glgeterror
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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 GL_NO_ERROR. If a call to glGetError returns
GL_NO_ERROR, 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 GL_NO_ERROR 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 GL_NO_ERROR, if all error flags are
to be reset.
Initially, all error flags are set to GL_NO_ERROR.
The currently defined errors are as follows:
GL_NO_ERROR No error has been recorded. The value of
this symbolic constant is guaranteed to be
zero.
GL_INVALID_ENUM An unacceptable value is specified for an
enumerated argument. The offending command
is ignored, having no side effect other
than to set the error flag.
GL_INVALID_VALUE A numeric argument is out of range. The
offending command is ignored, having no
side effect other than to set the error
flag.
GL_INVALID_OPERATION The specified operation is not allowed in
the current state. The offending command
is ignored, having no side effect other
than to set the error flag.
GL_STACK_OVERFLOW This command would cause a stack overflow.
The offending command is ignored, having no
side effect other than to set the error
flag.
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glGetError(3G) OpenGL Reference glGetError(3G)
GL_STACK_UNDERFLOW This command would cause a stack underflow.
The offending command is ignored, having no
side effect other than to set the error
flag.
GL_OUT_OF_MEMORY 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.
GL_TABLE_TOO_LARGE_EXT The implementation cannot accomodate a
table of the size requested by
glHistogramEXT. The error is not generated
for GL_PROXY_HISTOGRAM_EXT.
GL_TEXTURE_TOO_LARGE_EXT The implementation cannot accomodate an
image of the size requested by
glTexImage3DExt, glTexImage2D, or
glTexImage1D. The error is not generated
for a GL_PROXY_TEXTURE_3D_EXT, a
GL_PROXY_TEXTURE_2D_EXT, or a
GL_PROXY_TEXTURE_1D_EXT.
When an error flag is set, results of a GL operation are undefined only
if GL_OUT_OF_MEMORY 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 zero. If glGetError itself generates an error it returns zero.
ERRORS
GL_INVALID_OPERATION is generated if glGetError is executed between the
execution of glBegin and the corresponding execution of glEnd. In this
case glGetError returns zero.
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