Getting your roblox portal gun script physics to actually feel right is honestly one of the hardest things you can do in Studio. We've all been there: you spend hours coding a basic teleportation script, you step through the blue portal, and instead of flying out the orange one with cool momentum, your character just kind of blips into existence and stops dead. It's frustrating because the whole magic of a portal gun isn't just the teleportation; it's the way it preserves energy and messes with gravity.
If you're trying to build a puzzle game or just a tech demo, you can't just rely on a simple HumanoidRootPart.CFrame swap. You have to account for the math behind the movement. Let's break down what actually goes into making these scripts feel like the real deal without making your brain explode from the vector math.
The struggle with momentum and velocity
The biggest hurdle with roblox portal gun script physics is the conservation of momentum. In the original Portal games, the rule was "speedy thing goes in, speedy thing comes out." In Roblox, the physics engine doesn't automatically know that you want to transfer the velocity from one orientation to another.
When a player hits a portal on the floor while falling, they have a lot of downward velocity. If the exit portal is on a wall, that downward velocity needs to be converted into forward velocity. If you don't script this manually, the game engine just sees a part (the player) suddenly changing position. It doesn't inherently understand that the direction of travel needs to rotate based on the exit portal's "normal" vector.
To fix this, you usually have to grab the player's AssemblyLinearVelocity right before they touch the portal. Then, you use some CFrame math to rotate 그 velocity vector so it aligns with the direction the exit portal is facing. It sounds complicated, but it's basically just telling the engine, "Hey, take all that speed and point it that way instead."
Why Raycasting is your best friend
Before you even worry about the physics of the player, you have to worry about the physics of the portal itself. You can't just spawn a portal anywhere. You need to know where the "bullet" hits, what direction the wall is facing, and if there's even enough room for a portal to fit.
This is where Raycasting comes in. When the player clicks, your script fires a ray. If that ray hits a part, you get a RaycastResult. This result gives you the exact position and, more importantly, the Normal. The normal is basically a vector pointing straight out from the surface. If you shoot a flat floor, the normal points up. If you shoot a wall, it points away from the wall.
Your roblox portal gun script physics depends on this normal to orient the portal part correctly. If your math is off, the portal might be embedded in the wall or floating a few inches away, which breaks the illusion immediately. You also have to check if the surface is too small. There's nothing worse than a portal hanging off the edge of a thin pillar—it just looks broken.
Dealing with the "Clipping" nightmare
One thing nobody tells you about making a portal script is how much the player's collision box hates you. Roblox characters are essentially tall rectangles. When you teleport a player through a portal, there's a split second where half the body is in the entrance and the other half is at the exit.
If you just move the character, they often get stuck in the wall or "glitch" back to the entrance because the physics engine detects a collision with the wall the portal is sitting on. To get around this, a lot of high-end scripts actually disable collisions between the player and the wall briefly, or they use a clever trick with CollisionGroups.
Another way to handle this is to offset the teleportation exit point slightly. You don't want to spawn the player inside the wall; you want to spawn them just an inch or two in front of the exit portal. It's a tiny detail, but it makes the transition feel a lot smoother and prevents that annoying "stuck in the geometry" bug that ruins the flow of gameplay.
The visual side of physics
While we're talking about roblox portal gun script physics, we have to mention the visuals. If the portal looks like a flat sticker, it doesn't feel like a physical hole in space. Now, making "real" seamless portals in Roblox is notoriously difficult because we don't have easy access to stencil buffers or advanced render targets.
Most creators use ViewportFrames to create a "camera" view of what's on the other side. But here's the kicker: the physics of the camera needs to match the physics of the player. If you move your head, the view inside the portal needs to shift proportionally. If the perspective doesn't match, the player's brain will realize it's an illusion, and the sense of physical space is lost. It's all about creating that "depth" so it feels like you're actually looking through a hole.
Handling the server-client lag
Physics in Roblox is a tug-of-war between the server and the client. If you handle the portal teleportation entirely on the server, there will be a noticeable delay. You'll hit the portal, wait 100 milliseconds, and then pop out the other side. It feels laggy and unresponsive.
To make the roblox portal gun script physics feel snappy, you usually have to handle the actual movement on the client side first. This is called "client-side prediction." The client moves the player instantly, and then the server verifies it. However, you have to be careful. If the server and client disagree on where the player should be, the player will get "rubber-banded" back to the entrance.
The sweet spot is usually letting the client handle the camera and the initial CFrame jump, while the server handles the actual "state" of the portals (where they are and who can use them). It's a balancing act that takes a lot of testing to get right.
Why CFrame math is better than BodyMovers
In the old days of Roblox, we used BodyVelocity or BodyForce to move things. These days, most people go for direct CFrame manipulation or the newer LinearVelocity objects. For a portal gun, direct CFrame changes are usually the way to go for the initial "teleport," but you want to let the physics engine take back control the moment the player exits.
If you try to manually "slide" the player through the portal using code, it usually looks jittery. The best approach is: 1. Detect the touch. 2. Instantly set the CFrame of the player to the exit portal's location + an offset. 3. Rotate the player's AssemblyLinearVelocity to match the new direction. 4. Let the Roblox physics engine handle the rest of the arc.
This way, the player still feels the "weight" of their character. If they were falling, they'll keep that sense of falling, just in a different direction.
Final thoughts on the portal logic
Building a solid roblox portal gun script physics system is basically a rite of passage for Roblox scripters. It forces you to learn about Raycasting, CFrame math, vector rotation, and how to cheat the physics engine into doing what you want.
It's never going to be perfect on the first try. You'll probably spend a few days flying out of portals at Mach 5 or getting launched into the void because a vector was inverted. But once you get that first smooth transition where you jump into a floor and fly out of a wall, it's incredibly satisfying. Just remember to keep your math clean, use Raycasts for everything, and don't forget to account for that pesky momentum!