How to render in Qt3D in standard GUI application? - c++

Question

I enjoy using Qt3D, but all of the examples I see for it are full window applications. What I can't understand from the examples is how to add a qt3d rendering window to a regular qt gui application.
Basically what I want is a little rendering widget for my Qt5 Gui application.
I've looked into Qtgl widget, but I really want to use the scene management abilities of Qt3D.
How can I render as a sub window inside of a qt Gui window?
Is this possible?
Update
So I added this to my MainWindow.cpp It is loosely based off of this https://www.qt.io/blog/2013/02/19/introducing-qwidgetcreatewindowcontainer
LoadModelView *view = new LoadModelView(); //Crashes on this. Will not compile with
// LoadModelView(this)
QWidget *container = QWidget::createWindowContainer(view);
container->setFocusPolicy(Qt::TabFocus);
ui->gridLayout->addWidget(container);
which seems right.
my load_model.cpp begins like this:
#include "qglmaterialcollection.h"
#include "qglmaterial.h"
#include "qglscenenode.h"
#include "qgllightmodel.h"
#include "qglabstractscene.h"
#include <QtGui/qmatrix4x4.h>
#include <QPropertyAnimation>
#include <QtCore/qmath.h>
#define DEGREE_TO_RAD (3.1415926/180.0)
LoadModelView::LoadModelView(QWindow *parent)
: QGLView(parent)
, m_pSTLScene(0)
{
loadModels();
camera()->setCenter(QVector3D(0, 0, 0));
camera()->setEye(QVector3D(0, 4, 10));
}
LoadModelView::~LoadModelView()
{
delete m_pSTLScene;
}
void LoadModelView::paintGL(QGLPainter *painter)
{
QMatrix4x4 stlWorld;
stlWorld.setToIdentity();
stlWorld.scale(0.1);
stlWorld.translate(QVector3D(2.0,0.0,0.0));
painter->setStandardEffect(QGL::LitMaterial);
painter->setFaceColor(QGL::AllFaces,QColor(170,202,0));
painter->modelViewMatrix() = camera()->modelViewMatrix() * stlWorld;
m_pSTLScene->mainNode()->draw(painter);
}
void FixNodesRecursive(int matIndex, QGLSceneNode* pNode)
{
if (pNode) {
pNode->setMaterialIndex(matIndex);
// pNode->setEffect(QGL::FlatReplaceTexture2D);
foreach (QGLSceneNode* pCh, pNode->children()) {
FixNodesRecursive(matIndex, pCh);
}
}
}
void LoadModelView::loadModels()
{
{
m_pSTLScene = QGLAbstractScene::loadScene(QLatin1String(":/models/Sheep.stl"), QString(),"CorrectNormals CorrectAcute");
Q_ASSERT(m_pSTLScene!=0);
QGLMaterial *mat = new QGLMaterial;
mat->setAmbientColor(QColor(170,202,0));
mat->setDiffuseColor(QColor(170,202,0));
mat->setShininess(128);
QGLSceneNode* pSTLSceneRoot = m_pSTLScene->mainNode();
int matIndex = pSTLSceneRoot->palette()->addMaterial(mat);
pSTLSceneRoot->setMaterialIndex(matIndex);
pSTLSceneRoot->setEffect(QGL::FlatReplaceTexture2D);
FixNodesRecursive(matIndex,pSTLSceneRoot);
}
}
It crashes with:
This application has requested the runtime to terminate it in an unusual way.
And in the qt application output:
Invalid parameter passed to C runtime function.
EDIT Added the rest of the class in question
I notice that in the example I am adapting https://github.com/Distrotech/qt3d/blob/master/tutorials/qt3d/penguin/main.cpp the window is initialized by saying:
LoadModelView view;
However, saying
LoadModelView *view = new LoadModelView(this)
crashes

