# Spline populator

A spline is a [populator](/build/populators.md) shape. Pick the spline shape on a populator and you get a curve along which the populator's objects distribute. Useful for fences, hedges, roads, walls of crowd extras, lamp posts, or any element that repeats along a path.

![Build mode with a spline-shaped populator running through a dense tropical forest. The spline curve is visible as a white line with control-point markers, distributing road tiles along the path](/files/8JGzQjUCmdu7wpR00lGZ)

## What it does

Most populator shapes distribute objects across an area – a forest in a polygon, parade-goers in a rectangle. The spline shape distributes along a curve instead. Set the path; the populator places its objects along it at intervals you control.

The pattern shows up in real production constantly: a fence around a yard, a road through a town, a hedge along a property line, lamp posts down a street. Authoring each as a separate placed asset is tedious. A spline populator places them all at once, and editing the spline updates the layout live.

## How to use it

{% stepper %}
{% step %}

#### Create a populator

Build mode → add a populator. The populator appears with the default shape.
{% endstep %}

{% step %}

#### Set the shape to spline

In the populator's properties panel, find the **Shape** field. Pick **Spline**. The populator's footprint switches to a curve with editable handles.
{% endstep %}

{% step %}

#### Pick the element to distribute

Set the populator's element to the asset you want repeated along the curve – a fence segment, a road tile, a lamp post, a tree. The populator places one instance per spline segment by default.
{% endstep %}

{% step %}

#### Edit the curve

Double-click the populator to enter spline-edit mode. The curve's control handles become interactive. Use the in-app shortcuts (visible in the Keyboard Shortcuts panel) to add, move, or remove handles along the curve. Double-click the populator again to exit spline-edit mode and return to normal selection.
{% endstep %}

{% step %}

#### Adjust object orientation if needed

The populator places each object using the asset's native rotation. Some assets face the wrong direction by default for spline use (fence segments designed front-on need to be rotated to face along the curve). Open the populator's element properties and adjust the rotation field. Common case: setting rotation to 90° aligns a fence segment's long axis with the spline.
{% endstep %}
{% endstepper %}

## Roads

Roads are a special variant of the spline populator. Add a road and you get a road segment along the spline; the rest of the editing flow is identical to the spline workflow above.

## When to reach for it

* **Linear repeating elements.** Fences, hedges, walls, lamp posts, road tiles, signage along a route.
* **A path through a scene.** A road, a sidewalk, a river bank where you want consistent objects placed along it.
* **Layouts that need to follow terrain.** Curves that bend with the ground, where placing each object by hand would mean fighting the geometry.

When not to reach for it:

* **Area distribution.** A forest, a crowd in a square, scattered debris – use a regular polygon-shape populator.
* **Single-object placement.** One bench in a park doesn't need a populator; just place it.

## Common mistakes

* **Trying to edit the curve without entering spline-edit mode.** Selecting the populator shows handles, but editing them needs the explicit double-click into edit mode. Without it, drags will move the populator's whole footprint instead of reshaping the curve.
* **Wrong-facing assets.** A fence segment that looks great in isolation may face perpendicular to the spline when placed. Fix in the populator's element rotation field, not by re-authoring the asset.

## Related

* [Populators](/build/populators.md)
* [Asset library](/build/asset-library.md)
* [Smart Import](/build/import-your-own-models.md)


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