
   * XORshift. This isn't a common concern, so we only check for
   * this periodically. If it does become zero, we reset it to
   * the world seed as a good-enough fallback.
   */
  if (rng_seed == 0) rng_seed = world_seed;

  // Tick mob behavior
  for (int i = 0; i < MAX_MOBS; i ++) {
    if (mob_data[i].type == 0) continue;

    // Mob has died, deallocate it
    if ((mob_data[i].data & 31) == 0) {
      mob_data[i].type = 0;
      for (int j = 0; j < MAX_PLAYERS; j ++) {
        if (player_data[j].client_fd == -1) continue;
        // Spawn death smoke particles
        sc_entityEvent(player_data[j].client_fd, 65536 + i, 60);
        // Remove the entity from the client
        sc_removeEntity(player_data[j].client_fd, 65536 + i);
      }
      continue;
    }

    uint8_t passive = (
      mob_data[i].type == 25 || // Chicken
      mob_data[i].type == 28 || // Cow
      mob_data[i].type == 95 || // Pig
      mob_data[i].type == 106 // Sheep
    );

    uint32_t r = fast_rand();

    // Skip 25% of passive mob ticks randomly
    if (passive && (r & 3)) continue;

    // Find the player closest to this mob
    PlayerData* closest_player;
    uint32_t closest_dist = 65536;
    for (int j = 0; j < MAX_PLAYERS; j ++) {
      if (player_data[j].client_fd == -1) continue;
      uint16_t curr_dist = (
        abs(mob_data[i].x - player_data[j].x) +
        abs(mob_data[i].z - player_data[j].z)
      );
      if (curr_dist < closest_dist) {
        closest_dist = curr_dist;
        closest_player = &player_data[j];
      }
    }

    // Despawn mobs past a certain distance from nearest player
    if (closest_dist > MOB_DESPAWN_DISTANCE) {
      mob_data[i].type = 0;
      continue;
    }

    short new_x = mob_data[i].x, new_z = mob_data[i].z;
    uint8_t new_y = mob_data[i].y, yaw = 0;

    if (passive) { // Passive mob movement handling

      // Move by one block on the X or Z axis
      // Yaw is set to face in the direction of motion
      if ((r >> 2) & 1) {
        if ((r >> 1) & 1) { new_x += 1; yaw = 192; }
        else { new_x -= 1; yaw = 64; }
      } else {
        if ((r >> 1) & 1) { new_z += 1; yaw = 0; }
        else { new_z -= 1; yaw = 128; }
      }
      // Vary the yaw angle to look just a little less robotic
      yaw += ((r >> 7) & 31) - 16;

    } else { // Hostile mob movement handling

      // If we're already next to the player, hurt them and skip movement
      if (closest_dist < 3 && abs(mob_data[i].y - closest_player->y) < 2) {
        hurtEntity(closest_player->client_fd, 65536 + i, D_generic, 6);
        continue;
      }

      // Move towards the closest player on 8 axis
      // The condition nesting ensures a correct yaw at 45 degree turns
      if (closest_player->x < mob_data[i].x) {
        new_x -= 1; yaw = 64;
        if (closest_player->z < mob_data[i].z) { new_z -= 1; yaw += 32; }
        else if (closest_player->z > mob_data[i].z) { new_z += 1; yaw -= 32; }
      }
      else if (closest_player->x > mob_data[i].x) {
        new_x += 1; yaw = 192;
        if (closest_player->z < mob_data[i].z) { new_z -= 1; yaw -= 32; }
        else if (closest_player->z > mob_data[i].z) { new_z += 1; yaw += 32; }
      } else {
        if (closest_player->z < mob_data[i].z) { new_z -= 1; yaw = 128; }
        else if (closest_player->z > mob_data[i].z) { new_z += 1; yaw = 0; }
      }

    }

    // Check if the blocks we're moving into are passable:
    //   if yes, and the block below is solid, keep the same Y level;
    //   if yes, but the block below isn't solid, drop down one block;
    //   if not, go up by up to one block;
    //   if going up isn't possible, skip this iteration.
    uint8_t block = getBlockAt(new_x, new_y, new_z);
    uint8_t block_above = getBlockAt(new_x, new_y + 1, new_z);
    if (!isPassableBlock(block) || !isPassableBlock(block_above)) {
      block = block_above;
      block_above = getBlockAt(new_x, new_y + 2, new_z);
      if (isPassableBlock(block) && isPassableBlock(block_above)) new_y += 1;
      else continue;
    } else {
      uint8_t block_below = getBlockAt(new_x, new_y - 1, new_z);
      if (isPassableBlock(block_below)) new_y -= 1;
    }

    // Store new mob position
    mob_data[i].x = new_x;
    mob_data[i].y = new_y;
    mob_data[i].z = new_z;

    // Broadcast relevant entity movement packets
    for (int j = 0; j < MAX_PLAYERS; j ++) {
      if (player_data[j].client_fd == -1) continue;
      int entity_id = 65536 + i;
      sc_teleportEntity (
        player_data[j].client_fd, entity_id,
        (double)new_x + 0.5, new_y, (double)new_z + 0.5,
        yaw * 360 / 256, 0
      );
      sc_setHeadRotation(player_data[j].client_fd, entity_id, yaw);
    }

  }

}