QSurfaceFormat does not allow to draw with OpenGL

8Observer8

It works nice (I see a square) without QSurfaceFormat when I comment it:

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

//    QSurfaceFormat format;
//    format.setSamples(8);

    Widget w;
//    w.setFormat(format);
    w.show();
    return a.exec();
}

But when I uncomment it the code does not draw the square:

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QSurfaceFormat format;
//    format.setSamples(8);

    Widget w;
    w.setFormat(format);
    w.show();
    return a.exec();
}

main.cpp

// Add this line to .pro:
// win32: LIBS += -lopengl32

#ifdef _WIN32
#include <windows.h>
extern "C" __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
extern "C" __declspec(dllexport) DWORD AmdPowerXpressRequestHighPerformance = 0x00000001;
#endif

#include <QtWidgets/QApplication>
#include <QtWidgets/QOpenGLWidget>
#include <QtGui/QOpenGLShaderProgram>
#include <QtGui/QOpenGLBuffer>
#include <QtGui/QMatrix4x4>
#include <QtGui/QSurfaceFormat>

class Widget : public QOpenGLWidget
{
public:
    Widget()
    {
        setWindowTitle("Square. Qt, OpenGL 3.3, C++");
        setFixedSize(QSize(400, 400));
    }

private:
    QOpenGLShaderProgram m_program;
    QOpenGLBuffer m_vertPosBuffer;
    QOpenGLBuffer m_texCoordBuffer;
    QMatrix4x4 m_mvpMatrix;
    QMatrix4x4 m_projMatrix;
    QMatrix4x4 m_viewMatrix;
    QMatrix4x4 m_modelMatrix;
    int m_uMvpMatrixLocation;

    void initializeGL() override
    {
        glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
        const char *vertShaderSrc =
                "#version 330\n"
                "in vec3 aPosition;"
                "uniform mat4 uMvpMatrix;"
                "void main()"
                "{"
                "    gl_Position = uMvpMatrix * vec4(aPosition, 1.0);"
                "}";
        const char *fragShaderSrc =
                "#version 330\n"
                "out vec4 fragColor;"
                "void main()"
                "{"
                "    fragColor = vec4(0.9, 0.9, 1.0, 1.0);"
                "}";

        m_program.addShaderFromSourceCode(QOpenGLShader::Vertex, vertShaderSrc);
        m_program.addShaderFromSourceCode(QOpenGLShader::Fragment, fragShaderSrc);
        m_program.link();
        m_program.bind();

        float vertPositions[] = {
            -0.5f, -0.5f, 0.f,
            0.5f, -0.5f, 0.f,
            -0.5f, 0.5f, 0.f,
            0.5f, 0.5f, 0.f
        };
        m_vertPosBuffer.create();
        m_vertPosBuffer.bind();
        m_vertPosBuffer.allocate(vertPositions, sizeof(vertPositions));
        m_program.bindAttributeLocation("aPosition", 0);
        m_program.setAttributeBuffer(0, GL_FLOAT, 0, 3);
        m_program.enableAttributeArray(0);

        m_viewMatrix.lookAt(QVector3D(0.f, 0.f, 50.f),
                            QVector3D(0.f, 0.f, 0.f),
                            QVector3D(0.f, 1.f, 0.f));
        m_modelMatrix.scale(100.f, 100.f, 100.f);
    }

    void paintGL() override
    {
        glClear(GL_COLOR_BUFFER_BIT);
        m_mvpMatrix = m_projMatrix * m_viewMatrix * m_modelMatrix;
        m_program.bind();
        m_program.setUniformValue(m_uMvpMatrixLocation, m_mvpMatrix);
        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
    }

    void resizeGL(int w, int h) override
    {
        glViewport(0, 0, w, h);
        m_projMatrix.setToIdentity();
        m_projMatrix.ortho(-100.f, 100.f, -100.f, 100.f, 100.f, -100.f);
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QSurfaceFormat format;
//    format.setSamples(8);

