gluErrorString - produce an error string from a GL or GLU error code.
const GLubyte * gluErrorString (GLenum error);
gluErrorString produces an error string from a GL or GLU error code. The string is in ISO Latin 1 format. For example, gluErrorString(GL_OUT_OF_MEMORY); returns the string out of memory.
The standard GLU error codes are GLU_INVALID_ENUM, GLU_INVALID_VALUE, and GLU_OUT_OF_MEMORY. Certain other GLU functions can return special- ized error codes through callbacks. See the glGetError reference page for the list of GL error codes.
NULL is returned if error is not a valid GL or GLU error code.
glGetError, gluNurbsCallback, gluQuadricCallback, gluTessCallback.