_t_o_k_e_n Specifies a marker value to be placed in the feedback buffer
following a GGGGLLLL____PPPPAAAASSSSSSSS____TTTTHHHHRRRROOOOUUUUGGGGHHHH____TTTTOOOOKKKKEEEENNNN.
DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
Feedback is a GL render mode. The mode is selected by calling
ggggllllRRRReeeennnnddddeeeerrrrMMMMooooddddeeee with GGGGLLLL____FFFFEEEEEEEEDDDDBBBBAAAACCCCKKKK. When the GL is in feedback mode, no
pixels are produced by rasterization. Instead, information about
primitives that would have been rasterized is fed back to the application
using the GL. See the ggggllllFFFFeeeeeeeeddddbbbbaaaacccckkkkBBBBuuuuffffffffeeeerrrr reference page for a description
of the feedback buffer and the values in it.
ggggllllPPPPaaaassssssssTTTThhhhrrrroooouuuugggghhhh inserts a user-defined marker in the feedback buffer when
it is executed in feedback mode. _t_o_k_e_n is returned as if it were a
primitive; it is indicated with its own unique identifying value:
GGGGLLLL____PPPPAAAASSSSSSSS____TTTTHHHHRRRROOOOUUUUGGGGHHHH____TTTTOOOOKKKKEEEENNNN. The order of ggggllllPPPPaaaassssssssTTTThhhhrrrroooouuuugggghhhh commands with respect
to the specification of graphics primitives is maintained.
NNNNOOOOTTTTEEEESSSS
ggggllllPPPPaaaassssssssTTTThhhhrrrroooouuuugggghhhh is ignored if the GL is not in feedback mode.
EEEERRRRRRRROOOORRRRSSSS
GGGGLLLL____IIIINNNNVVVVAAAALLLLIIIIDDDD____OOOOPPPPEEEERRRRAAAATTTTIIIIOOOONNNN is generated if ggggllllPPPPaaaassssssssTTTThhhhrrrroooouuuugggghhhh is executed between
the execution of ggggllllBBBBeeeeggggiiiinnnn and the corresponding execution of ggggllllEEEEnnnndddd.