Table of Contents

Spline Component

The spline component defines smooth curves in 3D space using cubic Bezier curves. Other components, such as the follow path component can use splines to animate objects, and scripts can sample spline data for custom logic.

How to Configure a Spline

  1. Add a game object and attach a spline component to it.

  2. Add several game objects as child objects (at least two).

  3. Attach a spline node component to each child object.

  4. Position the child objects in the world to form a spline. Enable the Visualize Spline flag to see a preview of the curve.

    Path hierarchy config

The spline uses the child objects in the order in which they appear in the scene hierarchy. To change the order of spline nodes, reorder the child objects in the scene tree. Node names do not need to be unique.

Editing Tips

When editing a spline you often need to select the child path nodes and then go back to the spline object. Ctrl+Q selects the parent object of the currently selected object, which is very useful here. Also Ctrl+B changes to the previous selection, which can also be used to undo a selection change.

The Edit Nodes manipulator is available both when the spline object itself is selected and when one of its child nodes is selected. This avoids having to switch back to the parent object to add or adjust nodes.

Adding Points Interactively

When the Edit Nodes manipulator is active, small gizmos appear at the midpoint of each spline segment. Click on a segment gizmo to insert a new spline node at that position. The new node is immediately selected.

Spline editing

To re-enable manipulator mode after translating an object, press Q to cycle back to the Edit Nodes manipulator, or click the toggle button next to the Edit Nodes property.

Editing Tangents

Each spline node can have its tangent mode set to Auto, Linear or Custom:

  • Auto: Tangents are computed automatically for smooth curvature.
  • Linear: Creates a sharp corner at the node with no curvature.
  • Custom: You can manually adjust the tangent direction and length using rotate and scale gizmos.

When using custom tangents, enable Link Custom Tangents to make the incoming and outgoing tangents mirror each other, creating a smooth transition through the point.

Spline Tangent Edit

Spline Features

Splines support interpolation of:

  • Position: Smooth cubic Bezier curve between nodes.
  • Rotation: Including a roll angle at each node.
  • Scale: Scale values can vary along the spline.
  • Up Direction: Computed from the roll angle for proper orientation.

What to do with a Spline

A spline component by itself has no functionality other than to define a shape. These component types can utilize splines:

Scripting with Splines

Visual scripts and C++ code can sample spline data using these functions:

  • GetPositionAtDistance(distance, space): Get position at a distance along the spline.
  • GetTransformAtDistance(distance, space): Get full transform including rotation and scale.
  • GetTotalLength(): Get the total length of the spline.
  • FindKeyClosestToPoint(point, space): Find the closest point on the spline to a given position.

The space parameter can be Local (relative to the spline) or Global (world space).

See the ScatterOnSpline sample script in the Testing Chambers project for an example of spawning objects along a spline.

Component Properties

  • Flags: Preview flags for the spline. Options include Visualize Spline, Visualize Up Dir, and Visualize Tangents.
  • Closed: Whether the spline should loop back to the first node.

Also see the spline node component for options on each node.

See Also

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