    Widget w;
    w.setFormat(format);
    w.show();
    return a.exec();
}

8Observer8

I found my stupid mistake. I just forgot to get a uniform location for uMvpMatrix: m_uMvpMatrixLocation = m_program.uniformLocation("uMvpMatrix");

main.cpp

// Add this line to .pro:
// win32: LIBS += -lopengl32

#ifdef _WIN32
#include <windows.h>
extern "C" __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
extern "C" __declspec(dllexport) DWORD AmdPowerXpressRequestHighPerformance = 0x00000001;
#endif

#include <QtWidgets/QApplication>
#include <QtWidgets/QOpenGLWidget>
#include <QtGui/QOpenGLShaderProgram>
#include <QtGui/QOpenGLBuffer>
#include <QtGui/QMatrix4x4>
#include <QtGui/QSurfaceFormat>

class Widget : public QOpenGLWidget
{
    Q_OBJECT
public:
    Widget()
    {
        setWindowTitle("Rectangle. Qt, OpenGL 3.3, C++");
        setFixedSize(QSize(400, 400));
        resize(400, 400);
    }

private:
    QOpenGLShaderProgram m_program;
    QOpenGLBuffer m_vertPosBuffer;
    QOpenGLBuffer m_texCoordBuffer;
    QMatrix4x4 m_mvpMatrix;
    QMatrix4x4 m_projMatrix;
    QMatrix4x4 m_viewMatrix;
    QMatrix4x4 m_modelMatrix;
    int m_uMvpMatrixLocation;

    void initializeGL() override
    {
        glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
        glEnable(GL_DEPTH_TEST);
        const char *vertShaderSrc =
                "#version 330\n"
                "in vec3 aPosition;"
                "uniform mat4 uMvpMatrix;"
                "void main()"
                "{"
                "    gl_Position = uMvpMatrix * vec4(aPosition, 1.0);"
                "}";
        const char *fragShaderSrc =
                "#version 330\n"
                "out vec4 fragColor;"
                "void main()"
                "{"
                "    fragColor = vec4(0.9, 0.9, 1.0, 1.0);"
                "}";

        m_program.addShaderFromSourceCode(QOpenGLShader::Vertex, vertShaderSrc);
        m_program.addShaderFromSourceCode(QOpenGLShader::Fragment, fragShaderSrc);
        m_program.link();
        m_program.bind();

        m_uMvpMatrixLocation = m_program.uniformLocation("uMvpMatrix");

        float vertPositions[] = {
            -0.5f, -0.5f, 0.f,
            0.5f, -0.5f, 0.f,
            -0.5f, 0.5f, 0.f,
            0.5f, 0.5f, 0.f
        };
        m_vertPosBuffer.create();
        m_vertPosBuffer.bind();
        m_vertPosBuffer.allocate(vertPositions, sizeof(vertPositions));
        m_program.bindAttributeLocation("aPosition", 0);
        m_program.setAttributeBuffer(0, GL_FLOAT, 0, 3);
        m_program.enableAttributeArray(0);

        m_viewMatrix.lookAt(QVector3D(0.f, 0.f, 50.f),
                            QVector3D(0.f, 0.f, 0.f),
                            QVector3D(0.f, 1.f, 0.f));
        m_modelMatrix.translate(QVector3D(0.f, 0.f, 0.f));
        m_modelMatrix.rotate(20.f, QVector3D(0.f, 0.f, 1.f));
        m_modelMatrix.scale(50.f, 70.f, 1.f);
    }

    void paintGL() override
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        m_mvpMatrix = m_projMatrix * m_viewMatrix * m_modelMatrix;
        m_program.bind();
        m_program.setUniformValue(m_uMvpMatrixLocation, m_mvpMatrix);
        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
    }

    void resizeGL(int w, int h) override
    {
        glViewport(0, 0, w, h);
        m_projMatrix.setToIdentity();
        m_projMatrix.ortho(-100.f, 100.f, -100.f, 100.f, 100.f, -100.f);
    }
};

#include "main.moc"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QSurfaceFormat format;
    format.setSamples(8);

    Widget w;
    w.setFormat(format);
    QSurfaceFormat::setDefaultFormat(format);
    w.show();
    return a.exec();
}

SGaist

Hi,

What if you call QSurfaceFormat::setDefaultFormat(format) ?

