_m_o_d_e_l Specifies a modelview matrix (as from a ggggllllGGGGeeeettttFFFFllllooooaaaattttvvvv call).
_p_e_r_s_p_e_c_t_i_v_e Specifies a projection matrix (as from a ggggllllGGGGeeeettttFFFFllllooooaaaattttvvvv call).
_v_i_e_w Specifies a viewport (as from a ggggllllGGGGeeeettttIIIInnnntttteeeeggggeeeerrrrvvvv call).
DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
gggglllluuuuLLLLooooaaaaddddSSSSaaaammmmpppplllliiiinnnnggggMMMMaaaattttrrrriiiicccceeeessss uses _m_o_d_e_l, _p_e_r_s_p_e_c_t_i_v_e, and _v_i_e_w to recompute
the sampling and culling matrices stored in _n_u_r_b. The sampling matrix
determines how finely a NURBS curve or surface must be tessellated to
satisfy the sampling tolerance (as determined by the
GGGGLLLLUUUU____SSSSAAAAMMMMPPPPLLLLIIIINNNNGGGG____TTTTOOOOLLLLEEEERRRRAAAANNNNCCCCEEEE property). The culling matrix is used in deciding
if a NURBS curve or surface should be culled before rendering (when the
GGGGLLLLUUUU____CCCCUUUULLLLLLLLIIIINNNNGGGG property is turned on).
gggglllluuuuLLLLooooaaaaddddSSSSaaaammmmpppplllliiiinnnnggggMMMMaaaattttrrrriiiicccceeeessss is necessary only if the GGGGLLLLUUUU____AAAAUUUUTTTTOOOO____LLLLOOOOAAAADDDD____MMMMAAAATTTTRRRRIIIIXXXX
property is turned off (see gggglllluuuuNNNNuuuurrrrbbbbssssPPPPrrrrooooppppeeeerrrrttttyyyy). Although it can be
convenient to leave the GGGGLLLLUUUU____AAAAUUUUTTTTOOOO____LLLLOOOOAAAADDDD____MMMMAAAATTTTRRRRIIIIXXXX property turned on, there
can be a performance penalty for doing so. (A round trip to the GL
server is needed to fetch the current values of the modelview matrix,