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glGetError - return error information
GLenum glGetError(
void )
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 command 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 overflow. 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 underflow. 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 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
- 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 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 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.
GL_TABLE_TOO_LARGE was introduced in GL version 1.2.
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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