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glGetError(3G)


NAME

  glGetError - return error information


SYNOPSIS

  GLenum glGetError(
	  void );


DESCRIPTION

  glGetError() returns the value of the error option.  Each detectable error
  is assigned a numeric code and symbolic name. When an error occurs, the
  error option is set to the appropriate error code value.  No other errors
  are recorded until glGetError() is called, the error code is returned, and
  the option 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
  options. If any single error option has recorded an error, the value of
  that option is returned and that option is reset to GL_NO_ERROR when
  glGetError() is called. If more than one option has recorded an error,
  glGetError() returns and clears an arbitrary error option value. Thus,
  glGetError() should always be called in a loop, until it returns
  GL_NO_ERROR, if all error options are to be reset.

  Initially, all error options 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 command is ignored, and has no other side effect than to set
      the error option.

  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 option.

  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 option.

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

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

  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 options, after
      this error is recorded.

  GL_TABLE_TOO_LARGE
      The specified table exceeds the implementation's maximum supported
      table size.  The offending command is ignored, and has no other side
      effect than to set the error option.

  When an error option 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 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.

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