如何在Qt OpenGL中使用PBO

我正在尝试使用QOpenGLBuffer作为像素缓冲区对象。目标是显示高分辨率视频流（4K，60FPS），因此我需要良好的性能。

由于我只是从OpenGL开始，因此我首先尝试以最佳方式显示简单的2D纹理。我已经包含了VBO和VAO，下一步（如我所读）将是使用PBO以获得更好的性能。

有针对PBO的教程，但使用glGenBufferARB（），而不使用QOpenGLBuffer。

这是我的代码：

glwidget.h

#ifndef GLWIDGET_H
#define GLWIDGET_H

#include <QOpenGLWidget>
#include <QOpenGLFunctions>
#include <QOpenGLBuffer>
#include <QDebug>
#include <QOpenGLTexture>
#include <QOpenGLShader>
#include <QOpenGLShaderProgram>
#include <QOpenGLVertexArrayObject>




class GLWidget : public QOpenGLWidget, protected QOpenGLFunctions
{
    Q_OBJECT
public:
    explicit GLWidget(QWidget *parent = 0);

    ~GLWidget();

    void initializeGL();
    void paintGL();
    void resizeGL(int w, int h);
    void LoadGLTextures();

private :

    QOpenGLShaderProgram *program;
    QOpenGLBuffer vbo;
    QOpenGLVertexArrayObject vao;
    GLuint tex;

    GLint vertexLocation;
    GLint texcoordLocation;

    int tailleVerticesBytes;
    int tailleCoordTexturesBytes;

    float vertices[8];
    float coordTexture[8];


public slots:



private slots:



};

#endif // GLWIDGET_H

glwidget.cpp

#ifndef BUFFER_OFFSET
#define BUFFER_OFFSET(offset) ((char*)NULL + (offset))

#include "glwidget.h"
#include <QElapsedTimer>


GLWidget::GLWidget(QWidget *parent) :
        QOpenGLWidget(parent)
{
    tailleVerticesBytes = 8*sizeof(float);
    tailleCoordTexturesBytes = 8*sizeof(float);
}

GLWidget::~GLWidget(){

    vao.destroy();
    vbo.destroy();
    delete program;
    glDeleteTextures(1, &tex);

}

void GLWidget::LoadGLTextures(){

    QImage img;

    if(!img.load("C:\\Users\\Adrien\\Desktop\\open3.bmp")){
        qDebug()<<"Image loading failed";
    }

    QImage t = (img.convertToFormat(QImage::Format_RGBA8888)).mirrored();

    glGenTextures(1, &tex);

    glBindTexture(GL_TEXTURE_2D, tex);

        glTexImage2D(GL_TEXTURE_2D, 0, 3, t.width(), t.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, t.bits());
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    glBindTexture( GL_TEXTURE_2D, 0);



}

void GLWidget::initializeGL(){


    float verticesTmp[] = {-1.0,-1.0,  1.0,-1.0,  1.0,1.0,  -1.0,1.0};
    float coordTextureTmp[] = {0.0,0.0,  1.0,0.0,  1.0,1.0,  0.0,1.0};

    for(int i = 0; i<8; i++){
        vertices[i] = verticesTmp[i];
        coordTexture[i] = coordTextureTmp[i];
    }

    initializeOpenGLFunctions();
    glClear(GL_COLOR_BUFFER_BIT);
    glEnable(GL_TEXTURE_2D);
    LoadGLTextures();

    //Shader setup
    QOpenGLShader *vshader = new QOpenGLShader(QOpenGLShader::Vertex, this);
    const char *vsrc =
        "#version 150 core\n"
        "in vec2 in_Vertex;\n"
        "in vec2 vertTexCoord;\n"
        "out vec2 fragTexCoord;\n"
        "void main(void)\n"
        "{\n"
        "    gl_Position = vec4(in_Vertex, 0.0, 1.0);\n"
        "    fragTexCoord = vertTexCoord;\n"
        "}\n";
    vshader->compileSourceCode(vsrc);

    QOpenGLShader *fshader = new QOpenGLShader(QOpenGLShader::Fragment, this);
    const char *fsrc =
            "#version 150 core\n"
            "uniform sampler2D tex;\n"
            "in vec2 fragTexCoord;\n"
            "void main(void)\n"
            "{\n"
            "    gl_FragColor = texture2D(tex,fragTexCoord);\n"
            "}\n";
    fshader->compileSourceCode(fsrc);

    program = new QOpenGLShaderProgram;
    program->addShader(vshader);
    program->addShader(fshader);
    program->link();
    program->bind();
    glActiveTexture(GL_TEXTURE0);
    program->setUniformValue("tex", 0);

    vertexLocation = glGetAttribLocation(program->programId(), "in_Vertex");
    texcoordLocation = glGetAttribLocation(program->programId(), "vertTexCoord");

    //VAO setup
    vao.create();
    vao.bind();

    //VBO setup
    vbo.create();
    vbo.setUsagePattern(QOpenGLBuffer::StaticDraw);
    vbo.bind();
    vbo.allocate(tailleVerticesBytes + tailleCoordTexturesBytes);
    vbo.write(0, vertices, tailleVerticesBytes);
    vbo.write(tailleVerticesBytes, coordTexture, tailleCoordTexturesBytes);

    program->enableAttributeArray(vertexLocation);
    program->setAttributeBuffer(vertexLocation, GL_FLOAT, 0, 2);
    program->enableAttributeArray(texcoordLocation);
    program->setAttributeBuffer(texcoordLocation, GL_FLOAT, tailleVerticesBytes, 2);

    vbo.release();
    vao.release();
    program->release();



}

void GLWidget::paintGL(){

    glClear(GL_COLOR_BUFFER_BIT);

    program->bind();
    {
        vao.bind();

            glBindTexture(GL_TEXTURE_2D, tex);

                glDrawArrays(GL_QUADS, 0, 4);

            glBindTexture(GL_TEXTURE_2D, 0);

        vao.release();
    }
    program->release();

}

void GLWidget::resizeGL(int w, int h){

    glViewport(0, 0, (GLint)w, (GLint)h);

}



#endif

因此，基本上，我将如何在此代码中使用PBO？

首先要做的是在指定类型（QOpenglBuffer :: PixelUnpackBuffer）的同时创建一个QOpenGLBuffer对象，然后我想我需要将像素上载到缓冲区中，最后使用它代替glTexImage2D吗？这只是全球性想法，我不知道如何去做。

谢谢。