glGetError
NAME
glGetError -- return error information
C SPECIFICATION
GLenum glGetError(void 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.
ERRORS
GL_INVALID_OPERATION is generated if glGetError is called between
a call to glBegin and the corresponding
call to glEnd.
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© 1995 Uwe Behrens. All rights reserved.