_p_l_a_n_e Specifies a clipping plane. The number of clipping planes
depends on the implementation, but at least six clipping planes
are supported. They are identified by symbolic names of the
form GGGGLLLL____CCCCLLLLIIIIPPPP____PPPPLLLLAAAANNNNEEEEi where 0 _< i < GGGGLLLL____MMMMAAAAXXXX____CCCCLLLLIIIIPPPP____PPPPLLLLAAAANNNNEEEESSSS.
_e_q_u_a_t_i_o_n Returns four double-precision values that are the coefficients
of the plane equation of _p_l_a_n_e in eye coordinates. The initial
value is (0, 0, 0, 0).
DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
ggggllllGGGGeeeettttCCCClllliiiippppPPPPllllaaaannnneeee returns in _e_q_u_a_t_i_o_n the four coefficients of the plane
equation for _p_l_a_n_e.
NNNNOOOOTTTTEEEESSSS
It is always the case that GGGGLLLL____CCCCLLLLIIIIPPPP____PPPPLLLLAAAANNNNEEEEi = GGGGLLLL____CCCCLLLLIIIIPPPP____PPPPLLLLAAAANNNNEEEE0000 + i.
If an error is generated, no change is made to the contents of _e_q_u_a_t_i_o_n.
EEEERRRRRRRROOOORRRRSSSS
GGGGLLLL____IIIINNNNVVVVAAAALLLLIIIIDDDD____EEEENNNNUUUUMMMM is generated if _p_l_a_n_e is not an accepted value.
GGGGLLLL____IIIINNNNVVVVAAAALLLLIIIIDDDD____OOOOPPPPEEEERRRRAAAATTTTIIIIOOOONNNN is generated if ggggllllGGGGeeeettttCCCClllliiiippppPPPPllllaaaannnneeee is executed between
the execution of ggggllllBBBBeeeeggggiiiinnnn and the corresponding execution of ggggllllEEEEnnnndddd.