Draw texture in QQuickPaintedItem

[Dmitry89]

@#ifndef GLITEM_H
#define GLITEM_H

#include <QOpenGLFunctions>
#include <QQuickPaintedItem>
#include <QtOpenGL>

class GLItem : public QQuickPaintedItem, protected QOpenGLFunctions
{
Q_OBJECT
private:

GLuint texID[1];

public:
explicit GLItem(QQuickItem *parent = 0);

void paint(QPainter *painter);
bool init();

private:
int m_prog;
};

#endif // GLITEM_H
@

@
#include "glitem.h"
#include <QPainter>
#include <QtGui/QOpenGLShaderProgram>
#include <QtGui/QOpenGLContext>
#include <QDebug>

GLItem::GLItem(QQuickItem *parent)
: QQuickPaintedItem(parent)
, m_prog(0)
{
setRenderTarget(QQuickPaintedItem::InvertedYFramebufferObject);
}
bool GLItem::init()
{
glGenTextures(1,texID);
initializeOpenGLFunctions();
qDebug() << "init";
}

void GLItem::paint(QPainter *painter)
{
painter->beginNativePainting();

glClearColor(0.5f,0.0f,1.0f,255);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

float data[256*256*3];
for(int i = 0; i != 256*256*3; i++) {
    data[i] = (rand() % 1000)/1000.0f;
}

glActiveTexture(GL_TEXTURE0+0);
glBindTexture(GL_TEXTURE_2D, texID[0]);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, 256, 256, 0, GL_RGB, GL_FLOAT, data);

glEnable(GL_TEXTURE_2D);

float vTextureCoord[4][2];
vTextureCoord[0][0] = 0.0f;    vTextureCoord[0][1] = 0.0f;
vTextureCoord[1][0] = 1.0f;    vTextureCoord[1][1] = 0.0f;
vTextureCoord[2][0] = 0.0f;    vTextureCoord[2][1] = 1.0f;
vTextureCoord[3][0] = 1.0f;    vTextureCoord[3][1] = 1.0f;

float vVertexCoord[4][2];
vVertexCoord[0][0] = 0.0f;    vVertexCoord[0][1] = 0.0f;
vVertexCoord[1][0] = 600.0f;    vVertexCoord[1][1] = 0.0f;
vVertexCoord[2][0] = 0.0f;    vVertexCoord[2][1] = 600.0f;
vVertexCoord[3][0] = 600.0f;    vVertexCoord[3][1] = 600.0f;

glTexCoordPointer(2, GL_FLOAT, 0, vTextureCoord);
glVertexPointer(2, GL_FLOAT, 0, vVertexCoord);

glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisable(GL_TEXTURE_2D);

}
@

The program crashes with error:
ASSERT: "QOpenGLFunctions::isInitialized(d_ptr)"
Also functions glDrawArrays, makeCurrent(), glActiveTexture(...) don't want to work, function init() never calls and I can't initialize function initializeGL(...)
what I'm doing wrong, this code works fine with QGLWidget..

[sierdzio]

Why use QPainter? QtQuick already has helper methods for drawing textures, no need to dive into QPainter and OpenGL code. You can see an example here: "link":https://github.com/sierdzio/closecombatfree/blob/master/src/qmlBase/ccfqmlbasemap.cpp#L66.