glGetError(3)

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 following errors are currently defined:

       GL_NO_ERROR                   No error has been recorded.  The value of
                                     this symbolic constant is  guaranteed  to
                                     be 0.

       GL_INVALID_ENUM               An unacceptable value is specified for an
                                     enumerated argument.  The offending  com-
                                     mand  is  ignored,  and has no other side
                                     effect than to set the error flag.

       GL_INVALID_VALUE              A numeric argument is out of range.   The
                                     offending  command is ignored, and has no
                                     other side effect than to set  the  error
                                     flag.

       GL_INVALID_OPERATION          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.

       GL_STACK_OVERFLOW             This command would cause  a  stack  over-
                                     flow.   The offending command is ignored,
                                     and has no other side effect than to  set
                                     the error flag.

       GL_STACK_UNDERFLOW            This  command  would cause a stack under-
                                     flow.  The offending command is  ignored,
                                     and  has no other side effect than to set
                                     the error flag.

       GL_OUT_OF_MEMORY              There is not enough memory left  to  exe-
                                     cute 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            The specified table exceeds the implemen-
                                     tation's  maximum  supported  table size.
                                     The offending command is ignored, and has
                                     no  other  side  effect  than  to set the
                                     error flag.

       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 gen-
       erating 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.

NOTES

       GL_TABLE_TOO_LARGE was introduced in GL version 1.2.

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 0.

                                                                GLGETERROR(3G)