- Qt 6.6
- Qt Graphs
- C++ Classes
- QtGraphs (Technical Preview)
- QCustom3DVolume
- Qt Graphs | Commercial or GPLv3

# QCustom3DVolume Class

The QCustom3DVolume class adds a volume rendered object to a graph. More...

Header: | #include <QCustom3DVolume>
CMake: | find_package(Qt6 REQUIRED COMPONENTS Graphs) target_link_libraries(mytarget PRIVATE Qt6::Graphs)
qmake: | QT += graphs
Instantiated By: | Custom3DVolume
Inherits: | QCustom3DItem
Status: | Technical Preview

- List of all members, including inherited members

## Properties

alphaMultiplier : float colorTable : QList<QRgb> drawSliceFrames : bool drawSlices : bool preserveOpacity : bool sliceFrameColor : QColor sliceFrameGaps : QVector3D sliceFrameThicknesses : QVector3D sliceFrameWidths : QVector3D | sliceIndexX : int sliceIndexY : int sliceIndexZ : int textureData : QList<uchar>* textureDepth : int textureHeight : int textureWidth : int useHighDefShader : bool

## Public Functions

| QCustom3DVolume(QObject *parent = nullptr)
| QCustom3DVolume(const QVector3D &position, const QVector3D &scaling, const QQuaternion &rotation, int textureWidth, int textureHeight, int textureDepth, QList<uchar> *textureData, QImage::Format textureFormat, const QList<QRgb> &colorTable, QObject *parent = nullptr)
virtual | ~QCustom3DVolume()
float | alphaMultiplier() const
QList<QRgb> | colorTable() const
QList<uchar> * | createTextureData(const QList<QImage *> &images)
bool | drawSliceFrames() const
bool | drawSlices() const
bool | preserveOpacity() const
QImage | renderSlice(Qt::Axis axis, int index)
void | setAlphaMultiplier(float mult)
void | setColorTable(const QList<QRgb> &colors)
void | setDrawSliceFrames(bool enable)
void | setDrawSlices(bool enable)
void | setPreserveOpacity(bool enable)
void | setSliceFrameColor(const QColor &color)
void | setSliceFrameGaps(const QVector3D &values)
void | setSliceFrameThicknesses(const QVector3D &values)
void | setSliceFrameWidths(const QVector3D &values)
void | setSliceIndexX(int value)
void | setSliceIndexY(int value)
void | setSliceIndexZ(int value)
void | setSliceIndices(int x, int y, int z)
void | setSubTextureData(Qt::Axis axis, int index, const uchar *data)
void | setSubTextureData(Qt::Axis axis, int index, const QImage &image)
void | setTextureData(QList<uchar> *data)
void | setTextureDepth(int value)
void | setTextureDimensions(int width, int height, int depth)
void | setTextureFormat(QImage::Format format)
void | setTextureHeight(int value)
void | setTextureWidth(int value)
void | setUseHighDefShader(bool enable)
QColor | sliceFrameColor() const
QVector3D | sliceFrameGaps() const
QVector3D | sliceFrameThicknesses() const
QVector3D | sliceFrameWidths() const
int | sliceIndexX() const
int | sliceIndexY() const
int | sliceIndexZ() const
QList<uchar> * | textureData() const
int | textureDataWidth() const
int | textureDepth() const
QImage::Format | textureFormat() const
int | textureHeight() const
int | textureWidth() const
bool | useHighDefShader() const

## Signals

void | alphaMultiplierChanged(float mult)
void | colorTableChanged()
void | drawSliceFramesChanged(bool enabled)
void | drawSlicesChanged(bool enabled)
void | preserveOpacityChanged(bool enabled)
void | sliceFrameColorChanged(const QColor &color)
void | sliceFrameGapsChanged(const QVector3D &values)
void | sliceFrameThicknessesChanged(const QVector3D &values)
void | sliceFrameWidthsChanged(const QVector3D &values)
void | sliceIndexXChanged(int value)
void | sliceIndexYChanged(int value)
void | sliceIndexZChanged(int value)
void | textureDataChanged(QList<uchar> *data)
void | textureDepthChanged(int value)
void | textureFormatChanged(QImage::Format format)
void | textureHeightChanged(int value)
void | textureWidthChanged(int value)
void | useHighDefShaderChanged(bool enabled)

## Detailed Description

A volume rendered object is a box with a 3D texture. Three slice planes are supported for the volume, one along each main axis of the volume.

Rendering volume objects is very performance intensive, especially when the volume is largely transparent, as the contents of the volume are ray-traced. The performance scales nearly linearly with the amount of pixels that the volume occupies on the screen, so showing the volume in a smaller view or limiting the zoom level of the graph are easy ways to improve performance. Similarly, the volume texture dimensions have a large impact on performance. If the frame rate is more important than pixel-perfect rendering of the volume contents, consider turning the high definition shader off by setting the useHighDefShader property to `false`.

