zelthrSeeYou

A server-side Anti-ESP plugin for Paper servers that prevents players from using X-ray, ESP hacks, or texture pack exploits to see ores, containers, and other protected blocks through walls.

Built for the Zelthr server ecosystem.

Source: github.com/ZeWinny/zelthrSeeYou

---

How It Works

zelthrSeeYou uses a chunk-level block substitution approach:

1. For each online player, the plugin scans protected blocks within a configurable chunk radius.
2. For each block, it performs a line-of-sight raycast (rayTraceBlocks) from the player's eye position.
3. Blocks that are not directly visible are replaced with fake block data sent via sendMultiBlockChange() — the actual world is never modified.
4. When the player gains line-of-sight, the real block data is restored transparently.
5. When a new chunk is sent to the player, protected blocks in that chunk are immediately hidden via packet interception.

---

Features

• Server-side only — no client mod required
• Chunk-based line-of-sight detection using rayTraceBlocks
• Fake block packet injection — the world is never modified
• Configurable protected block list (ores, containers, spawners, etc.)
• Per-world enable/disable
• Fake material substitution per environment (Overworld above/below y=0, Nether, End)
• Automatic variant expansion — listing CHEST covers all chest types; SHULKER_BOX covers all colors; copper blocks cover all weathering stages
• Supports both ProtocolLib and PacketEvents — uses whichever is available, disables itself if neither is found
• Block updates (place/break) trigger immediate re-evaluation for nearby players

---

Requirements

Dependency	Version
Paper API	26.1.2
Java	25
ProtocolLib or PacketEvents	ProtocolLib 5.4.0 / PacketEvents 2.12.1

At least one of ProtocolLib or PacketEvents must be installed. The plugin will disable itself on startup if neither is found.

---

Installation

1. Build the plugin jar (see Building) or download a release.
2. Place the jar in your server's plugins/ folder.
3. Ensure ProtocolLib or PacketEvents is also installed.
4. Start the server — config.yml will be generated automatically.

---

Building

git clone https://github.com/ZeWinny/zelthrSeeYou.git
cd zelthrSeeYou
./gradlew build

Output jar will be in build/libs/. Requires Java 25. Uses paperweight-userdev for NMS access.

---

Configuration

# Enable or disable the plugin globally
enabled: true

# Worlds where Anti-ESP is active
enabled-worlds:
  - world
  - world_nether
  - world_the_end

# Blocks that will be hidden when not in line-of-sight
protected-blocks:
  - CHEST
  - TRAPPED_CHEST
  - BARREL
  - ENDER_CHEST
  - SHULKER_BOX
  - SPAWNER
  - TRIAL_SPAWNER
  - VAULT
  - COAL_ORE
  - DEEPSLATE_COAL_ORE
  - COPPER_ORE
  - DEEPSLATE_COPPER_ORE
  - DIAMOND_ORE
  - DEEPSLATE_DIAMOND_ORE
  - ANCIENT_DEBRIS
  - GOLD_ORE
  - DEEPSLATE_GOLD_ORE
  - IRON_ORE
  - DEEPSLATE_IRON_ORE
  - REDSTONE_ORE
  - DEEPSLATE_REDSTONE_ORE
  - LAPIS_ORE
  - DEEPSLATE_LAPIS_ORE
  - EMERALD_ORE
  - DEEPSLATE_EMERALD_ORE
  - NETHER_GOLD_ORE
  - NETHER_QUARTZ_ORE
  - GILDED_BLACKSTONE

# Radius in chunks around the player where blocks are always evaluated
reveal-chunk-radius: 3

# How often in ticks to recalculate line-of-sight per player (minimum: 1)
update-interval-ticks: 4

# Maximum block changes sent to a player per update cycle (minimum: 16)
max-changes-per-update: 256

# What material to substitute for hidden blocks, per environment
fake-materials:
  overworld-above-zero: STONE
  overworld-below-zero: DEEPSLATE
  nether: NETHERRACK
  end: END_STONE

---

Performance

rayTraceBlocks is CPU-intensive and runs every update-interval-ticks ticks for every online player. Tuning update-interval-ticks (default: 4) is the most effective way to reduce overhead. max-changes-per-update caps how many block changes are sent per cycle if a player has many blocks entering or leaving line-of-sight at once.

See a real-world spark profiler report for a performance sample.

---

License

MIT