Q3DSurfaceWidgetItem 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 Q3DSurfaceWidgetItem supports selection by showing a highlighted ball on the data point where the user has clicked with the left mouse button (when the default input handler is in use) or selected via QSurface3DSeries. The selection pointer is accompanied by a label, which in the 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 the mouse wheel. Both actions assume the default input handler is in use.

If no axes are set explicitly for Q3DSurfaceWidgetItem, temporary default axes with no labels are created. These default axes can be modified via axis accessors, but as soon as any axis is set explicitly for the orientation, the default axis for that orientation is destroyed.

How to construct a minimal Q3DSurfaceWidgetItem graph

First, construct Q3DSurfaceWidgetItem. Since we are running the graph as a top-level window in this example, we need to clear the Qt::FramelessWindowHint flag, which is set by default:

 QQuickWidget quickWidget;
 Q3DSurfaceWidgetItem surface;
 surface.setWidget(&quickWidget);
 surface.widget()->setMinimumSize(QSize(256, 256));

Now Q3DSurfaceWidgetItem is ready to receive data to be rendered. Create data elements to receive values:

 QSurfaceDataArray data;
 QSurfaceDataRow dataRow1;
 QSurfaceDataRow dataRow2;

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

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

Create a new series and set data to it:

 QSurface3DSeries series;
 series.dataProxy()->resetArray(data);
 surface.addSeries(&series);

Finally you will need to set it visible:

 surface.widget()->show();

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

 #include <QtGraphs>
 #include <QtGraphsWidgets/q3dsurfacewidgetitem.h>
 #include <QtWidgets/qapplication.h>

 int main(int argc, char **argv)
 {
     QApplication app(argc, argv);

     QQuickWidget quickWidget;
     Q3DSurfaceWidgetItem surface;
     surface.setWidget(&quickWidget);
     surface.widget()->setMinimumSize(QSize(256, 256));
     QSurfaceDataArray data;
     QSurfaceDataRow dataRow1;
     QSurfaceDataRow dataRow2;

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

     QSurface3DSeries series;
     series.dataProxy()->resetArray(data);
     surface.addSeries(&series);
     surface.widget()->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 interactions are included in this minimal code example. You can learn more by familiarizing yourself with the examples provided, like the Surface Graph Gallery.