结合OpenGl和QML时对glDrawArrays进行Segfault

我正在尝试编写一个应用程序，它通过OpenGL将纹理呈现为QML项目 . 在网上搜索并尝试各种各样的事情之后（感觉好像很多猜测，我对OpenGl的理解非常有限），我最终通过Valgrind运行程序并发现了一个非法的内存访问，这意味着我没有初始化所需的一切 . OpenGl正确绘制 . 我希望有人可以看看我粗略的代码并告诉我我忘了哪一步 .

我试着在QT文档中跟踪和组合这两个教程，这个教程展示了QML和OpenGl（http://doc.qt.io/qt-5/qtquick-scenegraph-openglunderqml-example.html），以及展示如何使用OpenGl和QT渲染纹理的这个（http://doc.qt.io/qt-5/qtopengl-textures-example.html） . 我稍微改了一下，因为我的纹理只是我希望显示的二维图像 . 我能够成功地跟随后者，将我的纹理渲染到视口并将其绘制在屏幕上，不幸的是，当尝试集成QML时，事情变得艰难 .

我的绘画功能如下：

void glViewer::paint()
    {
        // program is type QOpenGLShaderProgram *
        if (!program) initializeGL();
        if (!program->bind()) std::cerr << "Error: Program failed to bind\n";

        glViewport(0, 0, _viewportSize.width(), _viewportSize.height());
        glClearColor(clearColor.redF(), clearColor.greenF(), clearColor.blackF(), clearColor.alphaF());
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        QMatrix4x4 m;
        m.ortho(0.0f, 1.0f, 1.0f, 0.0f, 4.0f, 15.0f);
        m.translate(0.0f, 0.0f, -10.0f);
        program->setUniformValue("matrix", m);

        program->enableAttributeArray(PROGRAM_VERTEX_ATTRIBUTE);
        program->enableAttributeArray(PROGRAM_TEXCOORD_ATTRIBUTE);

        program->setAttributeBuffer(PROGRAM_VERTEX_ATTRIBUTE, GL_FLOAT, 0, 3, 5 * sizeof(GLfloat));
        program->setAttributeBuffer(PROGRAM_TEXCOORD_ATTRIBUTE, GL_FLOAT, 3 * sizeof(GLfloat), 2, 5 * sizeof(GLfloat));

        texture->bind();

        glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

        program->disableAttributeArray(PROGRAM_VERTEX_ATTRIBUTE);
        program->disableAttributeArray(PROGRAM_TEXCOORD_ATTRIBUTE);
        program->release();
        // _window refers the QQuickWindow generated by the QApplication
        _window->resetOpenGLState();
    }

如果没有着色器程序，第一行调用intializeGL（），这是我认为问题所在 . 该功能定义如下：

void glViewer::initializeGL()
    {
        initializeOpenGLFunctions();

        texture = new QOpenGLTexture(QOpenGLTexture::Target2D);
        texture->setSize(imageDisplayResolution.x,imageDisplayResolution.y,1);
        texture->setMinMagFilters(QOpenGLTexture::Nearest, QOpenGLTexture::Nearest);
        texture->setWrapMode(QOpenGLTexture::ClampToBorder);
        texture->setFormat(QOpenGLTexture::TextureFormat::R32F);
        texture->allocateStorage(QOpenGLTexture::Luminance, QOpenGLTexture::Float32);
        if (!texture->isStorageAllocated()) std::cerr << "Error: Failed to allocate texture!\n";

        QVector<GLfloat> vertData;

        // vertex position 
        vertData.append(0);
        vertData.append(0);
        vertData.append(0);
        // texture coordinate
        vertData.append(0);
        vertData.append(0);

        // vertex position 
        vertData.append(0);
        vertData.append(1);
        vertData.append(0);
        // texture coordinate
        vertData.append(0);
        vertData.append(1);

        // vertex position 
        vertData.append(1);
        vertData.append(1);
        vertData.append(0);
        // texture coordinate
        vertData.append(1);
        vertData.append(1);

        // vertex position 
        vertData.append(1);
        vertData.append(0);
        vertData.append(0);
        // texture coordinate
        vertData.append(1);
        vertData.append(0);

        vbo.create();
        if (!vbo.bind()) std::cerr << "Error: VBO bind has failed\n";
        vbo.allocate(vertData.constData(), vertData.count() * sizeof(GLfloat));

        // Enable or disable server-side GL capabilities.
        glEnable(GL_DEPTH_TEST);
        glEnable(GL_CULL_FACE);

    #define PROGRAM_VERTEX_ATTRIBUTE 0
    #define PROGRAM_TEXCOORD_ATTRIBUTE 1

        program = new QOpenGLShaderProgram;
        if (!program->addShaderFromSourceCode(QOpenGLShader::Vertex,
                                       "attribute highp vec4 vertex;\n"
                                        "attribute mediump vec4 texCoord;\n"
                                        "varying mediump vec4 texc;\n"
                                        "uniform mediump mat4 matrix;\n"
                                        "void main(void)\n"
                                        "{\n"
                                        "    gl_Position = matrix * vertex;\n"
                                        "    texc = texCoord;\n"
                                        "}\n")) { std::cerr << "Error: Vertex shader failed to compile!\n"; }
        if (!program->addShaderFromSourceCode(QOpenGLShader::Fragment,
                                       "uniform sampler2D texture;\n"
                                        "varying mediump vec4 texc;\n"
                                        "void main(void)\n"
                                        "{\n"
                                        "    gl_FragColor = texture2D(texture, texc.st).rrra;\n"
                                        "}\n")) { std::cerr << "Error: Fragment shader failed to compile!\n"; }
        // Binds the attribute name to the specified location.
        program->bindAttributeLocation("vertex", PROGRAM_VERTEX_ATTRIBUTE);
        program->bindAttributeLocation("texCoord", PROGRAM_TEXCOORD_ATTRIBUTE);

        if (!program->link()) std::cerr << "Error: Program shaders failed to link\n";
        if (!program->bind()) std::cerr << "Error: Program failed to bind\n";
        program->setUniformValue("texture", 0);
    }

paint（）是一个连接到QQuickWindow :: beforeRendering信号的插槽 . 使用调试器逐步调试告诉我，当调用paint（）时，所有指针（纹理，程序）都不为null . 没有OpenGL调用抛出错误，程序只是在glDrawArrays上的paint（）中段错误 .

谢谢！

编辑：进一步的调试告诉我它已成功通过绘画功能一次，它在第二次通过它失败 . 但是，我从未看到完全绘制的纹理，只填写了应用程序背景 .