Curveball Control: Mastering Zipline Tangents

So you’ve dropped a zipline. It goes from Point A to Point B. It’s functional. It’s boring. It looks like a straight line drawn by someone who hates joy.

If you want your island to feel like a high-speed parkour course or a chaotic battle royale drop zone, you need curves. You need swoops. You need that heart-in-your-throat moment when the zipline dips before shooting back up.

The secret weapon isn’t magic—it’s Tangent Intensity.

In this tutorial, we’re going to stop building straight lines and start building experiences. We’ll learn how to control the "shape" of your zipline using the Scene Graph’s hierarchy, turning a simple ride into a rollercoaster. No coding required to start, but you’ll learn the logic that powers it.

What You'll Learn

• Scene Graph Hierarchy: How devices "talk" to each other through parent-child relationships (like a squad leader calling shots).
• Tangent Vectors: Understanding direction and influence in 3D space.
• Tangent Intensity: The slider that turns a straight line into a curve.
• Debugging with Visuals: Using the editor’s snap tools to see what your code (and your devices) are actually doing.

How It Works

The Scene Graph: Your Island’s Family Tree

Imagine your Fortnite island is a giant family tree. This is called the Scene Graph.

In the Scene Graph, every object (a prop, a zipline, a player) is a Node. Nodes can have Parents and Children.

• Parent: The boss. If the boss moves, the minion moves with them.
• Child: The follower. It inherits the parent’s position and rotation.

Think of a Zipline Control Point like a flag on a rope.

• The Start Point is Flag A.
• The End Point is Flag B.
• The Rope connects them.

By default, the rope is straight. But what if Flag A is twisted sideways? Does the rope twist? No. The rope ignores the twist. It just goes straight to Flag B.

This is where Tangent Intensity comes in.

Tangent Intensity: The "Grip Strength"

A Tangent is a mathematical fancy word for "the direction this object is facing right now."

When you place a Zipline Control Point, it has a forward direction (the little green arrow you see in the editor).

• Tangent Intensity is a number (usually between 0 and 1000, default 1000).
• It controls how hard the zipline curve "grips" the forward direction of the Control Point.

The Game Mechanic Analogy: Think of Tangent Intensity like the Grip Strength of a player holding a controller.

• Intensity 0: The player has no grip. They let go. The rope goes straight. No curve.
• Intensity 1000: The player is white-knuckling the controller. The rope must curve in the direction the flag is pointing.

If you want a zipline to swoop down before shooting up, you don’t move the End Point. You rotate the Start Point so it’s facing down, and you crank the Intensity up. The zipline listens to the flag’s direction, not just its location.

Why Not Just Move the Points?

You could build a curve using only Start and End points by adding dozens of intermediate control points. But that’s messy. It’s like trying to draw a perfect circle by placing 50 dots.

Using Tangent Intensity is like having a pen tool. You set the direction, and the software draws the smooth curve between them. It’s cleaner, faster, and gives you precise control over the "feel" of the ride.

Let's Build It

We’re going to build a "Drop-and-Loop" Zipline.

The Goal: A zipline that starts high, dives sharply downward (like a rollercoaster drop), and then levels out.

Step 1: The Setup (The Scene Graph)

1. Open UEFN and create a new island (or use an existing one).
2. Place a Zipline Start Point prop.
3. Place a Zipline End Point prop.
4. Connect them with a Zipline device (or let the points auto-generate the line if your version supports it).

Note: In many UEFN versions, placing the Start and End points automatically creates the zipline path. If not, use the Zipline device and assign the points.

Step 2: The Problem (Boring Straight Line)

Right now, your zipline is a straight line from A to B. It’s safe. It’s boring. Let’s make it dangerous.

Step 3: The Fix (Tangent Intensity)

1. Select the Zipline Start Point.
2. Look at the Details Panel on the right.
3. Find the Tangent Intensity option.
4. Change the value from 1000.0 to 0.0.

Watch what happens. The zipline snaps to a perfectly straight line between the two points. The Start Point’s rotation (the green arrow) is now ignored. The "grip" is gone.

5. Now, set Tangent Intensity back to 1000.0.
6. Rotate the Zipline Start Point so its green arrow points straight down (towards the ground).

Watch what happens. The zipline now curves downward from the start point before curving back up to the End Point. It creates a "dip."

Step 4: Fine-Tuning (The "Feel")

• Too sharp? Lower the Tangent Intensity (e.g., 500.0). The curve will be gentler.
• Too flat? Increase it (e.g., 2000.0 if allowed, or keep at 1000 and rotate the flag more aggressively).
• Want a loop? Rotate the Start Point forward, and the End Point backward. The zipline will arc up and then down.

The Verse Logic (Behind the Scenes)

You don’t need to write code to use Tangent Intensity—it’s an Editable Property on the device. But understanding the logic helps you debug.

In Verse, this logic is handled by the Zipline component’s internal solver. It takes:

1. Position A (Start Point Location)
2. Tangent A (Start Point Forward Direction)
3. Intensity A (Tangent Intensity Value)
4. Position B (End Point Location)
5. Tangent B (End Point Forward Direction)
6. Intensity B (Tangent Intensity Value)

And it calculates a Cubic Bezier Curve (a type of smooth mathematical curve). The Intensity values act as the "handle length" for the Bezier curve. Longer handles = more dramatic curves.

Try It Yourself

Challenge: The "Swoop and Hop"

Build a zipline that:

1. Starts high on a mountain.
2. Dives sharply down (like a skydive).
3. Levels out at the bottom.
4. Ends at a platform 50 meters away.

Hint:

• Don’t just move the End Point.
• Rotate the Start Point to face down.
• Rotate the End Point to face forward (horizontal).
• Adjust the Tangent Intensity on both ends until the curve feels smooth, not jagged.

Bonus: Add a Prop Mover at the end that launches the player into the air when they land. Now you have a full combo: Dive -> Land -> Launch.

Recap

• Scene Graph Hierarchy is how devices relate to each other. Parents move, children follow.
• Tangent is the direction an object is facing.
• Tangent Intensity controls how much the zipline curve "listens" to that direction.
• 0 Intensity = Straight line (ignores rotation).
• 1000 Intensity = Maximum curve influence (follows rotation).

Stop building straight lines. Start building experiences. Your players will thank you (or at least, they won’t fall asleep waiting for the next match).

References

• https://dev.epicgames.com/documentation/en-us/fortnite-creative/using-zipline-devices-in-fortnite-creative
• https://dev.epicgames.com/documentation/en-us/fortnite/using-zipline-devices-in-fortnite-creative
• https://github.com/vz-creates/uefn
• https://github.com/vz-creates/uefn