Multipass FrameBuffer

beginners
#1

hello! im trying to do a multipass shader and i need to get the texture of the previus buffer.
doing this, i get only a red color:

gBuffer

    glGenFramebuffers(1, &gBuffer);
    glBindFramebuffer(GL_FRAMEBUFFER, gBuffer);
    
    glGenTextures(1, &gColor);
    glBindTexture(GL_TEXTURE_2D, gColor);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, width, height, 0, GL_RGBA, GL_FLOAT, NULL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, gColor, 0);
    
    //
    glGenTextures(1, &gPosition);
    glBindTexture(GL_TEXTURE_2D, gPosition);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_FLOAT, NULL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, gPosition, 0);
    
    glGenTextures(1, &gAlbedo);
    glBindTexture(GL_TEXTURE_2D, gAlbedo);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_FLOAT, NULL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, GL_TEXTURE_2D, gAlbedo, 0);
    
    glGenTextures(1, &gDepth);
    glBindTexture(GL_TEXTURE_2D, gDepth);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_R16F, width, height, 0, GL_RGB, GL_FLOAT, NULL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT3, GL_TEXTURE_2D, gDepth, 0);
    
    GLuint attachments[4] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2, GL_COLOR_ATTACHMENT3 };
    glDrawBuffers(4, attachments);
    
    GLuint rboDepth;
    glGenRenderbuffers(1, &rboDepth);
    glBindRenderbuffer(GL_RENDERBUFFER, rboDepth);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, width, height);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rboDepth);
    
    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        std::cout << "Framebuffer not complete!" << std::endl;
    
    glBindFramebuffer(GL_FRAMEBUFFER, 0);

firstBuffer (until here everything is ok, i can get the texture from the gBuffer)

    glGenFramebuffers(1, &buffer_firstPass);
    glBindFramebuffer(GL_FRAMEBUFFER, buffer_firstPass);
    
    glGenTextures(1, &buffer_firstPassTexture);
    glBindTexture(GL_TEXTURE_2D, buffer_firstPassTexture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_R16F, width, height, 0, GL_RGB, GL_FLOAT, NULL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, buffer_firstPassTexture, 0);
    
    GLuint attachments[1] = { GL_COLOR_ATTACHMENT0};
    glDrawBuffers(1, attachments);
    
    GLuint rboDepth;
    glGenRenderbuffers(1, &rboDepth);
    glBindRenderbuffer(GL_RENDERBUFFER, rboDepth);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, width, height);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rboDepth);
    
    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        std::cout << "Framebuffer not complete!" << std::endl;
    
    glBindFramebuffer(GL_FRAMEBUFFER, 0);

second pass

    glGenFramebuffers(1, &buffer_secondPass);
    glBindFramebuffer(GL_FRAMEBUFFER, buffer_secondPass);
    
    glGenTextures(1, &buffer_secondPass);
    glBindTexture(GL_TEXTURE_2D, buffer_secondPass);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_R16F, width, height, 0, GL_RGB, GL_FLOAT, NULL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, buffer_secondPass, 0);
    
    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        std::cout << "SSAO Framebuffer not complete!" << std::endl;
    
    glBindFramebuffer(GL_FRAMEBUFFER, 0);

here is the problem. i need to use in the second pass the first pass, using shaders:

glBindFramebuffer(GL_FRAMEBUFFER, buffer_firstPass);

    glClear(GL_COLOR_BUFFER_BIT);

    firstPassShader.shader.begin();
    firstPassShader.shader.setUniformTexture("gColor", GL_TEXTURE_2D, gColor,0);
    firstPassShader.shader.setUniformTexture("gPosition", GL_TEXTURE_2D, gPosition, 1);
    firstPassShader.shader.setUniformTexture("gDepth", GL_TEXTURE_2D, gDepth, 2);
    firstPassShader.shader.setUniformTexture("gAlbedo", GL_TEXTURE_2D, gAlbedo, 3);
    quad.draw(OF_MESH_FILL);
    firstPassShader.shader.end();

    glBindFramebuffer(GL_FRAMEBUFFER, 0);

    ////////////////////////////////////////////////////////
//
    glBindFramebuffer(GL_FRAMEBUFFER, buffer_secondPass);

    glClear(GL_COLOR_BUFFER_BIT);
    secondPassShader.shader.begin();
     secondPassShader.shader.setUniformTexture("gColor", GL_TEXTURE_2D, gColor,0);
    secondPassShader.shader.setUniformTexture("gPrev", GL_TEXTURE_2D, buffer_firstPassTexture, 1);
    quad.draw();
//
    secondPassShader.shader.end();
    glBindFramebuffer(GL_FRAMEBUFFER, 0);