Answer 1

You can subclass QGLView class which extends QGLWidget with support for 3D viewing:
class GLView : public QGLView
{
Q_OBJECT
public:
GLView(QWidget *parent = 0);
~GLView();
protected:
void initializeGL(QGLPainter *painter);
void paintGL(QGLPainter *painter);
private:
QGLAbstractScene *m_scene;
QGLSceneNode *m_rootNode;
};
GLView::GLView(QWidget *parent)
: QGLView(parent)
, m_scene(0)
, m_rootNode(0)
{
// Viewing Volume
camera()->setFieldOfView(25);
camera()->setNearPlane(1);
camera()->setFarPlane(1000);
// Position of the camera
camera()->setEye(QVector3D(0, 3, 4));
// Direction that the camera is pointing
camera()->setCenter(QVector3D(0, 3, 0));
}
GLView::~GLView()
{
delete m_scene;
}
void GLView::initializeGL(QGLPainter *painter)
{
// Background color
painter->setClearColor(QColor(70, 70, 70));
// Load the 3d model from the file
m_scene = QGLAbstractScene::loadScene("models/model1/simplemodel.obj");
m_rootNode = m_scene->mainNode();
}
void GLView::paintGL(QGLPainter *painter)
{
m_rootNode->draw(painter);
}
Qt 5.1 introduces the function QWidget::createWindowContainer(). A function that creates a QWidget wrapper for an existing QWindow, allowing it to live inside a QWidget-based application. You can use QWidget::createWindowContainer which creates a QWindow in a QWidget. This allows placing QWindow-subclasses in Widget-Layouts. This way you
can embed your QGLView inside a widget.

Answer 2

This is how I did it on Qt5.10. This example shows a scene with a cuboid. Scene you can than use like a button or so... To use this add QT += 3dextras to your project file.
szene.h
#ifndef SCENE_H
#define SCENE_H
#include <QObject>
#include <QWidget>
class Scene
: public QWidget
{
Q_OBJECT
private:
QWidget *container;
public:
explicit Scene(QWidget *parent = nullptr);
protected:
// reimplementation needed to handle resize events
// http://doc.qt.io/qt-5/qwidget.html#resizeEvent
void
resizeEvent ( QResizeEvent * event );
public slots:
void
resizeView(QSize size);
};
#endif // SCENE_H
scene.cpp
#include "scene.h"
#include <Qt3DExtras/Qt3DWindow>
#include <Qt3DExtras/QForwardRenderer>
#include <QQuaternion>
#include <Qt3DCore/QEntity>
#include <Qt3DCore/QTransform>
#include <Qt3DRender/QCamera>
#include <Qt3DExtras/QCuboidMesh>
#include <Qt3DExtras/QPhongMaterial>
Scene::Scene(QWidget *parent)
: QWidget(parent)
{
auto view = new Qt3DExtras::Qt3DWindow();
// create a container for Qt3DWindow
container = createWindowContainer(view,this);
// background color
view->defaultFrameGraph()->setClearColor(QColor(QRgb(0x575757)));
// Root entity
auto rootEntity = new Qt3DCore::QEntity();
// Camera
auto camera = new Camera(rootEntity,view);
auto cameraEntity = view->camera();
cameraEntity->setPosition(QVector3D(0, 0, 50.0f));
cameraEntity->setUpVector(QVector3D(0, 1, 0));
cameraEntity->setViewCenter(QVector3D(0, 0, 0));
// Cuboid
auto cuboidMesh = new Qt3DExtras::QCuboidMesh();
// CuboidMesh Transform
auto cuboidTransform = new Qt3DCore::QTransform();
cuboidTransform->setScale(10.0f);
cuboidTransform->setTranslation(QVector3D(0.0f, 0.0f, 0.0f));
cuboidTransform->setRotation(QQuaternion(1,1.5,1,0).normalized());
auto cuboidMaterial = new Qt3DExtras::QPhongMaterial();
cuboidMaterial->setDiffuse(QColor(QRgb(0x005FFF)));
// assamble entity
auto cuboidEntity = new Qt3DCore::QEntity(rootEntity);
cuboidEntity->addComponent(cuboidMesh);
cuboidEntity->addComponent(cuboidMaterial);
cuboidEntity->addComponent(cuboidTransform);
// Set root object of the scene
view->setRootEntity(rootEntity);
}
void
Scene::resizeView(QSize size)
{
container->resize(size);
}
void
Scene::resizeEvent ( QResizeEvent * /*event*/ )
{
resizeView(this->size());
}