Trying to figure out a solid roblox gravity gun script physics setup is basically a rite of passage for any developer on the platform. If you've ever played Half-Life 2, you know exactly why everyone wants one. There is something deeply satisfying about pointing a tool at a random crate, watching it hover in mid-air, and then launching it across the map at a high-speed velocity. But, as anyone who's actually tried to script this knows, making it feel "right" instead of "glitchy" is where the real work happens.
In Roblox, you aren't just moving a part from point A to point B. You're interacting with a complex physics engine that's trying to calculate mass, friction, and velocity all at once. If your script is even slightly off, that crate you're holding is going to start vibrating violently or, worse, launch you into the stratosphere because of a collision glitch.
How the Physics Actually Work
When we talk about a roblox gravity gun script physics system, we're really talking about two main things: finding the object and then controlling its position. The "finding" part is usually done through raycasting. You fire an invisible line from the player's camera or the gun's tip, and if it hits a part that isn't anchored, that's your target.
The "controlling" part is where it gets spicy. Back in the day, everyone used BodyPosition and BodyGyro. These are now technically "legacy" objects, meaning Roblox wants us to stop using them in favor of newer constraints like AlignPosition and AlignOrientation. The old stuff still works, but the new constraints are way more stable and give you a lot more control over how "snappy" or "floaty" the object feels.
Setting Up the Hold Mechanism
Once you've grabbed an object with your raycast, you need to keep it at a fixed distance in front of the player. If you just set the part's position every frame using a RunService.RenderStepped loop, the physics engine will hate you. The object won't have any actual momentum, and it'll just teleport through walls.
Instead, you want to use forces. By using an AlignPosition constraint, you're telling the engine: "Hey, try your best to move this part to this specific coordinate." This allows the part to still interact with the world. If you walk into a wall while holding a box, the box will actually bump against the wall instead of clipping through it and causing a physics explosion.
I've found that setting the Responsiveness of these constraints is the secret to making it feel good. If it's too high, the object feels like it's glued to your hand—too low, and it feels like you're pulling it with a rubber band. You want that sweet spot where there's just a tiny bit of weight to it.
The Nightmare of Network Ownership
If you've been building on Roblox for a while, you know the pain of "laggy physics." This usually happens because of network ownership. Basically, the server and the client are fighting over who gets to calculate where that object is.
When a player picks up an object with your roblox gravity gun script physics tool, you must set the network ownership of that part to the player. If you don't, there will be a weird delay between the player moving and the object following. It'll look stuttery and gross.
By calling part:SetNetworkOwner(player), the player's computer takes over the calculations. Everything becomes buttery smooth. Just remember to set the owner back to nil (the server) once they drop the object, or else that part might just disappear or stop moving for everyone else in the game.
Adding the "Gun" to the Gravity Gun
Grabbing things is cool, but throwing things is better. To handle the "launch" mechanic, you're basically just applying a massive amount of AssemblyLinearVelocity to the part the moment it's released.
You can calculate the direction by taking the player's camera look-vector and multiplying it by a "throw power" variable. But here is a pro tip: don't just launch it from the center of the part. If you want it to look realistic, you can add a bit of angular velocity (spin) so the object tumbles through the air. It makes the roblox gravity gun script physics feel much more natural and less like you're just firing a laser beam.
Dealing With Mass and Size
One problem you'll run into is that a tiny pebble and a massive skyscraper-sized brick will behave exactly the same if you aren't careful. Roblox physics calculates force based on mass. If your gravity gun has a constant force, it might pick up a small chair just fine but completely fail to lift a heavy boulder.
You can script a "mass compensator" that checks the AssemblyMass of the object and scales the power of your AlignPosition accordingly. That way, the gun feels consistent regardless of what you're picking up. Or, if you want to be more realistic, you can cap the mass so players can't just pick up the entire map and toss it into the ocean. (Though, let's be honest, that's usually the most fun part of any physics sandbox).
Common Pitfalls to Avoid
I can't tell you how many times I've seen a roblox gravity gun script physics setup fail because the developer forgot about "Player-Part" collisions. If the object you are holding hits your own character's hitbox, it can create a feedback loop where the object pushes you, which moves the object, which pushes you harder, and suddenly you're flying across the map at light speed.
The easiest way to fix this is using Collision Groups. You can put the player in one group and the "held object" in another, then tell the physics engine to ignore collisions between those two groups. It saves so much frustration and prevents those random "physics flings" that plague so many Roblox games.
Making it Look Good
A script is nothing without some visual flair. If you want your gravity gun to actually look like a gravity gun, you should add a Beam or a Lightning effect between the tip of the gun and the object. You can update the beam's endpoints every frame.
Add some sound effects, too—maybe a low hum while holding an object and a satisfying "thwomp" sound when you launch it. These small details distract from any minor physics hiccups and make the whole experience feel way more polished.
Why Physics-Based Gameplay is Worth It
It might seem like a lot of work just to move some blocks around, but getting your roblox gravity gun script physics right opens up a whole world of gameplay possibilities. You can make puzzles where players have to stack boxes to reach a ledge, or combat games where the environment itself is the weapon.
The Roblox engine is surprisingly powerful when you stop fighting against it and start working with its constraints. It's all about trial and error. You'll probably break the game a few dozen times, see parts fly into the void, and wonder why your character just did a 360-degree flip for no reason. But once it clicks, and you're standing there effortlessly juggling physics objects, it's all worth it.
So, if you're stuck on your script, just remember: check your network ownership, use modern constraints, and for the love of everything, use collision groups. Happy scripting!