glBlitFramebuffer() renders empty screen when fragment out is vec3

Question

I am using OpenGL 4.0, formerly was using 3.3 I have a fragment shader with 3 outputs -each one is vec3 .I am writing these outputs to some FBO then trying to test the content using The glBlitFramebuffer() method.I am getting the empty screen.Now ,I figured out that setting the outputs to be of vec4 type works correctly.I don't understand why! My FBO textures are set to RGB32F so they should be able to accept vec3 from fragments. Here is my FBO setup (That is Java LWJGL wrapper but it doesn't matter here):

    _fbo = glGenFramebuffers();
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, _fbo);


    glGenTextures(m_textures);
    _depthTexture = glGenTextures();


   for (int i = 0; i < GBUFFER_NUM_TEXTURES; i++) {


        glBindTexture(GL_TEXTURE_2D, m_textures.get(i));//
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB32F, width, height, 0, GL_RGB, GL_FLOAT, (ByteBuffer) null);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

        glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0+i , GL_TEXTURE_2D,m_textures.get(i), 0);//

    }

    // depth
    glBindTexture(GL_TEXTURE_2D, _depthTexture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT32F, width, height, 0, GL_DEPTH_COMPONENT, GL_FLOAT, (ByteBuffer) null);
    glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, _depthTexture, 0);





    DrawBuffers = BufferUtils.createIntBuffer(GBUFFER_NUM_TEXTURES);

      DrawBuffers.put(0, GL_COLOR_ATTACHMENT0);
      DrawBuffers.put(1, GL_COLOR_ATTACHMENT1);
      DrawBuffers.put(2, GL_COLOR_ATTACHMENT2);



     glDrawBuffers(DrawBuffers);

Do you check your shaders for compile errors and warnings (get the infologs)? Those may be more enlightening. — Tim, Jul 02 '12 at 18:01
I am checking for shader program link errors. It compiles fine in both case — Michael IV, Jul 02 '12 at 18:18
Where is your shader? How do you know that you're not getting any rendering? — Nicol Bolas, Jul 02 '12 at 19:40
Because the blitting results in black screen. But once I change the output fragment color data type to vec4 it shows ok. — Michael IV, Jul 02 '12 at 20:37

glBlitFramebuffer() renders empty screen when fragment out is vec3

0 Answers0