[Qt] QOpenGLWidget override initializeGL and paintGL

[max]

> Really don't know :) Never played with OpenGL. Try to instantiate 
> QApplication, create QWindow and via it's QSurfaceType set to OpenGL 
> .. and see what happens :)
>
> zeljko
>
For OpenGL  we need "QOpenGLContext" only ;)

All function glXX are from "GL/gl.h"

Sample application in QT

////////////////////////////////////////////////////////////

//////////////// main.cpp

#include<QApplication>

#include<QWindow >

#include<QOpenGLContext >

//#include <QOpenGLFunctions>

#include<GL/gl.h >//

intmain(intargc,char*argv[])

{

QApplicationa(argc,argv);

QWindow*embed;

embed=newQWindow;

embed->setSurfaceType(QWindow::OpenGLSurface);

embed->setGeometry(QRect(50,50,640,480));

embed->setVisible(true);

QOpenGLContext*m_context;

m_context=newQOpenGLContext();

m_context->create();

m_context->makeCurrent(embed);

// <QOpenGLFunctions> version

//QOpenGLFunctions *f = m_context->functions();

//f->glClearColor(1.0,0,0,1.0);

//f->glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// <GL/gl.h> VERSION

glClearColor(1.0,0,0,1.0);

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

// Define shapes enclosed within a pair of glBegin and glEnd

glBegin(GL_QUADS);// Each set of 4 vertices form a quad

glColor3f(1.0f,0.0f,0.0f);// Red

glVertex2f(-0.8f,0.1f);// Define vertices in counter-clockwise (CCW) order

glVertex2f(-0.2f,0.1f);//  so that the normal (front-face) is facing you

glVertex2f(-0.2f,0.7f);

glVertex2f(-0.8f,0.7f);

glColor3f(0.0f,1.0f,0.0f);// Green

glVertex2f(-0.7f,-0.6f);

glVertex2f(-0.1f,-0.6f);

glVertex2f(-0.1f,0.0f);

glVertex2f(-0.7f,0.0f);

glColor3f(0.2f,0.2f,0.2f);// Dark Gray

glVertex2f(-0.9f,-0.7f);

glColor3f(1.0f,1.0f,1.0f);// White

glVertex2f(-0.5f,-0.7f);

glColor3f(0.2f,0.2f,0.2f);// Dark Gray

glVertex2f(-0.5f,-0.3f);

glColor3f(1.0f,1.0f,1.0f);// White

glVertex2f(-0.9f,-0.3f);

glEnd();

m_context->swapBuffers(embed);

returna.exec();

}

//////////////////////////////////////////////////////////// 
#-------------------------------------------------
#
#ProjectcreatedbyQtCreator2017-05-26T18:32:13
#
#-------------------------------------------------
QT+=coregui
LIBS+=-lglut-lopengl32
greaterThan(QT_MAJOR_VERSION,4):QT+=widgets
TARGET=nienazwany1
TEMPLATE=app
SOURCES+=main.cpp

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