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3D Plot Introduction

Qwt 7.1 integrates the original QwtPlot3D library, providing 3D data visualization capabilities. The 3D plot module supports surface plots, grid plots, function plots, and other types, suitable for 3D data display in scientific computing and engineering analysis.

Main Features

Features

  • ✅ Multiple plot types: Surface plots, grid plots, parametric surfaces, etc.
  • ✅ OpenGL rendering: High-performance 3D rendering using OpenGL
  • ✅ Interactive operations: Supports mouse rotation, zooming, and panning
  • ✅ Lighting and materials: Supports lighting effects and material configuration
  • ✅ Theme system: One-click visual style switching with 10 preset themes and 22 scientific colormaps

3D Plot Module Structure

classDiagram
    class Plot3D {
        +setCoordinateStyle()
        +setPlotStyle()
        +setRotation()
        +setScale()
        +updateData()
        +enableMouse()
        +showColorLegend()
        +setDataColor()
    }

    class SurfacePlot {
        +loadFromData()
        +setResolution()
    }

    class Function {
        +operator(x,y)
        +create()
        +setDomain()
        +setMesh()
    }

    Plot3D <|-- SurfacePlot
    Plot3D --> Function : uses

Namespace

All 3D classes live in the Qwt3D namespace. Below they are shown without the
Qwt3D:: prefix for brevity — qualify them (or add using namespace Qwt3D;) in your code.

Core Classes

Class Name Description
Qwt3D::Plot3D 3D plot base class, provides basic framework and interaction
Qwt3D::SurfacePlot 3D surface plot, displays continuous surfaces (handles both grid and cell data)
Qwt3D::Function 3D function plot, generates surfaces from mathematical functions
Qwt3D::GraphPlot Intermediate base class for graph-based 3D plots
Qwt3D::Axis 3D axis configuration
Qwt3D::ColorLegend 3D color bar
Qwt3D::Qwt3DTheme 3D theme system, encapsulates background, mesh, colormap, axes, lighting, and all visual attributes

Usage

The 3D plot example is located at: examples/3D/simpleplot3D. Screenshot:

simpleplot3D

Basic Usage Example

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#include <qwt3d_surfaceplot.h>
#include <qwt3d_function.h>

using namespace Qwt3D;

// Create surface plot
SurfacePlot* plot = new SurfacePlot();

// Define function
class MyFunction : public Function
{
public:
    double operator()(double x, double y) override
    {
        return std::sin(x) * std::cos(y);  // Mathematical function
    }
};

// Create function object and assign it to the plot
MyFunction* func = new MyFunction(*plot);

// Set data range and mesh resolution
func->setDomain(-5, 5, -5, 5);  // x and y range
func->setMesh(50, 50);           // 50x50 grid

// Create surface
func->create();

// Set rotation angles
plot->setRotation(30, 0, 45);  // X, Y, Z axis rotation angles

// Display
plot->show();

Data Loading

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#include <qwt3d_surfaceplot.h>

using namespace Qwt3D;

// Load from data array
SurfacePlot* plot = new SurfacePlot();

// Allocate a 100x100 Z value array
double* zData[100];
for (int i = 0; i < 100; ++i)
    zData[i] = new double[100];
// ... fill data ...

// Load Z value data with explicit X/Y range
plot->loadFromData(zData, 100, 100, 0.0, 100.0, 0.0, 100.0);

// Set resolution (1 = use all data; higher values downsample)
plot->setResolution(1);

Interactive Operations

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// Enable mouse interaction
plot->enableMouse(true);

// Mouse operations:
// - Left button drag: Rotate view
// - Middle button drag: Pan
// - Scroll wheel: Zoom

// Set scale ratio
plot->setScale(1.0, 1.0, 1.0);  // X, Y, Z scale ratio

// Set rotation angles
plot->setRotation(45, 30, 60);  // X, Y, Z axis rotation angles (degrees)

Color Mapping

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#include <qwt3d_colormap_color.h>

using namespace Qwt3D;

// Enable color legend
plot->showColorLegend(true);

// Set color mapping based on Z values using a core colormap preset
plot->setDataColor(new ColorMapColor(plot, "viridis"));

Theme System (v7.3.1+)

The Qwt3D::Qwt3DTheme class provides one-click switching of 3D plot visual styles, encapsulating all visual attributes including background color, mesh color, data colormap, axis colors, title styling, lighting presets, and shading modes.

