glCheckFramebufferStatus

Name

glCheckFramebufferStatus — return the framebuffer completeness status of a framebuffer object

C Specification

GLenum glCheckFramebufferStatus( GLenum target);

Parameters

target: Specifies the target framebuffer object. The symbolic constant must be GL_FRAMEBUFFER.

Description

glCheckFramebufferStatus returns a symbolic constant that identifies whether or not the currently bound framebuffer is framebuffer complete, and if not, which of the rules of framebuffer completeness is violated.

If the framebuffer is complete, then GL_FRAMEBUFFER_COMPLETE is returned. If the framebuffer is not complete, the return values are as follows:

GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT

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.

Color-renderable formats include GL_RGBA4, GL_RGB5_A1, and GL_RGB565. GL_DEPTH_COMPONENT16 is the only depth-renderable format. GL_STENCIL_INDEX8 is the only stencil-renderable format.

GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS

Not all attached images have the same width and height.

GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT

No images are attached to the framebuffer.

GL_FRAMEBUFFER_UNSUPPORTED

The combination of internal formats of the attached images violates an implementation-dependent set of restrictions.

If the currently bound framebuffer is not framebuffer complete, then it is an error to attempt to use the framebuffer for writing or reading. This means that rendering commands (glClear, glDrawArrays, and glDrawElements) as well as commands that read the framebuffer (glReadPixels, glCopyTexImage2D, and glCopyTexSubImage2D) will generate the error GL_INVALID_FRAMEBUFFER_OPERATION if called while the framebuffer is not framebuffer complete.

Notes

It is strongly advised, thought not required, that an application call glCheckFramebufferStatus to see if the framebuffer is complete prior to rendering. This is because some implementations may not support rendering to particular combinations of internal formats. In this case, GL_FRAMEBUFFER_UNSUPPORTED is returned.

The default window-system-provided framebuffer is always framebuffer complete, and thus GL_FRAMEBUFFER_COMPLETE is returned when GL_FRAMEBUFFER_BINDING is 0.

Additionally, if an error occurs, zero is returned.

Errors

GL_INVALID_ENUM is generated if target is not GL_FRAMEBUFFER.