QT 5 mixed opengl and qml problem

[matteli]

Hi all,

i want to mix opengl and QML stuff. I used qt 5 beta 2.
I make a minimalist programm for show you the problem :

main.ccp
@
#include <QGuiApplication>
#include "back.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Back b;
b.setSource(QUrl("ui.qml"));
b.show();

return a.exec();

}
@

back.h

@
#ifndef BACK_H
#define BACK_H
#include <QtQuick>
#include <QtOpenGL>
#include <QTimer>

class Back : public QQuickView
{
Q_OBJECT
public:
~Back();
Back();
public slots :
void paint();
};

#endif // BACK_H
@

back.ccp

@#include "back.h"

Back::Back()
{
setClearBeforeRendering(false);
connect(this, SIGNAL(beforeRendering()), this, SLOT(paint()), Qt::DirectConnection);
QTimer *timer = new QTimer(this);
connect(timer, SIGNAL(timeout()), this, SLOT(update()), Qt::DirectConnection);
timer->start(3000);
}

Back::~Back()
{
}

void Back::paint()
{
glViewport(0, 0, 150, 150);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 150, 150,0,0,10);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
glColor3ub(255, 0, 0);
glBegin(GL_QUADS);
    glVertex2i(0, 0);
    glVertex2i(100, 0);
    glVertex2i(100, 100);
    glVertex2i(0, 100);
glEnd();

}
@

ui.qml

@
import QtQuick 2.0

Item {
width : 150
height : 150

Rectangle {
     x : 50
     y : 50
     width: 100
     height: 100
     color: "green"
}

}
@

The first picture is correct :
I have a red square with a green square with offset and a black background.
"Picture 1":http://imageshack.us/photo/my-images/854/14898400.png

After 3 seconds, the second is uncorrect :
I have only the green square with withe background
"Picture 2":http://imageshack.us/photo/my-images/690/56801100.png

Is someone know what i make wrong ?

Thank you

matteli

[matteli]

Ok i inspect the problem and change a little my program.
My new minimalist program.

main.ccp
@#include <QGuiApplication>
#include "back.h"

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Back b;
b.setSource(QUrl("ui.qml"));
b.show();

return a.exec();

}
@

back.h
@#ifndef BACK_H
#define BACK_H
#include <QtQuick>
#include <QtOpenGL>
#include <QTimer>
#include <QColor>

class Back : public QQuickView
{
Q_OBJECT
public:
~Back();
Back();
public slots :
void paint();
private :
bool mColor;
};

#endif // BACK_H
@

back.ccp
@
#include "back.h"

Back::Back()
{
setClearBeforeRendering(false);
connect(this, SIGNAL(beforeRendering()), this, SLOT(paint()), Qt::DirectConnection);
QTimer *timer = new QTimer(this);
connect(timer, SIGNAL(timeout()), this, SLOT(update()), Qt::DirectConnection);
timer->start(1000);
mColor = true;
}

Back::~Back()
{
}

void Back::paint()
{
glViewport(0, 0, 300, 300);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0f, 300.0f, 300.0f,0.0f,0.0f,1.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

glDisable(GL_DEPTH_TEST);

glClearColor(0.0f, 1.0f, 1.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);


mColor=!mColor;
if (mColor) glColor4f(1.0f, 0.0f, 0.0f, 1.0f);
else glColor4f(1.0f, 1.0f, 0.0f,1.0f);
glBegin(GL_QUADS);
    glVertex2f(100.0f, 100.0f);
    glVertex2f(200.0f, 100.0f);
    glVertex2f(200.0f, 200.0f);
    glVertex2f(100.0f, 200.0f);
glEnd();

}
@

ui.qml
@
import QtQuick 2.0

Item {
width : 300
height : 300

Rectangle {
     x : 0
     y : 0
     width: 50
     height: 50
     color: "purple"
}

}
@

The result is good for the 1st picture
"Picture 1":http://imageshack.us/photo/my-images/694/picture11psi.png/

After 1 second, the 2nd picture is not good (black square)
"Picture 2":http://imageshack.us/photo/my-images/72/picture12mr.png/

Now i change only the qml file (x and y) :
@
import QtQuick 2.0

Item {
width : 300
height : 300

Rectangle {
     x : 50
     y : 50
     width: 50
     height: 50
     color: "purple"
}

}
@

1st picture good
"picture 1":http://imageshack.us/photo/my-images/571/picture21t.png/

2nd picture bad : square in black and with an offset.
"picture 2":http://imageshack.us/photo/my-images/820/picture22dh.png/

Do you think it's a bug af QT 5 ?

[matteli]

In my example, i mixed old rendering opengl stuff with qquick item which used VBO i presume. I think, it's not a good idea to mixed that. So now i used VBO for my rendering and it's work.