Question

我最终试图在OpenGL和C ++中实现framebuffer对象。

基本上，我有一个处理framebuffer对象功能的类。但是，在渲染到帧缓冲区然后使用帧缓冲区作为纹理之后，唯一绘制的是命令glClearColor中的蓝色。

看看这段代码，我错过了什么吗？

void FrameBuffer::initFrameBufferDepthBuffer(void) {

    glGenRenderbuffers(1, &fbo_depth); // Generate one render buffer and store the ID in fbo_depth
    glBindRenderbuffer(GL_RENDERBUFFER, fbo_depth); // Bind the fbo_depth render buffer

    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, window_width, window_height); // Set the render buffer storage to be a depth component, with a width and height of the window

    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, fbo_depth); // Set the render buffer of this buffer to the depth buffer

    bool status = glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE;
    if(!status){
        std::cout << "Error during depth buffer\n";
    }
    glBindRenderbuffer(GL_RENDERBUFFER, 0); // Unbind the render buffer
}

void FrameBuffer::initFrameBufferTexture(void) {
    glGenTextures(1, &fbo_texture); // Generate one texture
    glBindTexture(GL_TEXTURE_2D, fbo_texture); // Bind the texture fbo_texture

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, window_width, window_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // Create a standard texture with the width and height of our window

    // Setup the basic texture parameters
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,getTexture(), 0);

    // Unbind the texture
    glBindTexture(GL_TEXTURE_2D, 0);

    bool status =  glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE;;
    if(!status){
        std::cout << "Error during texture buffer\n";
    }
}

void FrameBuffer::create(void) {

    glGenFramebuffers(1, &fbo); // Generate one frame buffer and store the ID in fbo
    glBindFramebuffer(GL_FRAMEBUFFER, fbo); // Bind our frame buffer
    initFrameBufferDepthBuffer(); // Initialize our frame buffer depth buffer

    initFrameBufferTexture(); // Initialize our frame buffer texture

    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, fbo_texture, 0); // Attach the texture fbo_texture to the color buffer in our frame buffer

    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, fbo_depth); // Attach the depth buffer fbo_depth to our frame buffer

    GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER); // Check that status of our generated frame buffer

    if (status != GL_FRAMEBUFFER_COMPLETE) // If the frame buffer does not report back as complete
    {
        std::cout << "Couldn't create frame buffer" << std::endl; // Output an error to the console
        exit(0); // Exit the application
    }

    glBindFramebuffer(GL_FRAMEBUFFER, 0); // Unbind our frame buffer
}





void FrameBuffer::bindTexture() {
    glBindTexture(GL_TEXTURE_2D, fbo_texture); // Bind our frame buffer texture
}
void FrameBuffer::unbindTexture() {
    glBindTexture(GL_TEXTURE_2D, 0); // Bind our frame buffer texture
}

void FrameBuffer::bind() {
    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
}

void FrameBuffer::unbind() {
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

void FrameBuffer::startUse() {
    bind();
    glPushAttrib(GL_VIEWPORT_BIT | GL_ENABLE_BIT); // Push our glEnable and glViewport states
    glViewport(0, 0, window_width, window_height); // Set the size of the frame buffer view port


    glMatrixMode( GL_PROJECTION ); //Switch to setting the camera perspective
    float ratio = (GLfloat)window_width/(GLfloat)window_height; //Set the camera perspective

    glLoadIdentity(); //reset the camera
    gluPerspective( 60.0f, ratio, 0.1f,  100.0f );


    glMatrixMode(GL_MODELVIEW);

    glClearColor (0.0f, 0.0f, 1.0f, 1.0f); // Set the clear colour
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear the depth and colour buffers
    glLoadIdentity();

}

void FrameBuffer::stopUse() {
    glPopAttrib(); // Restore our glEnable and glViewport states
    unbind();
}

void FrameBuffer::destroy() {
    glDeleteFramebuffers(1,&this->fbo);
    glDeleteTextures(1,&fbo_texture);
    glDeleteRenderbuffers(1,&fbo_depth);
}

unsigned int FrameBuffer::getTexture() {
    return fbo_texture;
}

Answer 1

发布后，问题被识别为我没有启用纹理使用以下命令：

glEnable ( GL_TEXTURE_2D )

这可以解决问题。我希望这些代码能让其他代码受益。

framebuffer接受渲染命令？

1 个答案: