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_ERRORNo error has been recorded. The value of this symbolic constant is guaranteed to be 0.
GL_INVALID_ENUMAn 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_VALUEA 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_OPERATIONThe 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_OVERFLOWThis 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_UNDERFLOWThis 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_MEMORYThere 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_LARGEThe 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_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.
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.