QLevelOfDetail Class

class Qt3DRender ::QLevelOfDetail

The QLevelOfDetail class provides a way of controlling the complexity of rendered entities based on their size on the screen. 更多...

头：	#include <QLevelOfDetail>
qmake:	QT += 3drender
Since:	Qt 5.9
实例化：	LevelOfDetail
继承：	Qt3DCore::QComponent
继承者：	Qt3DRender::QLevelOfDetailSwitch

该类在 Qt 5.9 引入。

所有成员列表，包括继承成员

公共类型

enum	ThresholdType { DistanceToCameraThreshold, ProjectedScreenPixelSizeThreshold }

特性

camera : Qt3DRender::QCamera*
currentIndex : int
thresholdType : ThresholdType

thresholds : QVector<qreal>
volumeOverride : Qt3DRender::QLevelOfDetailBoundingSphere

公共函数

	QLevelOfDetail (Qt3DCore::QNode * parent = nullptr)
Qt3DRender::QCamera *	camera () const
int	currentIndex () const
Qt3DRender::QLevelOfDetail::ThresholdType	thresholdType () const
QVector<qreal>	thresholds () const
Qt3DRender::QLevelOfDetailBoundingSphere	volumeOverride () const

公共槽

void	setCamera (Qt3DRender::QCamera * camera )
void	setCurrentIndex (int currentIndex )
void	setThresholdType (Qt3DRender::QLevelOfDetail::ThresholdType thresholdType )
void	setThresholds (const QVector<qreal> & thresholds )
void	setVolumeOverride (const Qt3DRender::QLevelOfDetailBoundingSphere & volumeOverride )

信号

void	cameraChanged (Qt3DRender::QCamera * camera )
void	currentIndexChanged (int currentIndex )
void	thresholdTypeChanged (Qt3DRender::QLevelOfDetail::ThresholdType thresholdType )
void	thresholdsChanged (const QVector<qreal> & thresholds )
void	volumeOverrideChanged (const Qt3DRender::QLevelOfDetailBoundingSphere & volumeOverride )

详细描述

QLevelOfDetail can be used to control the representation of an entity based on distance from the observer or size on the screen.

In order to improve rendering performance, objects that are very small can be rendered using far fewer details, in geometry or texture.

The component is controlled by specifying thresholds of values which are interpreted as either distances from the camera or screen size.

As the point of view changes, the currentIndex property will change to reflect matching value in the range array.

The currentIndex property can then be used, for example, to enable or disable entities, change material, etc.

The LevelOfDetail component is not shareable between multiple entities .

 #include <Qt3DCore/QEntity>
 #include <Qt3DRender/QGeometryRenderer>
 #include <Qt3DRender/QLevelOfDetail>
// Scene
Qt3DCore::QEntity *rootEntity = new Qt3DCore::Qt3DCore::QEntity;
Qt3DCore::QEntity *renderableEntity = new Qt3DCore::QEntity(rootEntity);
Qt3DRender::QGeometryRenderer *geometryRenderer = new Qt3DCore::QGeometryRenderer(renderableEntity);
renderableEntity->addComponent(geometryRenderer);
Qt3DRender::QLevelOfDetail* lod = new Qt3Render::QLevelOfDetail(renderableEntity);
QVector<qreal> thresholds = {20, 35, 50, 65};
lod->setThresholds(thresholds);
lod->setCamera(mainCamera);
renderableEntity->addComponent(lod);
// connect to QLevelOfDetail::currentIndexChanged to toggle rendering
...

成员类型文档编制

enum QLevelOfDetail:: ThresholdType

Specifies how the values in the thresholds are interpreted

常量	值	描述
`Qt3DRender::QLevelOfDetail::DistanceToCameraThreshold`	`0`	Distance from the entity to the selected camera
`Qt3DRender::QLevelOfDetail::ProjectedScreenPixelSizeThreshold`	`1`	Size of the entity when projected on the screen as seen from the selected camera, expressed in number of pixels on the side of the bounding square in screen space.

特性文档编制

camera : Qt3DRender::QCamera *

Holds the id of the camera that is used to compute the actual distance or the screen size.

访问函数：

Qt3DRender::QCamera *	camera () const
void	setCamera (Qt3DRender::QCamera * camera )

通知程序信号：

void	cameraChanged (Qt3DRender::QCamera * camera )

currentIndex : int

The index in the range array which matches the current distance to the camera or screen size.

访问函数：

int	currentIndex () const
void	setCurrentIndex (int currentIndex )

通知程序信号：

void	currentIndexChanged (int currentIndex )

thresholdType : ThresholdType

Specifies how range values are interpreted.

