_t_e_s_s Specifies the tessellation object (created with gggglllluuuuNNNNeeeewwwwTTTTeeeessssssss).
_d_a_t_a Specifies a pointer to user polygon data.
DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
gggglllluuuuTTTTeeeessssssssBBBBeeeeggggiiiinnnnPPPPoooollllyyyyggggoooonnnn and gggglllluuuuTTTTeeeessssssssEEEEnnnnddddPPPPoooollllyyyyggggoooonnnn delimit the definition of a
convex, concave or self-intersecting polygon. Within each
gggglllluuuuTTTTeeeessssssssBBBBeeeeggggiiiinnnnPPPPoooollllyyyyggggoooonnnn/gggglllluuuuTTTTeeeessssssssEEEEnnnnddddPPPPoooollllyyyyggggoooonnnn pair, there must be one or more
calls to gggglllluuuuTTTTeeeessssssssBBBBeeeeggggiiiinnnnCCCCoooonnnnttttoooouuuurrrr/gggglllluuuuTTTTeeeessssssssEEEEnnnnddddCCCCoooonnnnttttoooouuuurrrr. Within each contour,
there are zero or more calls to gggglllluuuuTTTTeeeessssssssVVVVeeeerrrrtttteeeexxxx. The vertices specify a
closed contour (the last vertex of each contour is automatically linked
to the first). See the gggglllluuuuTTTTeeeessssssssVVVVeeeerrrrtttteeeexxxx, gggglllluuuuTTTTeeeessssssssBBBBeeeeggggiiiinnnnCCCCoooonnnnttttoooouuuurrrr, and
gggglllluuuuTTTTeeeessssssssEEEEnnnnddddCCCCoooonnnnttttoooouuuurrrr reference pages for more details.
_d_a_t_a is a pointer to a user-defined data structure. If the appropriate
callback(s) are specified (see gggglllluuuuTTTTeeeessssssssCCCCaaaallllllllbbbbaaaacccckkkk), then this pointer is
returned to the callback function(s). Thus, it is a convenient way to
store per-polygon information.
Once gggglllluuuuTTTTeeeessssssssEEEEnnnnddddPPPPoooollllyyyyggggoooonnnn is called, the polygon is tessellated, and the
resulting triangles are described through callbacks. See gggglllluuuuTTTTeeeessssssssCCCCaaaallllllllbbbbaaaacccckkkk
for descriptions of the callback functions.
EEEEXXXXAAAAMMMMPPPPLLLLEEEE
A quadrilateral with a triangular hole in it can be described as follows: