OpenGL in QT QML, can't update my image on screen

Question

In order to use OpenGL with QML, I created OpenGlVideoQtQuick and OpenGlVideoQtQuickRenderer classes exactly as described here . The only difference is that I added the updateData() function to update the buffers, while in the example a static image is drawn in the screen.

Here's the crucial part of OpenGlVideoQtQuickRenderer , which is the paint function

void OpenGlVideoQtQuickRenderer::paint()
{
    if (this->firstRun) {
        this->firstRun = false;
        //qDebug() << "initializeGL";
        std::cout << "initializing gl" << std::endl;
        //初始化opengl （QOpenGLFunctions继承）函数
        initializeOpenGLFunctions();

        datas[0] = new unsigned char[width*height];     //Y
        datas[1] = new unsigned char[width*height/4];   //U
        datas[2] = new unsigned char[width*height/4];   //V   

        //this->m_F  = QOpenGLContext::currentContext()->functions();

        //program加载shader（顶点和片元）脚本
        //片元（像素）
        std::cout << program.addShaderFromSourceCode(QOpenGLShader::Fragment, tString2) << std::endl;
        //顶点shader
        std::cout << program.addShaderFromSourceCode(QOpenGLShader::Vertex, vString2) << std::endl;

        //设置顶点坐标的变量
        program.bindAttributeLocation("vertexIn",A_VER);

        //设置材质坐标
        program.bindAttributeLocation("textureIn",T_VER);

        //编译shader
        std::cout << "program.link() = " << program.link() << std::endl;

    }
    program.bind();

    //传递顶点和材质坐标
    //顶点
    static const GLfloat ver[] = {
        -1.0f,-1.0f,
        1.0f,-1.0f,
        -1.0f, 1.0f,
        1.0f,1.0f
    };

    //材质
    static const GLfloat tex[] = {
        0.0f, 1.0f,
        1.0f, 1.0f,
        0.0f, 0.0f,
        1.0f, 0.0f
    };

    //顶点
    glVertexAttribPointer(A_VER, 2, GL_FLOAT, 0, 0, ver);
    glEnableVertexAttribArray(A_VER);

    //材质
    glVertexAttribPointer(T_VER, 2, GL_FLOAT, 0, 0, tex);
    glEnableVertexAttribArray(T_VER);

    //glUseProgram(&program);
    //从shader获取材质
    unis[0] = program.uniformLocation("tex_y");
    unis[1] = program.uniformLocation("tex_u");
    unis[2] = program.uniformLocation("tex_v");

    //创建材质
    glGenTextures(3, texs);

    //Y
    glBindTexture(GL_TEXTURE_2D, texs[0]);
    //放大过滤，线性插值   GL_NEAREST(效率高，但马赛克严重)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    //创建材质显卡空间
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, width, height, 0, GL_RED, GL_UNSIGNED_BYTE, 0);

    //U
    glBindTexture(GL_TEXTURE_2D, texs[1]);
    //放大过滤，线性插值
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    //创建材质显卡空间
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, width/2, height / 2, 0, GL_RED, GL_UNSIGNED_BYTE, 0);

    //V
    glBindTexture(GL_TEXTURE_2D, texs[2]);
    //放大过滤，线性插值
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    //创建材质显卡空间
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, width / 2, height / 2, 0, GL_RED, GL_UNSIGNED_BYTE, 0);

    ///分配材质内存空间


    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texs[0]); //0层绑定到Y材质
    //修改材质内容(复制内存内容)
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RED, GL_UNSIGNED_BYTE, datas[0]);
    //与shader uni遍历关联
    glUniform1i(unis[0], 0);


    glActiveTexture(GL_TEXTURE0+1);
    glBindTexture(GL_TEXTURE_2D, texs[1]); //1层绑定到U材质
                                           //修改材质内容(复制内存内容)
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width/2, height / 2, GL_RED, GL_UNSIGNED_BYTE, datas[1]);
    //与shader uni遍历关联
    glUniform1i(unis[1],1);


    glActiveTexture(GL_TEXTURE0+2);
    glBindTexture(GL_TEXTURE_2D, texs[2]); //2层绑定到V材质
                                           //修改材质内容(复制内存内容)
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width / 2, height / 2, GL_RED, GL_UNSIGNED_BYTE, datas[2]);
    //与shader uni遍历关联
    glUniform1i(unis[2], 2);

    glDrawArrays(GL_TRIANGLE_STRIP,0,4);
    //this->update();

    // Not strictly needed for this example, but generally useful for when
    // mixing with raw OpenGL.
    m_window->resetOpenGLState();//COMMENT OR NOT?
}

This is the function I'm using to update the buffers that are meant to be painted:

void OpenGlVideoQtQuickRenderer::updateData(unsigned char**data)
{
    std::cout << "updating data..." << std::endl;
    memcpy(datas[0], data[0], width*height);
    memcpy(datas[1], data[1], width*height/4);
    memcpy(datas[2], data[2], width*height/4);
    //I should update something here

}

My only problem is that I see the function updateData being called with new data, so the buffers are being updated. However, the screen continues in its initial position (green). I'm sure there must be a function I must call to update everything.

Is there anything more I need to call in updateData ?

I tried every way of updating the data, but the image still won't update

            this->openGlVideoQtQuickRenderer->paint();
            if (this->openGlVideoQtQuick->window()) {
                std::cout << "window update" << std::endl;
                this->openGlVideoQtQuick->update();
                this->openGlVideoQtQuick->window()->update();
            }

However, if I resize the screen, I can see the image for less than a second and it disappears.

The entire code if someone wants to take a look: https://github.com/lucaszanella/orwell/blob/2aff3b97abd88e6ec2980856718e1c8302d41616/OpenGlVideoQtQuick.cpp#L117

Answer 1

Well, I tried to update the window as you see above, but the only thing that worked was

connect(window(), &QQuickWindow::afterRendering, this, &OpenGlVideoQtQuick::update, Qt::DirectConnection);

(and I had to take that update window from above off for this one to work)