glGetError.3gl

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.

  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.

  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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Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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