- Qt 5.15
- Qt 3D
- C++ Classes
- QSpotLight
- Qt 5.15.19 Reference Documentation

# QSpotLight Class

class Qt3DRender::QSpotLight

Encapsulate a Spot Light object in a Qt 3D scene. More...

Header: | #include <QSpotLight>
qmake: | QT += 3drender
Since: | Qt 5.5
Instantiated By: | SpotLight
Inherits: | Qt3DRender::QAbstractLight

This class was introduced in Qt 5.5.

- List of all members, including inherited members

## Properties

- constantAttenuation : float
- cutOffAngle : float
- linearAttenuation : float

- localDirection : QVector3D
- quadraticAttenuation : float

## Public Functions

| QSpotLight(Qt3DCore::QNode *parent = nullptr)
float | constantAttenuation() const
float | cutOffAngle() const
float | linearAttenuation() const
QVector3D | localDirection() const
float | quadraticAttenuation() const

## Public Slots

void | setConstantAttenuation(float value)
void | setCutOffAngle(float cutOffAngle)
void | setLinearAttenuation(float value)
void | setLocalDirection(const QVector3D &localDirection)
void | setQuadraticAttenuation(float value)

## Signals

void | constantAttenuationChanged(float constantAttenuation)
void | cutOffAngleChanged(float cutOffAngle)
void | linearAttenuationChanged(float linearAttenuation)
void | localDirectionChanged(const QVector3D &localDirection)
void | quadraticAttenuationChanged(float quadraticAttenuation)

## Detailed Description

A spotlight is a light source that emits a cone of light in a particular direction.

A spotlight uses three attenuation factors to describe how the intensity of the light decreases over distance. These factors are designed to be used together in calcuating total attenuation. For the materials in Qt3D Extras the following formula is used, where distance is the distance from the light to the surface being rendered:

     totalAttenuation = 1.0 / (constantAttenuation + (linearAttenuation * distance) + (quadraticAttenuation * distance * distance));

Custom materials may choose to interpret these factors differently.

## Property Documentation

### constantAttenuation : float

Specifies the constant attenuation of the spot light.

Note: The exact meaning and use of this property is up to the material implementation.

Access functions:

float | constantAttenuation() const
void | setConstantAttenuation(float value)

Notifier signal:

void | constantAttenuationChanged(float constantAttenuation)

### cutOffAngle : float

Specifies the cut off angle of the spot light.

Note: The exact meaning and use of this property is up to the material implementation.

Access functions:

float | cutOffAngle() const
void | setCutOffAngle(float cutOffAngle)

Notifier signal:

void | cutOffAngleChanged(float cutOffAngle)

### linearAttenuation : float

Specifies the linear attenuation of the spot light.

Note: The exact meaning and use of this property is up to the material implementation.

Access functions:

float | linearAttenuation() const
void | setLinearAttenuation(float value)

Notifier signal:

void | linearAttenuationChanged(float linearAttenuation)

### localDirection : QVector3D

Specifies the local direction of the spot light.

Note: The exact meaning and use of this property is up to the material implementation.

Access functions:

QVector3D | localDirection() const
void | setLocalDirection(const QVector3D &localDirection)

Notifier signal:

void | localDirectionChanged(const QVector3D &localDirection)

### quadraticAttenuation : float

Specifies the quadratic attenuation of the spot light.

Note: The exact meaning and use of this property is up to the material implementation.

Access functions:

float | quadraticAttenuation() const
void | setQuadraticAttenuation(float value)

Notifier signal:

void | quadraticAttenuationChanged(float quadraticAttenuation)

## Member Function Documentation

### QSpotLight::QSpotLight(Qt3DCore::QNode *parent = nullptr)

Constructs a new QSpotLight with the specified parent.