Why is this OpenGL framebuffer color attachment incomplete?

Question

I've been following this tutorial on rendering to an off-screen texture, but I'm having difficulty creating the render target. I've registered an error callback function and I'm getting a GL_DEBUG_TYPE_OTHER error back with a GL_DEBUG_SOURCE_API source, which is getting spat out by glCheckNamedFramebufferStatus() with the message:

FBO incomplete: color attachment incomplete[0].

I'm struggling to see what I'm missing here, I've double checked the parameters that I'm passing into the OpenGL functions and tried removing the glTexParameteri calls but to no avail.

Any help would be greatly appreciated.

GLuint framebuffer = 0;
GLuint renderedTexture;
GLenum drawBuffers[1] = {GL_COLOR_ATTACHMENTS0};

bool buildOffscreenBuffer()
{
    // creating frame & render texture to draw picker buffer to
    glGenFramebuffers(1,  &framebuffer);
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
    glGenTextures(1, &renderedTexture);
                                                                                              
    glBindTexture(GL_TEXTURE_2D, renderedTexture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 1920, 1080,
            0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
                                                                                              
    // configuring framebuffer
    glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
            renderedTexture, 0);
    glDrawBuffers(1, drawBuffers);
                                                                                              
    return glCheckNamedFramebufferStatus(framebuffer, GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE;
}

Update: As per derhass' answer, it seems that GL_RGB isn't required as per the spec. I've tried updating this to GL_RGBA but I'm getting the same error. Since this may be implementation related, I'll list my card and driver:

Card: RX Vega 56

Driver: mesa/amdgpu

Please provide an example which actually produces the issue. Btw, you might check my dirty FBO example (compile via gcc HelloFBO.c -lglfw -lGLEW -lGL), I'd be surprised if that wouldn't run on mesa/amdgpu. Just add the framebuffer completness checks, and change the FBO dimensions if you like. — derhass
– derhass, Commented Nov 27, 2020 at 18:45

derhass · Accepted Answer · 2020-11-26 22:51:28Z

3

As per the GL spec, GL_RGB is not in the set of required renderable formats, so implementations are free to not support it. Try GL_RGBA instead.

answered Nov 26, 2020 at 22:51

derhass

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3 Comments

Mokou Over a year ago

Same error with GL_RGBA I'm afraid. I didn't realise that GL_RGB wasn't required by the spec. I'll update the question with some driver information

derhass Over a year ago

You still haven't updated the source code for the texture format.

Mokou Over a year ago

My bad, looked at this first thing in the morning and I missed that in the update

Mokou · Accepted Answer · 2020-11-29 12:00:06Z

0

Managed to get to the bottom of this. I'd actually fixed the bug in simplifying the example for the post.

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 1920, 1080,
            0, GL_RGBA, GL_UNSIGNED_BYTE, 0);

Was actually getting the width and height from a helper function that from a platform layer, however that function returned a struct {int, int} that I was storing in a struct {float, float} . This resulted in garbage being passed as the width and height to glTexImage2D.

answered Nov 29, 2020 at 12:00

Mokou

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