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  5. Qt3DRender
  6. QLevelOfDetail

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>
CMake: find_package(Qt6 REQUIRED COMPONENTS 3drender)
target_link_libraries(mytarget PRIVATE Qt6::3drender)
qmake: QT += 3drender
实例化： LevelOfDetail
继承： Qt3DCore::QComponent
继承者：

Qt3DRender::QLevelOfDetailSwitch

公共类型

enum ThresholdType { DistanceToCameraThreshold, ProjectedScreenPixelSizeThreshold }

特性

公共函数

QLevelOfDetail (Qt3DCore::QNode * parent = nullptr)
Qt3DRender::QCamera * camera () const
int currentIndex () const
Qt3DRender::QLevelOfDetail::ThresholdType thresholdType () const
QList<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 QList<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 QList<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);
QList<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 : QList < 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：

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

通知程序信号：

void thresholdsChanged (const QList<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

[explicit] 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 QList < 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 .

内容