Note: Volumetric objects are only supported with orthographic projection.

Note: Volumetric objects utilize 3D textures, which are not supported in OpenGL ES2 environments.

See also QAbstract3DGraph::addCustomItem(), QAbstract3DGraph::orthoProjection, and useHighDefShader.

## Property Documentation

### alphaMultiplier : float

This property holds the value that the alpha value of every texel of the volume texture is multiplied with at the render time.

This property can be used to introduce uniform transparency to the volume. If preserveOpacity is `true`, only texels with at least some transparency to begin with are affected, and fully opaque texels are not affected. The value must not be negative. Defaults to `1.0f`.

Access functions:

float | alphaMultiplier() const
void | setAlphaMultiplier(float mult)

Notifier signal:

void | alphaMultiplierChanged(float mult)

See also preserveOpacity and textureData.

### colorTable : QList<QRgb>

This property holds the array containing the colors for indexed texture formats.

If the texture format is not indexed, this array is not used and can be empty.

Defaults to `0`.

Access functions:

QList<QRgb> | colorTable() const
void | setColorTable(const QList<QRgb> &colors)

Notifier signal:

void | colorTableChanged()

See also textureData, setTextureFormat(), and QImage::colorTable().

### drawSliceFrames : bool

This property holds whether slice frames are drawn around the volume.

If this property value is `true`, the frames of slices indicated by slice index properties will be drawn around the volume. If it is `false`, no slice frames will be drawn.

Drawing slice frames is independent of drawing slices, so you can show the full volume and still draw the slice frames around it. This is useful when using renderSlice() to display the slices outside the graph itself.

Defaults to `false`.

Access functions:

bool | drawSliceFrames() const
void | setDrawSliceFrames(bool enable)

Notifier signal:

void | drawSliceFramesChanged(bool enabled)

See also sliceIndexX, sliceIndexY, sliceIndexZ, drawSlices, and renderSlice().

### drawSlices : bool

This property holds whether the specified slices are drawn instead of the full volume.

If this property value is `true`, the slices indicated by slice index properties will be drawn instead of the full volume. If it is `false`, the full volume will always be drawn. Defaults to `false`.

Note: The slices are always drawn along the item axes, so if the item is rotated, the slices are rotated as well.

Access functions:

bool | drawSlices() const
void | setDrawSlices(bool enable)

Notifier signal:

void | drawSlicesChanged(bool enabled)

See also sliceIndexX, sliceIndexY, and sliceIndexZ.

### preserveOpacity : bool

This property holds whether the alpha multiplier is applied to all texels.

If this property value is `true`, alphaMultiplier is only applied to texels that already have some transparency. If it is `false`, the multiplier is applied to the alpha value of all texels. Defaults to `true`.

Access functions:

bool | preserveOpacity() const
void | setPreserveOpacity(bool enable)

Notifier signal:

void | preserveOpacityChanged(bool enabled)

See also alphaMultiplier.

### sliceFrameColor : QColor

This property holds the color of the slice frame.

Transparent slice frame color is not supported.

Defaults to black.

Access functions:

QColor | sliceFrameColor() const
void | setSliceFrameColor(const QColor &color)

Notifier signal:

void | sliceFrameColorChanged(const QColor &color)

See also drawSliceFrames.

### sliceFrameGaps : QVector3D

This property holds the size of the air gap left between the volume itself and the frame in each dimension.

The gap can be different on different dimensions. The values are fractions of the volume thickness in the same dimension. The values cannot be negative.

Defaults to `QVector3D(0.01, 0.01, 0.01)`.

Access functions:

QVector3D | sliceFrameGaps() const
void | setSliceFrameGaps(const QVector3D &values)

Notifier signal:

void | sliceFrameGapsChanged(const QVector3D &values)

See also drawSliceFrames.

### sliceFrameThicknesses : QVector3D

This property holds the thickness of the slice frames for each dimension.

The values are fractions of the volume thickness in the same dimension. The values cannot be negative.

Defaults to `QVector3D(0.01, 0.01, 0.01)`.

Access functions:

QVector3D | sliceFrameThicknesses() const
void | setSliceFrameThicknesses(const QVector3D &values)

Notifier signal:

void | sliceFrameThicknessesChanged(const QVector3D &values)

See also drawSliceFrames.

### sliceFrameWidths : QVector3D

This property holds the width of the slice frame.

The width can be different on different dimensions, so you can for example omit drawing the frames on certain sides of the volume by setting the value for that dimension to zero. The values are fractions of the volume thickness in the same dimension. The values cannot be negative.

Defaults to `QVector3D(0.01, 0.01, 0.01)`.