Built-in Preset Themes

Preset Name Description
Default White background + jet colormap + no lighting
Dark Dark gray background + viridis + soft lighting
Scientific White background + jet + studio lighting
Warm Warm-toned background + hot colormap
Cool Cool-toned background + cool colormap
Matplotlib matplotlib style (viridis + soft lighting)
EarthTones Earth tones + autumn colormap
Ocean Ocean tones + winter colormap
HighContrast Black background with white lines for high contrast
Presentation Large fonts + thick lines, suitable for presentations

Usage Examples

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#include <qwt3d_theme.h>

// Method 1: Use preset theme (recommended)
plot->applyTheme(Qwt3D::Qwt3DTheme::Dark);

// Method 2: Apply theme by name
plot->applyTheme("Scientific");

// Method 3: Custom theme
Qwt3D::Qwt3DTheme theme(Qwt3D::Qwt3DTheme::Scientific);
theme.setDataColorPreset("plasma");  // Use one of 22 scientific colormap presets
theme.setShininess(20.0);
theme.setLightingPreset(Qwt3D::Qwt3DTheme::Studio);
theme.apply(plot);

Colormap Presets

Qwt3D::Qwt3DTheme provides 22 scientific visualization colormaps via the core module's QwtColorMapPreset:

  • Perceptually uniform: viridis, plasma, inferno, magma, cividis
  • Classic: jet, hot, cool, spring, summer, autumn, winter
  • Grayscale: gray, bone, copper
  • Rainbow: rainbow, hsv, turbo
  • Diverging: coolwarm, rdylbu, rdylgn, spectral
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// Switch colormap
theme.setDataColorPreset("viridis");

// View all available presets
QStringList presets = QwtColorMapPreset::availablePresets();

Lighting Presets

Preset Description
NoLighting No lighting, solid color rendering
FlatLight Uniform ambient light
Studio Classic three-point lighting
Outdoor Strong directional light + ambient
Soft Soft diffuse lighting

Build Configuration

To use 3D features, enable the QWT_CONFIG_QWTPLOT_3D CMake option:

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find_package(qwt REQUIRED)

# Link 2D plot library
target_link_libraries(${PROJECT_NAME} PRIVATE qwt::plot)

# Link 3D plot library
target_link_libraries(${PROJECT_NAME} PRIVATE qwt::plot3d)

OpenGL Dependency

The 3D plot module depends on OpenGL and GLU libraries. Ensure that OpenGL drivers and GLU library are installed on your system.

Core Method Summary

Method Class Description
setDomain() Qwt3D::Function / Qwt3D::GridMapping Set X/Y data range
setMesh() Qwt3D::Function / Qwt3D::GridMapping Set grid resolution (columns, rows)
setResolution() Qwt3D::SurfacePlot Set data resolution (1 = all data)
loadFromData() Qwt3D::SurfacePlot Load data array into the plot
create() Qwt3D::Function Generate and attach surface data
setRotation() Qwt3D::Plot3D Set rotation angles
setScale() Qwt3D::Plot3D Set scale ratio
enableMouse() Qwt3D::Plot3D Enable/disable mouse interaction
showColorLegend() Qwt3D::Plot3D Show/hide color legend
setDataColor() Qwt3D::Plot3D Set data color functor
updateData() Qwt3D::Plot3D Recalculate and update data

3D Plot Recommendations

  • Data size should not be too large (recommended under 100x100 grid)
  • For complex surfaces, reduce resolution to improve performance
  • Use lighting effects to enhance visual appearance

Related Examples

  • Basic 3D plot: examples/3D/simpleplot3D
  • 3D axis configuration: examples/3D/axes
  • 3D enrichments: examples/3D/enrichments
  • 3D auto switch: examples/3D/autoswitch
  • Dynamic 3D surface (QwtFigure integration): examples/3D/figureSurface3D

Screenshots of 3D axis configuration, 3D enrichments, 3D auto switch, and dynamic 3D surface:

3D Axes

3D Enrichments

3D Autoswitch

3D Figure Surface