Managing / deleting multiple Qt3DVisualization / Q3DScatter in a window

Hi !
I have an issue deleting and replacing 3Dscatter and 3DSurface plots in Qt in C++. I'm working with QtDataVisualization in C++ and I've been stuck for half a year with the following problem : when I try to replace a Q3DScatter graph A by a Q3DScatter graph B, the deletion of graph A makes graph B unreadable if B is built before A is destroyed.

I'm trying to figure out at which point graph A and graph B interact with each other while they are not supposed to. I have a sample code here that is close to a MWE. I have let the function "build" in, but what it does is just initializing the graph and storing its address in a pointer, m3DGraph.

If PROBLEM is set to false, deletion step and creation of the next data are exchanged, and the issue does not happen, but it's not what I'm looking for since I want to update my display once the data is computed, and to be able to change the type of graph in the m3DImageHolder.

I think it's worth mentionning that I've done the test with a Q3DSurface graph and there is a similar issue : with Q3DScatter, the graph doesn't display, with Q3DSurface, the grid disappears.

I already posted this to StackOverflow, but did not get any answer. I link the question here in case there are further discussions Stack Overflow Question



Here is the header:

Code:

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#include <QDialog>
#include <QtWidgets/QLabel>
#include <QtWidgets/QVBoxLayout>
#include <QtDataVisualization/Q3DScatter>
#include <QtDataVisualization/Q3DSurface>
 
namespace QtD = QtDataVisualization;
 
class ViewerTest : public QDialog{
private:
    QPushButton *mHide,*mNewScat,*mNewSurf;
 
    QVBoxLayout *m3DLayoutHolder;
    QHBoxLayout *mButtonsLayout;
    QVBoxLayout *mMainLayout;
 
    QWidget *m3DImageHolder;
 
    QtD::Q3DScatter *m3DGraph;
    QtD::Q3DSurface *m3DGraphSurface;
public:
    enum TYPE{HIDE_BOTH,SCATTER,SURF};
 
    ViewerTest();
    void buildScatter(){manageGraphs(TYPE::SCATTER);};
    void buildSurface(){manageGraphs(TYPE::SURF);};
    void hideAll(){manageGraphs();};
    void build(TYPE type);
    void manageGraphs(TYPE type=HIDE_BOTH); //Shows or hide graphs
};

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Here is the .cpp

Code:

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#include "test3DvisuData.h"
 
#include <QPushButton>
#include <iostream>
#include <QtDataVisualization/qcustom3dlabel.h>
#include <QtDataVisualization/q3dscatter.h>
#include <QtDataVisualization/q3dsurface.h>
#include <QtDataVisualization/QCustom3DVolume>
#include <QtDataVisualization/Q3DInputHandler>
#include <QtDataVisualization/QHeightMapSurfaceDataProxy>
#include <QApplication>
 
#define PROBLEM true
/// Short class for debugging objects creation
template<typename T> class GraphTest: public T{
    const int mLabel;
    static int label;
    std::string name;
public:
    GraphTest(const std::string & in):T(),mLabel(label++),name(in){
        std::cout<<" ctor "<< name <<mLabel<< std::endl;
    };
    ~GraphTest(){
        std::cout<<" ~dtor "<< name << mLabel<<std::endl;
    };
};
 
template <typename T>int GraphTest<T>::label = 0;
 
 
ViewerTest::ViewerTest():m3DImageHolder(nullptr),m3DGraph(nullptr),m3DGraphSurface(nullptr){
    mHide = new QPushButton("hide",this);
    mNewScat = new QPushButton("scat",this);
    mNewSurf = new QPushButton("surf",this);
 
    m3DLayoutHolder = new QVBoxLayout();
    mButtonsLayout = new QHBoxLayout();
    mMainLayout = new QVBoxLayout(this);
    setLayout(mMainLayout);
    mMainLayout->addLayout(mButtonsLayout);
    mMainLayout->addLayout(m3DLayoutHolder);
 
    mButtonsLayout->addWidget(mHide);
    mButtonsLayout->addWidget(mNewScat);
    mButtonsLayout->addWidget(mNewSurf);
 
    connect(mNewSurf,&QPushButton::released,this,&ViewerTest::buildSurface);
    connect(mNewScat,&QPushButton::released,this,&ViewerTest::buildScatter);
    connect(mHide,&QPushButton::released,this,&ViewerTest::hideAll);
 
