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Editorial Team
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Asked: 2026-05-26T23:33:00+00:00

With the following code: GLuint viewRenderbuffer, viewFramebuffer, viewDepthbuffer, stencilBuffer; // Create the framebuffer object

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With the following code:

GLuint viewRenderbuffer, viewFramebuffer, viewDepthbuffer, stencilBuffer;
// Create the framebuffer object
glGenFramebuffers(1, &viewFramebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);

// Create a render buffer and bind it to the FBO.
glGenRenderbuffers(1, &viewRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
[context renderbufferStorage:GL_RENDERBUFFER fromDrawable:(CAEAGLLayer*)self.layer];
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, viewRenderbuffer);
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &imageWidth);
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &imageHeight);

// Create a depth buffer and bind it to the FBO.
glGenRenderbuffers(1, &viewDepthbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, viewDepthbuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, imageWidth, imageHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, viewDepthbuffer);

// Create a stencil buffer to crop the rendered scene and bind it to the FBO.
glGenRenderbuffers(1, &stencilBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, stencilBuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_STENCIL_INDEX, imageWidth, imageHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, stencilBuffer);

// Check the FBO.
if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
    NSLog(@"Failure with framebuffer generation: %d", glCheckFramebufferStatus(GL_FRAMEBUFFER));
}

With GL_STENCIL_INDEX, I get the GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT error. With GL_STENCIL_INDEX8, I get the GL_FRAMEBUFFER_UNSUPPORTED error. Both are caused by the last glFramebufferRenderbuffer() function, which should bind the stencil buffer to the FBO.

Furthermore, when I check the GL_RENDERBUFFER_STENCIL_SIZE value, I get the right value (8) with GL_STENCIL_INDEX8, but I get 0 with GL_STENCIL_INDEX.

With this, I can’t get a functional and complete FBO with a stencil buffer. Is it due to the GL_STENCIL_INDEX? Which one should be used here?

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1 Answer

  1. Editorial Team

    It seems that in OpenGL ES 2.0 at least on iOS (not sure for other OS) you have to create combine the depth buffer and the stencil buffer.
    I listed all the extensions supported on my device (iPhone 4 with iOS 5.0.1) and the only one related to the stencil buffer is :

    GL_OES_packed_depth_stencil

    This suggests that you would have to create a combo depth+stencil buffer (taken from the iPhone 3D Programming book)

    // Create a packed depth stencil buffer.
GLuint depthStencil;
glGenRenderbuffersOES(1, &depthStencil);
glBindRenderbufferOES(GL_RENDERBUFFER_OES, depthStencil);
glRenderbufferStorageOES(GL_RENDERBUFFER_OES, GL_DEPTH24_STENCIL8_OES, width, height);

// Create the framebuffer object.
GLuint framebuffer;
glGenFramebuffersOES(1, &framebuffer);
glBindFramebufferOES(GL_FRAMEBUFFER_OES, framebuffer);
glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES,
                             GL_RENDERBUFFER_OES, color);
glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_DEPTH_ATTACHMENT_OES,
                                GL_RENDERBUFFER_OES, depthStencil);
glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_STENCIL_ATTACHMENT_OES,
                             GL_RENDERBUFFER_OES, depthStencil);
glBindRenderbufferOES(GL_RENDERBUFFER_OES, color);
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