Try it first: free playable Windows demo, no Unreal Engine needed. Grab, carry and throw crates next to a bot at 150 ms of ping with GrabNet, then the same with the usual tutorial approach, and feel the difference: https://drive.google.com/file/d/1byuO7qJLIpEIQDjpR3v1Z5AbufBtDI-W/view

GrabNet lets players grab, carry, share, throw and shove physics objects in multiplayer without the round-trip delay in their hands and without objects jumping on everyone else's screen. Add a component to your physics actors, another to your character, and call Try Grab / Release / Throw.

The usual way (an RPC to the server, a physics handle on the server, the engine's physics replication back) makes the object trail your hand by a full round trip and jump when you throw it. GrabNet hands the simulation to whoever holds the object, replays their motion smoothly for everyone else, and gives it back to the server once a throw comes to rest.

Measured in the included demo project

Dedicated server, two bot clients with 150 ms of added latency, the same routine (grab a crate, carry it while sweeping the view, throw it), 12 rounds each:

• Object behind the holder's hand: 118 cm on average the tutorial way, 15 cm with GrabNet.

• Visible jumps in the holder's hands: 298 vs 0.

• Visible jumps watching the other player's crate: 200 vs 25.

• With 3% packet loss and 30 ms jitter: 120 cm vs 15 cm behind the hand; 428 vs 0 jumps in the holder's hands; 301 vs 2 watching the other player.

• Two GrabNet players lifting a 90 kg sofa to chest height and carrying it 12 m together, again and again: 0 jumps and 0 snaps on both clients.

What you get

• GrabNet Object component: authority handoff to the holder, smooth corrections and ballistic extrapolation for free objects, replay of the holder's motion for observers, validated state relay, sleep matching so everyone ends with the object in the same place, teleports for respawns.

• GrabNet Hand component: predicted grab with server confirmation, hold at the grabbed distance with optional orientation lock to the view, throw with mass scaling and inherited velocity, predicted shove, break when pulled away.

• Carrying together: several hands on one object, each holding its own point; Holders To Lift (two players needed for a sofa, one can only drag it).

• Thrown objects stay simulated by the thrower until they land, so throws never correct.

• Server validation: hold distance, speeds, throw speed, interaction distance; authority taken back from clients that go out of bounds. Allow Holder Authority off keeps the server simulating at all times.

• Blueprint events (On Grabbed, On Released, On Thrown, On Authority Changed), queries and stats.

• Debug drawing (grabnet.Debug 1) and verbose correction logs.

• Demo project: side-by-side comparison with the tutorial way, shared sofa test, bots, network emulation and the measurement tools.

Requirements and limits

• Unreal Engine 5.6, 5.7 and 5.8. Dedicated and listen servers. Blueprint or C++.

• Single rigid bodies (the actor's root primitive). Ragdolls, ropes and vehicles are not part of 1.0.

• On a listen server, the host sees a small correction when a client hands an object back.

Documentation and support

The included README covers setup, carrying together, throwing, events, security, debugging and every setting. Support: [email protected].