Q3DSurface Class

Detailed Description

This class enables developers to render 3D surface plots and to view them by rotating the scene freely. The visual properties of the surface such as draw mode and shading can be controlled via QSurface3DSeries.

The Q3DSurface supports selection by showing a highlighted ball on the data point where the user has clicked with left mouse button (when default input handler is in use) or selected via QSurface3DSeries. The selection pointer is accompanied with a label which in default case shows the value of the data point and the coordinates of the point.

The value range and the label format shown on the axis can be controlled through QValue3DAxis.

To rotate the graph, hold down the right mouse button and move the mouse. Zooming is done using mouse wheel. Both assume the default input handler is in use.

If no axes are set explicitly to Q3DSurface, temporary default axes with no labels are created. These default axes can be modified via axis accessors, but as soon any axis is set explicitly for the orientation, the default axis for that orientation is destroyed.

How to construct a minimal Q3DSurface graph

First, construct Q3DSurface. Since we are running the graph as top level window in this example, we need to clear the Qt::FramelessWindowHint flag, which gets set by default:

Q3DSurface surface;
surface.setFlags(surface.flags() ^ Qt::FramelessWindowHint);

Now Q3DSurface is ready to receive data to be rendered. Create data elements to receive values:

QSurfaceDataArray *data = new QSurfaceDataArray;
QSurfaceDataRow *dataRow1 = new QSurfaceDataRow;
QSurfaceDataRow *dataRow2 = new QSurfaceDataRow;

First feed the data to the row elements and then add their pointers to the data element:

*dataRow1 << QVector3D(0.0f, 0.1f, 0.5f) << QVector3D(1.0f, 0.5f, 0.5f);
*dataRow2 << QVector3D(0.0f, 1.8f, 1.0f) << QVector3D(1.0f, 1.2f, 1.0f);
*data << dataRow1 << dataRow2;

Create a new series and set data to it:

QSurface3DSeries *series = new QSurface3DSeries;
series->dataProxy()->resetArray(data);
surface.addSeries(series);

Finally you will need to set it visible:

surface.show();

The complete code needed to create and display this graph is:

#include <QtDataVisualization>

int main(int argc, char **argv)
{
    qputenv("QSG_RHI_BACKEND", "opengl");
    QGuiApplication app(argc, argv);

    Q3DSurface surface;
    surface.setFlags(surface.flags() ^ Qt::FramelessWindowHint);
    QSurfaceDataArray *data = new QSurfaceDataArray;
    QSurfaceDataRow *dataRow1 = new QSurfaceDataRow;
    QSurfaceDataRow *dataRow2 = new QSurfaceDataRow;

    *dataRow1 << QVector3D(0.0f, 0.1f, 0.5f) << QVector3D(1.0f, 0.5f, 0.5f);
    *dataRow2 << QVector3D(0.0f, 1.8f, 1.0f) << QVector3D(1.0f, 1.2f, 1.0f);
    *data << dataRow1 << dataRow2;

    QSurface3DSeries *series = new QSurface3DSeries;
    series->dataProxy()->resetArray(data);
    surface.addSeries(series);
    surface.show();

    return app.exec();
}

And this is what those few lines of code produce:

The scene can be rotated, zoomed into, and a surface point can be selected to view its position, but no other interaction is included in this minimal code example. You can learn more by familiarizing yourself with the examples provided, like the Surface Example.