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Next-gen zero-allocation packet framework for Paper 1.21+. High-performance Kotlin alternative to ProtocolLib.

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Release
1.1.0

ClCody released Slipstream version 1.1.0 on June 3, 2026

πŸš€ What's New in 1.1.0

This release brings massive improvements to the built-in physics engine, introduces a zero-overhead packet factory, and expands the API with a wide range of zero-allocation wrappers.

🧬 Physics & Backtrack Engine Upgrades

The ClientStateTracker and PlayerState have been significantly deepened to provide a flawless backtrack and simulation experience:

  • Dynamic Hitboxes (AABB): MutableAABB now dynamically adjusts its dimensions based on the player's state. It accurately simulates heights and widths for Sneaking (1.5h), Swimming/Crawling/Elytra (0.6h), Sitting, and Trident Spin Attacks.
  • Attribute Support: The tracker now reads the GENERIC_SCALE attribute directly from the player to perfectly scale bounding boxes.
  • Ping-less Simulation (Transaction IDs): Added interception of ServerboundPongPacket. The Ring Buffer now binds exact transactionIds to each TrackedFrame. This allows you to simulate backtrack based on explicit transaction confirmations rather than unpredictable network ping!

🏭 SlipstreamFactory (0-Overhead Packet Creation)

Tired of ProtocolLib's heavy new PacketContainer(type) reflection?

  • Introduced SlipstreamFactory which utilizes sun.misc.Unsafe and constant-folded MethodHandles to instantly instantiate NMS packets without calling their constructors. This means you can create and spam fake packets with absolute zero overhead.
  • New Player Extensions: Added player.sendPacket(wrapper.handle) to send packets down the pipeline (triggering your onPacketOut listeners) and player.receiveFakePacket(wrapper.handle) to simulate incoming client packets.

πŸ“¦ Extensive Zero-Allocation Wrappers

We expanded our @JvmInline value class wrapper coverage so you rarely have to use raw modifier() indexes. New wrappers include:

  • WrapperPlayerCommandPacket (Sprint, Sneak, Elytra states)
  • WrapperPlayerInputPacket (WASD, Jump, Shift)
  • WrapperPongPacket (Transaction IDs)
  • WrapperChatPacket & WrapperSystemChatPacket
  • WrapperPlayerInfoUpdatePacket (TabList & Profiles)
  • WrapperUpdateAttributesPacket & WrapperSetEntityDataPacket

πŸ›  Fixes & Chores

  • Migrated ClientStateTracker to use the new inline wrappers instead of raw modifier reads.
  • Fixed internal registry bootstrapping (Bootstrap.bootStrap()) for offline test environments.
  • Expanded test coverage for MutableAABB, PlayerState, and the new SlipstreamFactory.

Full Changelog: https://github.com/ClCody/Slipstream/compare/v1.0.0...v1.1.0

Information

Published onJune 3, 2026
Downloads0

Platforms

Paper Paper (1.21-1.21.11)