8Observer8

@SGaist said in QSurfaceFormat does not allow to draw with OpenGL:

What if you call QSurfaceFormat::setDefaultFormat(format) ?

The same:

8Observer8

But I decided to make a new example from scratch (see a code below) with the same task (drawing a rectanle) with format.setSamples(8);. But I made the separated files (Widget.h/Widget.cpp, default.vert/default.frag). It works without that problem. I do not understand why it does not work in one file. I worked before.

main.cpp

// Add this line to .pro:
// win32: LIBS += -lopengl32

#ifdef _WIN32
#include <windows.h>
extern "C" __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
extern "C" __declspec(dllexport) DWORD AmdPowerXpressRequestHighPerformance = 0x00000001;
#endif

#include "Widget.h"

#include <QtGui/QSurfaceFormat>
#include <QtWidgets/QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QSurfaceFormat format;
    format.setSamples(8);
    Widget w;
    w.setFormat(format);
    w.show();
    return a.exec();
}

Widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QtGui/QOpenGLBuffer>
#include <QtGui/QOpenGLShaderProgram>
#include <QtWidgets/QOpenGLWidget>

class Widget : public QOpenGLWidget
{
    Q_OBJECT

public:
    Widget();
    ~Widget();

private:
    void initializeGL() override;
    void paintGL() override;
    void resizeGL(int w, int h) override;

    QOpenGLShaderProgram m_program;
    QOpenGLBuffer m_vertPosBuffer;
};

#endif // WIDGET_H

Widget.cpp

#include "Widget.h"

Widget::Widget()
{
    setWindowTitle("OpenGL 3.3, Qt5, C++");
    setFixedSize(QSize(450, 600));
}

Widget::~Widget()
{
}

void Widget::initializeGL()
{
    glClearColor(0.2f, 0.2f, 0.2f, 1.f);
    glEnable(GL_DEPTH_TEST);

    m_program.addCacheableShaderFromSourceFile(QOpenGLShader::Vertex, ":/Assets/Shaders/default.vert");
    m_program.addCacheableShaderFromSourceFile(QOpenGLShader::Fragment, ":/Assets/Shaders/default.frag");
    m_program.link();
    m_program.bind();

    float vertPositions[] = {
        -0.5f, -0.5f, 0.f,
        0.5f, -0.5f, 0.f,
        -0.5f, 0.5f, 0.f,
        0.5f, 0.5f, 0.f
    };
    m_vertPosBuffer.create();
    m_vertPosBuffer.bind();
    m_vertPosBuffer.allocate(vertPositions, sizeof(vertPositions));

    m_program.bindAttributeLocation("aPosition", 0);
    m_program.setAttributeBuffer(0, GL_FLOAT, 0, 3);
    m_program.enableAttributeArray(0);
}

void Widget::paintGL()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}

void Widget::resizeGL(int w, int h)
{
    glViewport(0, 0, w, h);
}

default.vert

#version 330

in vec3 aPosition;

void main()
{
    gl_Position = vec4(aPosition, 1.0);
}

default.frag

#version 330

out vec4 fragColor;

void main()
{
    fragColor = vec4(1.0, 1.0, 0.0, 1.0);
}

8Observer8

I found my stupid mistake. I just forgot to get a uniform location for uMvpMatrix: m_uMvpMatrixLocation = m_program.uniformLocation("uMvpMatrix");

main.cpp

// Add this line to .pro:
// win32: LIBS += -lopengl32

#ifdef _WIN32
#include <windows.h>
extern "C" __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
extern "C" __declspec(dllexport) DWORD AmdPowerXpressRequestHighPerformance = 0x00000001;
#endif

