3D bar chart item with VBO/VAO rendering More...

#include <qwt3d_bar.h>

Inheritance diagram for Qwt3DBar:

Classes
class	PrivateData

Public Types
enum	BarStyle { Filled , FilledMesh , Wireframe }
	Bar rendering style. More...

Public Member Functions
	Qwt3DBar ()
	Constructs an empty bar chart item.

	~Qwt3DBar () override
	Destructor — releases GL resources and data.

void	setSamples (const QVector< QwtPoint3D > &samples)
	Set bar positions and heights from 3D points (x,y = footprint center, z = height)

void	setSamples (const QVector< double > &x, const QVector< double > &heights)
	Set bar positions (x) and heights along the y = 0 row.

void	setSamples (double **z, int columns, int rows, double minX, double maxX, double minY, double maxY)
	Set a grid of bars from a z-value matrix with an explicit x/y domain.

void	setSamples (const Qwt3DFunctionData &data)
	Set a grid of bars from a Qwt3DFunctionData result (modern vector API)

double	barWidth () const
	Returns the bar footprint width (<= 0 means auto)

void	setBarWidth (double w)
	Sets the bar footprint width (<= 0 selects auto = 80% of spacing)

double	barDepth () const
	Returns the bar footprint depth (<= 0 means auto)

void	setBarDepth (double d)
	Sets the bar footprint depth (<= 0 selects auto = 80% of spacing)

double	baseline () const
	Returns the baseline z value (bottom of positive bars)

void	setBaseline (double z)
	Sets the baseline z value.

BarStyle	barStyle () const
	Returns the bar rendering style.

void	setBarStyle (BarStyle style)
	Sets the bar rendering style.

void	setDataColor (Qwt3DColor *color)
	Sets the data color functor (takes ownership)

const Qwt3DColor *	dataColor () const
	Returns the data color functor.

void	invalidateColors ()
	Marks per-vertex colors as stale, triggering a VBO rebuild on the next draw.

RGBA	meshColor () const
	Returns the mesh line color.

void	setMeshColor (RGBA color)
	Sets the mesh line color.

double	meshLineWidth () const
	Returns the mesh line width.

void	setMeshLineWidth (double width)
	Sets the mesh line width.

int	rtti () const override
	运行时类型信息

void	draw () override
	Draw the item using the current GL context.

ParallelEpiped	hull () const override
	Get the bounding hull of the item in 3D space.

void	populateLegendColors (ColorVector &colors) const override
	Populate the legend color vector from the item's color functor.

QVector< QwtPoint3D >	samples () const
	Returns 1D bar samples (empty if 2D grid data was loaded)

bool	isGridData () const
	Returns true if 2D grid data was loaded.

int	gridColumns () const
	Returns grid columns (valid only if isGridData())

int	gridRows () const
	Returns grid rows (valid only if isGridData())

double	gridMinX () const
	Returns grid x minimum (valid only if isGridData())

double	gridMaxX () const
	Returns grid x maximum (valid only if isGridData())

double	gridMinY () const
	Returns grid y minimum (valid only if isGridData())

double	gridMaxY () const
	Returns grid y maximum (valid only if isGridData())

std::vector< std::vector< double > >	gridZValues () const
	Returns the raw z matrix (valid only if isGridData(), empty otherwise)

Public Member Functions inherited from Qwt3DPlotItem
	Qwt3DPlotItem ()
	Default constructor.

virtual	~Qwt3DPlotItem ()
	Destructor — detaches from any plot.

void	attach (Qwt3DPlot *plot)
	Attach the item to a plot.

void	detach ()
	Detach the item from its plot.

Qwt3DPlot *	plot () const
	Get the plot this item is attached to.

void	setTitle (const QString &title)
	Set the item title.

QString	title () const
	Get the item title.

void	setZ (double z)
	Set the z-order value (controls draw sequence)

double	z () const
	Get the z-order value.

void	setVisible (bool on)
	Set item visibility.

bool	isVisible () const
	Check if the item is visible.

virtual void	itemChanged ()
	Notify the plot that the item has changed.

Detailed Description

3D bar chart item with VBO/VAO rendering

Qwt3DBar is a Qwt3DPlotItem that renders 3D bar chart data using modern OpenGL (VBO/VAO + GLSL shaders). Each sample becomes an axis-aligned cuboid ("bar") whose height encodes the scalar value.

Two data shapes are supported:

A 1D series of bars placed freely on the xy-plane (setSamples with QwtPoint3D, where (x,y) is the footprint center and z is the bar height).
A 2D grid of bars (bar3 / 3D histogram) sampled over a rectangular x/y domain, where z[i][j] is the height at cell (i,j).

The item manages its own bar specifications, color mapping, and GL resources (VBO, VAO, EBO, shader program). Geometry is uploaded to GPU memory when dirty and reused across frames until the data changes.

Bars reuse the lit surface shader (Blinn-Phong) with flat per-face normals, so they respond to Qwt3DPlot::enableLighting(). An optional edge mesh is drawn in a second pass for the FilledMesh / Wireframe styles.

auto plot = new Qwt3DPlot(parent);
 
auto bars = new Qwt3DBar();
bars->setSamples(zMatrix, columns, rows, minX, maxX, minY, maxY);
bars->setBarStyle(Qwt3DBar::FilledMesh);
bars->setDataColor(new Qwt3DColorMapColor("viridis"));
bars->attach(plot);

See also: Qwt3DPlotItem, Qwt3DPlot, Qwt3DColor

Member Enumeration Documentation

◆ BarStyle

enum Qwt3DBar::BarStyle

Bar rendering style.

Enumerator
Filled	Filled bars, no edges.
FilledMesh	Filled bars with separately colored edge lines.
Wireframe	Edge lines only.

Member Function Documentation

◆ draw()

void Qwt3DBar::draw ( )

overridevirtual

Draw the item using the current GL context.

Implements Qwt3DPlotItem.

◆ hull()

ParallelEpiped Qwt3DBar::hull ( ) const

overridevirtual

Get the bounding hull of the item in 3D space.

Implements Qwt3DPlotItem.

◆ populateLegendColors()

void Qwt3DBar::populateLegendColors ( ColorVector & colors ) const

overridevirtual

Populate the legend color vector from the item's color functor.

Reimplemented from Qwt3DPlotItem.

◆ rtti()

int Qwt3DBar::rtti ( ) const

overridevirtual

运行时类型信息

Returns: Rtti_Plot3DBar (= 1002)

Reimplemented from Qwt3DPlotItem.

◆ samples()

QVector< QwtPoint3D > Qwt3DBar::samples ( ) const

Returns 1D bar samples (empty if 2D grid data was loaded)

Reconstructs QVector<QwtPoint3D> from internal bar specs.

The documentation for this class was generated from the following files:

/home/runner/work/QWT/QWT/src/plot3d/qwt3d_bar.h
/home/runner/work/QWT/QWT/src/plot3d/qwt3d_bar.cpp

Classes

Public Types

Public Member Functions

Detailed Description

Member Enumeration Documentation

◆ BarStyle

Member Function Documentation

◆ draw()

◆ hull()

◆ populateLegendColors()

◆ rtti()

◆ samples()