glGetError(3G) OpenGL Reference glGetError(3G)
NAME
glGetError - return error information
C SPECIFICATION
GLenum glGetError( void )
DESCRIPTION
glGetError returns the value of the error flag. Each detectable error is
assigned a numeric code and symbolic name. When an error occurs, the
error flag is set to the appropriate error code value. No other errors
are recorded until glGetError is called, the error code is returned, and
the flag is reset to GLNOERROR. If a call to glGetError returns
GLNOERROR, there has been no detectable error since the last call to
glGetError, or since the GL was initialized.
To allow for distributed implementations, there may be several error
flags. If any single error flag has recorded an error, the value of that
flag is returned and that flag is reset to GLNOERROR when glGetError is
called. If more than one flag has recorded an error, glGetError returns
and clears an arbitrary error flag value. Thus, glGetError should always
be called in a loop, until it returns GLNOERROR, if all error flags are
to be reset.
Initially, all error flags are set to GLNOERROR.
The following errors are currently defined:
GLNOERROR No error has been recorded. The value of
this symbolic constant is guaranteed to be
0.
GLINVALIDENUM An unacceptable value is specified for an
enumerated argument. The offending command
is ignored, and has no other side effect
than to set the error flag.
GLINVALIDVALUE A numeric argument is out of range. The
offending command is ignored, and has no
other side effect than to set the error
flag. This flag is also set when the
implementation cannot accomodate an image
of the size requested by glTexImage3DExt,
glTexImage2D, or glTexImage1D. The error
is not generated for a
GLPROXYTEXTURE3DEXT, a
GLPROXYTEXTURE2DEXT, or a
GLPROXYTEXTURE1DEXT.
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glGetError(3G) OpenGL Reference glGetError(3G)
GLINVALIDOPERATION The specified operation is not allowed in
the current state. The offending command
is ignored, and has no other side effect
than to set the error flag.
GLSTACKOVERFLOW This command would cause a stack overflow.
The offending command is ignored, and has
no other side effect than to set the error
flag.
GLSTACKUNDERFLOW This command would cause a stack underflow.
The offending command is ignored, and has
no other side effect than to set the error
flag.
GLOUTOFMEMORY There is not enough memory left to execute
the command. The state of the GL is
undefined, except for the state of the
error flags, after this error is recorded.
GLTABLETOOLARGEEXT The implementation cannot accomodate a
table of the size requested by
glHistogramEXT. The error is not generated
for GLPROXYHISTOGRAMEXT.
When an error flag is set, results of a GL operation are undefined only
if GLOUTOFMEMORY has occurred. In all other cases, the command
generating the error is ignored and has no effect on the GL state or
frame buffer contents. If the generating command returns a value, it
returns 0. If glGetError itself generates an error, it returns 0.
ERRORS
GLINVALIDOPERATION is generated if glGetError is executed between the
execution of glBegin and the corresponding execution of glEnd. In this
case glGetError returns 0.
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