---
title: "Clip planes"
canonical: "https://help.twinfinity.com/space/HCFD/1098743810/Clip%20planes"
format: markdown
---
Clip planes (also called *cut planes*) let you slice through your 3D model to reveal what's inside. Instead of hiding entire objects, a cut plane removes everything on one side of an infinite plane. This makes it easy to explore interiors, check alignments, and communicate design intent.

## How it works

A cut plane is defined by two things:

- **Point** — a position in the model that the plane passes through.
- **Normal vector** — the direction the plane faces; this controls which side stays visible.

Geometry on the clipped side of the plane is hidden. The exposed surface can be tinted with a solid colour or given a soft *fade size* for clarity.

A clip plane is set by a point it passes through and the direction it faces. The `clipPlaneIndex` names it so you can move or disable it later — there are six slots: `clipPlane` and `clipPlane2` through `clipPlane6`.

```ts
const options: ClipPlaneOptions = {
  clipPlaneIndex: 'clipPlane',
  enabled: true,
  normalVector: new Vector3(-1, 0, 0), // which way the plane faces — flip to (1,0,0) to keep the other side
  point: new Vector3(45, 0, 0), // a point on the plane, in model units
  color: Color3.Black(), // colours the cut surface so it stands out
  fadeSize: 0.1 // width of the coloured band on the cut, set to 0 to drop it
};

api.viewer.setClipPlane(options);
```

See it in the playground: [Clip plane](https://playground.twinfinity.dev/?pgId=clip-planes/single-plane).

## Typical uses

- Slice through floors to see room layouts.
- Create cross-sections for structural inspection.
- Hide outer walls to explore building interiors.

## Controlling cut planes

- Multiple planes can be added, moved, or disabled.
- Individual objects (for example, floors or reference geometry) can be excluded so they are never cut. See [Exclude objects from clipping](https://playground.twinfinity.dev/?pgId=clip-planes/exclude-objects).
- Colours and fade settings can be adjusted to improve readability.

## Tips and best practices

- **Disable backface culling.** Cutting into a solid means you end up looking at the back of its faces, so turn off backface culling or the cut looks hollow. This gives a more realistic cross-section view.
- **Exclude key objects.** Set `ignoreClipPlanes = true` on elements like floors or reference meshes if you want them always visible as context. See [Exclude objects from clipping](https://playground.twinfinity.dev/?pgId=clip-planes/exclude-objects).
- **Use strong contrast.** Pick a cut colour (for example black or bright red) that stands out against the model materials.
- **Slide the plane.** Moving the plane point along an axis is a quick way to "scroll" through your model.
- **Flip the normal.** Inverting the normal vector instantly switches which side is clipped — useful for quickly changing perspective.
- **Combine planes.** Multiple cut planes can intersect, allowing box-like sections or very focused slices.

## See also

- [Clip plane with section fills](https://playground.twinfinity.dev/?pgId=clip-planes/section-fills)
- [Cross-sections](https://twinfinity.atlassian.net/wiki/spaces/HCFD/pages/1655439366/Cross-sections) — clip planes hide a side; cross-sections compute the actual cut drawing.