}
 
///This part is just the data construction
 
void ViewerTest::build(TYPE type) {
    if(type==SCATTER) {
        m3DGraph = new /*QtD::Q3DScatter();*/GraphTest<QtD::Q3DScatter>("inData3D");
        m3DGraph->scene()->activeCamera()->setCameraPreset( QtD::Q3DCamera::CameraPresetIsometricRight );
        m3DGraph->setOrthoProjection(true);
        QtD::QCustom3DVolume *vol = new QtD::QCustom3DVolume;
        vol->setScaling(
                    QVector3D(m3DGraph->axisX()->max() - m3DGraph->axisX()->min(),
                             (m3DGraph->axisY()->max() - m3DGraph->axisY()->min()) * 1.0f,
                             m3DGraph->axisZ()->max() - m3DGraph->axisZ()->min()));
        vol->setScalingAbsolute(false);
 
        // Build the data
        unsigned int height(20),width(20),depth(20);
        QVector<uchar> *vectorData = new QVector<uchar>(height * width * depth * 4, 0);
        vol->setTextureWidth(width);vol->setTextureHeight(height);vol->setTextureDepth(depth);
 
        vol->setTextureFormat(QImage::Format_ARGB32);
        for (int z = 0; z < height; z++) {
            for (int y = 0; y < depth; y++) {
                for (int x = 0; x < width; x++) {
                    for( int c = 0; c<4; c++){
                        (*vectorData)[(x + width * z + width * height * y) * 4 + c] = 
                            c==0?x*5:(c==1?y*5:(c==2?z*5:20));
                    }
                }
            }
        }
        vol->setTextureData(vectorData);
        m3DGraph->addCustomItem(vol);
    }
 
    ///// ------------------
    else if(type==SURF){
        QImage image = QImage(20,20,QImage::Format_Grayscale8);
        for(uint x=0; x<20; x++){
            for(uint y=0; y<20; y++){
                image.setPixelColor(x,y,QColor(x*y));
            }
        }
        QtD::QHeightMapSurfaceDataProxy *proxy = new QtD::QHeightMapSurfaceDataProxy(image);
        QtD::QSurface3DSeries *serie = new QtD::QSurface3DSeries(proxy);
        serie->setDrawMode(QtD::QSurface3DSeries::DrawSurface);
 
        m3DGraphSurface = new GraphTest<QtD::Q3DSurface>("inData3DSurface");
        m3DGraphSurface->addSeries(serie);
        m3DGraphSurface->seriesList().at(0)->setColorStyle( QtD::Q3DTheme::ColorStyleRangeGradient );
 
    }
 
}

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and here is the problematic function

Code:

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void ViewerTest::manageGraphs(TYPE type) {
#if PROBLEM
    build(type); //---> no error thrown, but graph don't display
#endif
 
    // delete previous
    m3DLayoutHolder->removeWidget(m3DImageHolder);
    delete m3DImageHolder;
    m3DImageHolder= nullptr;
 
#if PROBLEM
#else
    build(type); ///---> display works perfectly
#endif
 
    if(type == SCATTER) {
        m3DImageHolder = QWidget::createWindowContainer(m3DGraph, this);
    } else if(type==SURF){
        m3DImageHolder = QWidget::createWindowContainer(m3DGraphSurface,this);
    }
    if(type != TYPE::HIDE_BOTH) {
        m3DLayoutHolder->addWidget(m3DImageHolder);
        m3DImageHolder->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    }
 
}
 
// Just a Widget with two buttons (hide/new)
// OnClick, load a new3D dataset
 
int main(int argc, char** argv){
    QApplication qApplication( argc,  argv);
 
    ViewerTest viewerTest;
    return viewerTest.exec();
}

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