CODEWITHSUNDEEP
opengltexturesfbo
lien
lien

Reputation: 63

GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT from the shared second context

I need to share the color/depth/stencil buffers between two OpenGL contexts. 2D textures are attached to framebuffer object for the buffers. The code looks like below:

// === Start of context 1
//
Create _hDC1, _hRC1;
wglMakeCurrent(hDC1, hRC1);
glGenFramebuffers(1, &_FBO1);
glBindFramebuffer(GL_FRAMEBUFFER, _FBO1);

// color buffer
glGenTextures(1, &_color1);
glBindTexture(GL_TEXTURE2D, _color1);
glTexParameteri(GL_TEXTURE_2D, ..., ); // GL_TEXTURE_WRAP_S, ..., etc.
glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGBA16F, 512, 512);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, _color1, 0);

// depth buffer
glGenTextures(1, &_depth1);
glBindTexture(GL_TEXTURE2D, _depth1);
glTexParameteri(GL_TEXTURE_2D, ..., ); // GL_TEXTURE_WRAP_S, ..., etc.
glTexStorage2D(GL_TEXTURE_2D, 1, GL_DEPTH24_STENCIL8, 512, 512);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, _depth1, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_TEXTURE_2D, _depth1, 0);

// check completeness
GLenum  status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
assert(status == GL_FRAMEBUFFER_COMPLETE); // *pass fine here*

// detach _FBO1
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, 0, 0);
glReadBuffer(GL_NONE);
glDrawBuffer(GL_NONE);
//
// === End of context 1


// === Start of context 2
//
Create _hDC2, _hRC2; // pixel format is same as _hDC1
wglShareLists(_hRC2, hRC1); // share objects between _hRC1 and _hRC2
wglMakeCurrent(_hDC2, _hRC2);

// Create another frame buffer, since it is not sharable
glGenFramebuffers(1, &_FBO2);
glBindFramebuffer(GL_FRAMEBUFFER, _FBO2);

// Use the shared textures for color/depth/stencil buffers
glBindTexture(GL_TEXTURE2D, _color1);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, _color1, 0);
glBindTexture(GL_TEXTURE2D, _depth1);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, _depth1, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_TEXTURE_2D, _depth1, 0);

// check completeness
GLenum  status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
assert(status == GL_FRAMEBUFFER_COMPLETE); // *fail here, status is GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT*
//
// === End of context 2

The second completeness check always fails.

From https://www.khronos.org/opengles/sdk/docs/man/xhtml/glCheckFramebufferStatus.xml

Not all framebuffer attachment points are framebuffer attachment complete. This means that at least one attachment point with a renderbuffer or texture attached has its attached object no longer in existence or has an attached image with a width or height of zero, or the color attachment point has a non-color-renderable image attached, or the depth attachment point has a non-depth-renderable image attached, or the stencil attachment point has a non-stencil-renderable image attached.

Can not figure out what's get missed. Checked several posts online, but none of them is the same use case as mine.

Upvotes: 1

Views: 1239

Answers (1)

lien
lien

Reputation: 63

Aha, I messed up with the arguments order when calling wglShareLists(), which should be:

wglShareLists(_hRC1, hRC2);

Everything works now. I should have put an error check around it.

Upvotes: 1

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