访问函数：

Qt3DRender::QLevelOfDetail::ThresholdType	thresholdType () const
void	setThresholdType (Qt3DRender::QLevelOfDetail::ThresholdType thresholdType )

通知程序信号：

void	thresholdTypeChanged (Qt3DRender::QLevelOfDetail::ThresholdType thresholdType )

另请参阅 Qt3DRender::QLevelOfDetail::ThresholdType .

thresholds : QVector < qreal >

Array of range values as float point numbers. The value for the most detailed representation should be specified first.

若 Qt3DRender::QLevelOfDetail::thresholdType 被设为 Qt3DRender::QLevelOfDetail::DistanceToCameraThreshold , values should be specified in ascending order, in camera space coordinates

若 Qt3DRender::QLevelOfDetail::thresholdType 被设为 Qt3DRender::QLevelOfDetail::ProjectedScreenPixelSizeThreshold , values should be specified in descending order, in screen space pixels.

访问函数：

QVector<qreal>	thresholds () const
void	setThresholds (const QVector<qreal> & thresholds )

通知程序信号：

void	thresholdsChanged (const QVector<qreal> & thresholds )

另请参阅 Qt3DRender::QLevelOfDetail::ThresholdType .

volumeOverride : Qt3DRender::QLevelOfDetailBoundingSphere

The default is a sphere of radius 1 and centered at the local origin of the entity. This proxy volume is used to compute the distance to the camera or the size of the screen projection.

If this value to nullptr, the bounding volume of the entity is used. Care must be taken that this bounding volume never becomes invalid.

访问函数：

Qt3DRender::QLevelOfDetailBoundingSphere	volumeOverride () const
void	setVolumeOverride (const Qt3DRender::QLevelOfDetailBoundingSphere & volumeOverride )

通知程序信号：

void	volumeOverrideChanged (const Qt3DRender::QLevelOfDetailBoundingSphere & volumeOverride )

另请参阅 Qt3DRender::QLevelOfDetailBoundingSphere .

成员函数文档编制

QLevelOfDetail:: QLevelOfDetail ( Qt3DCore::QNode * parent = nullptr)

Constructs a new QLevelOfDetail with the specified parent .

`[slot]` void QLevelOfDetail:: setCamera ( Qt3DRender::QCamera * camera )

设置 camera relative to which distance and size are computed.

注意： setter 函数对于特性 camera .

另请参阅 camera ().

`[slot]` void QLevelOfDetail:: setCurrentIndex ( int currentIndex )

设置 currentIndex .

注意： This should not normally be set by the user.

However, if the component is disabled, then changing the current index is a simple way of switching between multiple representations.

注意： setter 函数对于特性 currentIndex .

另请参阅 currentIndex ().

`[slot]` void QLevelOfDetail:: setThresholdType ( Qt3DRender::QLevelOfDetail::ThresholdType thresholdType )

Sets the way thresholds values are interpreted with parameter thresholdType

注意： setter 函数对于特性 thresholdType .

另请参阅 thresholdType () 和 Qt3DRender::QLevelOfDetail::ThresholdType .

`[slot]` void QLevelOfDetail:: setThresholds (const QVector < qreal > & thresholds )

Sets the range values in thresholds .

注意： setter 函数对于特性 thresholds .

另请参阅 thresholds () 和 Qt3DRender::QLevelOfDetail::thresholdType .

QLevelOfDetail Class

公共类型

特性

公共函数

公共槽

信号

详细描述

成员类型文档编制

enum QLevelOfDetail:: ThresholdType

特性文档编制

camera : Qt3DRender::QCamera *

currentIndex : int

thresholdType : ThresholdType

thresholds : QVector < qreal >

volumeOverride : Qt3DRender::QLevelOfDetailBoundingSphere

成员函数文档编制

QLevelOfDetail:: QLevelOfDetail ( Qt3DCore::QNode * parent = nullptr)

[slot] void QLevelOfDetail:: setCamera ( Qt3DRender::QCamera * camera )

[slot] void QLevelOfDetail:: setCurrentIndex ( int currentIndex )

[slot] void QLevelOfDetail:: setThresholdType ( Qt3DRender::QLevelOfDetail::ThresholdType thresholdType )

[slot] void QLevelOfDetail:: setThresholds (const QVector < qreal > & thresholds )

内容

`[slot]` void QLevelOfDetail:: setCamera ( Qt3DRender::QCamera * camera )

`[slot]` void QLevelOfDetail:: setCurrentIndex ( int currentIndex )

`[slot]` void QLevelOfDetail:: setThresholdType ( Qt3DRender::QLevelOfDetail::ThresholdType thresholdType )

`[slot]` void QLevelOfDetail:: setThresholds (const QVector < qreal > & thresholds )