#include <QtWidgets/QApplication>
#include <QtWidgets/QOpenGLWidget>
#include <QtGui/QOpenGLShaderProgram>
#include <QtGui/QOpenGLBuffer>
#include <QtGui/QMatrix4x4>
#include <QtGui/QSurfaceFormat>

class Widget : public QOpenGLWidget
{
    Q_OBJECT
public:
    Widget()
    {
        setWindowTitle("Rectangle. Qt, OpenGL 3.3, C++");
        setFixedSize(QSize(400, 400));
        resize(400, 400);
    }

private:
    QOpenGLShaderProgram m_program;
    QOpenGLBuffer m_vertPosBuffer;
    QOpenGLBuffer m_texCoordBuffer;
    QMatrix4x4 m_mvpMatrix;
    QMatrix4x4 m_projMatrix;
    QMatrix4x4 m_viewMatrix;
    QMatrix4x4 m_modelMatrix;
    int m_uMvpMatrixLocation;

    void initializeGL() override
    {
        glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
        glEnable(GL_DEPTH_TEST);
        const char *vertShaderSrc =
                "#version 330\n"
                "in vec3 aPosition;"
                "uniform mat4 uMvpMatrix;"
                "void main()"
                "{"
                "    gl_Position = uMvpMatrix * vec4(aPosition, 1.0);"
                "}";
        const char *fragShaderSrc =
                "#version 330\n"
                "out vec4 fragColor;"
                "void main()"
                "{"
                "    fragColor = vec4(0.9, 0.9, 1.0, 1.0);"
                "}";

        m_program.addShaderFromSourceCode(QOpenGLShader::Vertex, vertShaderSrc);
        m_program.addShaderFromSourceCode(QOpenGLShader::Fragment, fragShaderSrc);
        m_program.link();
        m_program.bind();

        m_uMvpMatrixLocation = m_program.uniformLocation("uMvpMatrix");

        float vertPositions[] = {
            -0.5f, -0.5f, 0.f,
            0.5f, -0.5f, 0.f,
            -0.5f, 0.5f, 0.f,
            0.5f, 0.5f, 0.f
        };
        m_vertPosBuffer.create();
        m_vertPosBuffer.bind();
        m_vertPosBuffer.allocate(vertPositions, sizeof(vertPositions));
        m_program.bindAttributeLocation("aPosition", 0);
        m_program.setAttributeBuffer(0, GL_FLOAT, 0, 3);
        m_program.enableAttributeArray(0);

        m_viewMatrix.lookAt(QVector3D(0.f, 0.f, 50.f),
                            QVector3D(0.f, 0.f, 0.f),
                            QVector3D(0.f, 1.f, 0.f));
        m_modelMatrix.translate(QVector3D(0.f, 0.f, 0.f));
        m_modelMatrix.rotate(20.f, QVector3D(0.f, 0.f, 1.f));
        m_modelMatrix.scale(50.f, 70.f, 1.f);
    }

    void paintGL() override
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        m_mvpMatrix = m_projMatrix * m_viewMatrix * m_modelMatrix;
        m_program.bind();
        m_program.setUniformValue(m_uMvpMatrixLocation, m_mvpMatrix);
        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
    }

    void resizeGL(int w, int h) override
    {
        glViewport(0, 0, w, h);
        m_projMatrix.setToIdentity();
        m_projMatrix.ortho(-100.f, 100.f, -100.f, 100.f, 100.f, -100.f);
    }
};

#include "main.moc"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QSurfaceFormat format;
    format.setSamples(8);

    Widget w;
    w.setFormat(format);
    QSurfaceFormat::setDefaultFormat(format);
    w.show();
    return a.exec();
}