Access functions:

QVector3D | sliceFrameWidths() const
void | setSliceFrameWidths(const QVector3D &values)

Notifier signal:

void | sliceFrameWidthsChanged(const QVector3D &values)

See also drawSliceFrames.

### sliceIndexX : int

This property holds the x-dimension index into the texture data indicating which vertical slice to show.

Setting any dimension to negative indicates no slice or slice frame for that dimension is drawn. If all dimensions are negative, no slices or slice frames are drawn and the volume is drawn normally.

Defaults to `-1`.

Access functions:

int | sliceIndexX() const
void | setSliceIndexX(int value)

Notifier signal:

void | sliceIndexXChanged(int value)

See also textureData, drawSlices, and drawSliceFrames.

### sliceIndexY : int

This property holds the y-dimension index into the texture data indicating which horizontal slice to show.

Setting any dimension to negative indicates no slice or slice frame for that dimension is drawn. If all dimensions are negative, no slices or slice frames are drawn and the volume is drawn normally.

Defaults to `-1`.

Access functions:

int | sliceIndexY() const
void | setSliceIndexY(int value)

Notifier signal:

void | sliceIndexYChanged(int value)

See also textureData, drawSlices, and drawSliceFrames.

### sliceIndexZ : int

This property holds the z-dimension index into the texture data indicating which vertical slice to show.

Setting any dimension to negative indicates no slice or slice frame for that dimension is drawn. If all dimensions are negative, no slices or slice frames are drawn and the volume is drawn normally.

Defaults to `-1`.

Access functions:

int | sliceIndexZ() const
void | setSliceIndexZ(int value)

Notifier signal:

void | sliceIndexZChanged(int value)

See also textureData, drawSlices, and drawSliceFrames.

### textureData : QList<uchar>*

This property holds the array containing the texture data in the format specified by textureFormat.

The size of this array must be at least (`textureDataWidth * textureHeight * textureDepth * texture format color depth in bytes`).

A 3D texture is defined by a stack of 2D subtextures. Each subtexture must be of identical size (`textureDataWidth * textureHeight`), and the depth of the stack is defined by the textureDepth property. The data in each 2D texture is identical to a QImage data with the same format, so QImage::bits() can be used to supply the data for each subtexture.

Ownership of the new array transfers to the QCustom3DVolume instance. If another array is set, the previous array is deleted. If the same array is set again, it is assumed that the array contents have been changed and the graph rendering is triggered.

Note: Each x-dimension line of the data needs to be 32-bit aligned. If textureFormat is QImage::Format_Indexed8 and the textureWidth value is not divisible by four, padding bytes might need to be added to each x-dimension line of the data. The textureDataWidth() function returns the padded byte count. The padding bytes should indicate a fully transparent color to avoid rendering artifacts.

Defaults to `0`.

Access functions:

QList<uchar> * | textureData() const
void | setTextureData(QList<uchar> *data)

Notifier signal:

void | textureDataChanged(QList<uchar> *data)

See also colorTable, setTextureFormat(), setSubTextureData(), and textureDataWidth().

### textureDepth : int

This property holds the depth of the 3D texture defining the volume content in pixels.

Defaults to `0`.

Note: The textureData value may need to be resized or recreated if this value is changed. Defaults to `0`.

Access functions:

int | textureDepth() const
void | setTextureDepth(int value)

Notifier signal:

void | textureDepthChanged(int value)

See also textureData, textureWidth, textureHeight, and setTextureFormat().

### textureHeight : int

This property holds the height of the 3D texture defining the volume content in pixels.

Defaults to `0`.

Note: The textureData value may need to be resized or recreated if this value is changed. Defaults to `0`.

Access functions:

int | textureHeight() const
void | setTextureHeight(int value)

Notifier signal:

void | textureHeightChanged(int value)

See also textureData, textureWidth, textureDepth, and setTextureFormat().

### textureWidth : int

This property holds the width of the 3D texture defining the volume content in pixels.

Defaults to `0`.

Note: The textureData value may need to be resized or recreated if this value is changed. Defaults to `0`.

Access functions:

int | textureWidth() const
void | setTextureWidth(int value)

Notifier signal:

void | textureWidthChanged(int value)

See also textureData, textureHeight, textureDepth, setTextureFormat(), and textureDataWidth().

### useHighDefShader : bool

This property holds whether a high or low definition shader is used to render the volume.

If this property value is `true`, a high definition shader is used. If it is `false`, a low definition shader is used.

The high definition shader guarantees that every visible texel of the volume texture is sampled when the volume is rendered. The low definition shader renders only a rough approximation of the volume contents, but at a much higher frame rate. The low definition shader does not guarantee that every texel of the volume texture is sampled, so there may be flickering if the volume contains distinct thin features.

Note: This value does not affect the level of detail when rendering the slices of the volume.

Defaults to `true`.

