Per-Player Blocks

Send ServerSetBlock packets directly to a player’s packet handler to show fake blocks without modifying the world.

Sending Packets to Players

Use PlayerRef.getPacketHandler().write() to send packets to specific players:

PlayerRef player = ...; // get from event or command
Packet packet = ...;    // the packet to send

player.getPacketHandler().write(packet);

ServerSetBlock Packet

Sets a single block for the receiving player. Packet ID: 140

Structure

Field	Type	Description
x	int (4 bytes LE)	World X coordinate
y	int (4 bytes LE)	World Y coordinate
z	int (4 bytes LE)	World Z coordinate
blockId	int (4 bytes LE)	Block type index from asset map
filler	short (2 bytes LE)	For multi-block structures, use 0 for simple blocks
rotation	byte	Rotation index 0-23

Getting Block IDs

Block IDs are runtime indices from the block type asset map:

import com.hypixel.hytale.server.world.block.BlockType;

// get block ID by name
int stoneId = BlockType.getAssetMap().getIndex("Stone");
int airId = BlockType.getAssetMap().getIndex("Air");
int glassId = BlockType.getAssetMap().getIndex("Glass");

Example: Send Fake Block

import com.hypixel.hytale.server.world.block.BlockType;
import com.hypixel.hytale.server.core.network.packet.server.ServerSetBlock;

public void sendFakeBlock(PlayerRef player, int x, int y, int z, String blockName) {
    int blockId = BlockType.getAssetMap().getIndex(blockName);

    ServerSetBlock packet = new ServerSetBlock(
        x, y, z,           // position
        blockId,           // block type
        (short) 0,         // filler (0 for simple blocks)
        (byte) 0           // no rotation
    );

    player.getPacketHandler().write(packet);
}

// usage
sendFakeBlock(player, 100, 64, 200, "Diamond");

ServerSetBlocks Packet

Sets multiple blocks in one packet. More efficient for bulk changes. Packet ID: 141

import com.hypixel.hytale.server.core.network.packet.server.ServerSetBlocks;

public void sendFakeBlocks(PlayerRef player, List<BlockChange> changes) {
    ServerSetBlocks packet = new ServerSetBlocks(changes);
    player.getPacketHandler().write(packet);
}

Practical Examples

Fake Wall (Barrier)

Show a temporary barrier only to one player:

public void showBarrier(PlayerRef player, int x, int y, int z, int width, int height) {
    int barrierBlock = BlockType.getAssetMap().getIndex("Barrier");

    for (int dx = 0; dx < width; dx++) {
        for (int dy = 0; dy < height; dy++) {
            ServerSetBlock packet = new ServerSetBlock(
                x + dx, y + dy, z,
                barrierBlock, (short) 0, (byte) 0
            );
            player.getPacketHandler().write(packet);
        }
    }
}

Resetting to Real Blocks

To “remove” fake blocks, send the actual world block data:

public void resetBlock(PlayerRef player, World world, int x, int y, int z) {
    BlockState realBlock = world.getBlockState(x, y, z);
    int blockId = BlockType.getAssetMap().getIndex(realBlock.getType().getIdentifier());

    ServerSetBlock packet = new ServerSetBlock(
        x, y, z,
        blockId,
        (short) 0,
        realBlock.getRotation()
    );

    player.getPacketHandler().write(packet);
}

Limitations

• Chunk reloads: When a player reloads chunks (moving far away and back), fake blocks are lost
• Block updates: Real block changes in the same position will overwrite fake blocks
• Interactions: Players cannot interact with fake blocks (they’re client-side only)
• Performance: Sending many individual packets can be slow; use ServerSetBlocks for bulk changes