In two dimensions, the glMapGrid2*() and glEvalMesh2() commands are similar to the one-dimensional versions, except that both u and v information must be included:
void glMapGrid2{fd}(
GLint nu, TYPEu1, TYPEu2,
GLint nv, TYPEv1, TYPEv2 );
glMapGrid2*() defines a two-dimensional map grid that goes from u1 to u2
in nu evenly spaced steps and from v1 to v2 in nv
steps.
glEvalMesh2() applies this grid to all enabled
evaluators:
void glEvalMesh2( GLenum mode,
GLint p1, GLint p2,
GLint q2, GLint q2 );
The only significant difference from
the one-dimensional versions of these two commands is that in glEvalMesh2(),
the mode parameter can be GL_FILL as well as GL_POINT or GL_LINE.
GL_FILL generates filled polygons using the quad-mesh primitive.