Access functions:

bool | useHighDefShader() const
void | setUseHighDefShader(bool enable)

Notifier signal:

void | useHighDefShaderChanged(bool enabled)

See also renderSlice().

## Member Function Documentation

### `[explicit]` QCustom3DVolume::QCustom3DVolume(QObject *parent = nullptr)

Constructs a custom 3D volume with the given parent.

### `[explicit]` QCustom3DVolume::QCustom3DVolume(const QVector3D &position, const QVector3D &scaling, const QQuaternion &rotation, int textureWidth, int textureHeight, int textureDepth, QList<uchar> *textureData, QImage::Format textureFormat, const QList<QRgb> &colorTable, QObject *parent = nullptr)

Constructs a custom 3D volume with the given position, scaling, rotation, textureWidth, textureHeight, textureDepth, textureData, textureFormat, colorTable, and optional parent.

See also textureData, setTextureFormat(), and colorTable.

### `[virtual noexcept]` QCustom3DVolume::~QCustom3DVolume()

Deletes the custom 3D volume.

### QList<uchar> *QCustom3DVolume::createTextureData(const QList<QImage *> &images)

Creates a new texture data array from an array of images and sets it as textureData for this volume object. The texture dimensions are also set according to image and array dimensions. All of the images in the array must be the same size. If the images are not all in the QImage::Format_Indexed8 format, all texture data will be converted into the QImage::Format_ARGB32 format. If the images are in the QImage::Format_Indexed8 format, the colorTable value for the entire volume will be taken from the first image.

Returns a pointer to the newly created array.

See also textureData, textureWidth, textureHeight, textureDepth, and setTextureFormat().

### QImage QCustom3DVolume::renderSlice(Qt::Axis axis, int index)

Renders the slice specified by index along the axis specified by axis into an image. The texture format of this object is used.

Returns the rendered image of the slice, or a null image if an invalid index is specified.

See also setTextureFormat().

### void QCustom3DVolume::setSliceIndices(int x, int y, int z)

A convenience function for setting all three slice indices (x, y, and z) at once.

See also textureData.

### void QCustom3DVolume::setSubTextureData(Qt::Axis axis, int index, const uchar *data)

Sets a single 2D subtexture of the 3D texture along the specified axis of the volume. The index parameter specifies the subtexture to set. The texture data must be in the format specified by the textureFormat property and have the size of the cross-section of the volume texture along the specified axis multiplied by the texture format color depth in bytes. The data is expected to be ordered similarly to the data in images produced by the renderSlice() method along the same axis.

Note: Each x-dimension line of the data needs to be 32-bit aligned when targeting the y-axis or z-axis. If textureFormat is QImage::Format_Indexed8 and the textureWidth value is not divisible by four, padding bytes might need to be added to each x-dimension line of the data to properly align it. The padding bytes should indicate a fully transparent color to avoid rendering artifacts.

See also textureData and renderSlice().

### void QCustom3DVolume::setSubTextureData(Qt::Axis axis, int index, const QImage &image)

Sets a single 2D subtexture of the 3D texture along the specified axis of the volume. The index parameter specifies the subtexture to set. The source image must be in the format specified by the textureFormat property if textureFormat is indexed. If textureFormat is QImage::Format_ARGB32, the image is converted to that format. The image must have the size of the cross-section of the volume texture along the specified axis. The orientation of the image should correspond to the orientation of the slice image produced by renderSlice() method along the same axis.

Note: Each x-dimension line of the data needs to be 32-bit aligned when targeting the y-axis or z-axis. If textureFormat is QImage::Format_Indexed8 and the textureWidth value is not divisible by four, padding bytes might need to be added to each x-dimension line of the image to properly align it. The padding bytes should indicate a fully transparent color to avoid rendering artifacts. It is not guaranteed that QImage will do this automatically.

See also textureData and renderSlice().

### void QCustom3DVolume::setTextureDimensions(int width, int height, int depth)

A convenience function for setting all three texture dimensions (width, height, and depth) at once.

See also textureData.

### void QCustom3DVolume::setTextureFormat(QImage::Format format)

Sets the format of the textureData property to format. Only two formats are supported currently: QImage::Format_Indexed8 and QImage::Format_ARGB32. If an indexed format is specified, colorTable must also be set. Defaults to QImage::Format_ARGB32.

See also textureFormat(), colorTable, and textureData.

### int QCustom3DVolume::textureDataWidth() const

Returns the actual texture data width. When the texture format is QImage::Format_Indexed8, this value equals textureWidth aligned to a 32-bit boundary. Otherwise, this value equals four times textureWidth.

### QImage::Format QCustom3DVolume::textureFormat() const

Returns the format of the textureData property value.

See also setTextureFormat().

### `[signal]` void QCustom3DVolume::textureFormatChanged(QImage::Format format)

This signal is emitted when the format of the textureData value changes.

See also setTextureFormat().