---
title: "PxrFacingRatio"
canonical: "https://rmanwiki-25.pixar.com/space/REN25/20416252/PxrFacingRatio"
format: markdown
---
Computes the facing ratio of the geometry: a simple dot product between the camera vector or direction and the surface normal. Note that some scene entities do not have a defined normal, like volumes.

### Input Parameters

#### Use

Choose the rendering camera direction or a predefined direction

#### Direction

Supply a direction vector when not using the camera direction

#### Coordinate System

Supply a useful coordinate system, object, world, camera, or other defined space.

#### Face Forward

The facing ratio can be negative if the normal is pointing away from the camera. This will flip the normal to always give a positive result.

#### Clamp

Clamp the result from 0 to 1

#### Invert

Inverts the facing ratio: black becomes white and vice-versa.

#### Mode

Choose between specifying an Ior or Gamma

#### Ior

When using the Ior mode set above, choose an index of refraction value, typically 1.0 to 3.0, useful for simulating a dielectric surface.

#### Gamma

When using the gamma node set above, a simple gamma function to shape the facing ratio. A value of 1.0 is neutral

#### Bump Normal

If the surface is bump-mapped, input the bump normal here. If not connected, the node will use this shading normal.

### Output Parameters

#### resultF

The single-component (float) value produced by the facing ratio computation.