glMapGrid1d, glMapGrid1f, glMapGrid2d, glMapGrid2f - define
a one- or two-dimensional mesh

glMapGrid1d
	glMapGrid1d(un, u1, u2) -> None
glMapGrid1f
	glMapGrid1f(un, u1, u2) -> None
glMapGrid2d
	glMapGrid2d(un, u1, u2, vn, v1, v2) -> None
glMapGrid2f
	glMapGrid2f(un, u1, u2, vn, v1, v2) -> None

void glMapGrid1d( GLint un,
                  GLdouble u1,
                  GLdouble u2	)
void glMapGrid1f( GLint un,
                  GLfloat u1,
                  GLfloat u2 )
void glMapGrid2d( GLint un,
                  GLdouble u1,
                  GLdouble u2,
                  GLint vn,
                  GLdouble v1,
                  GLdouble v2	)
void glMapGrid2f( GLint un,
                  GLfloat u1,
                  GLfloat u2,
                  GLint vn,
                  GLfloat v1,
                  GLfloat v2 )

un  Specifies	the number of partitions in the	grid range
    interval [u1, u2].  Must be positive.

u1, u2
    Specify the mappings for integer grid domain values i=0
    and i=un.

vn  Specifies	the number of partitions in the	grid range
    interval [v1, v2]
    (glMapGrid2 only).

v1, v2
    Specify the mappings for integer grid domain values j=0
    and j=vn
    (glMapGrid2 only).

glMapGrid and	glEvalMesh are used together to	efficiently
generate and evaluate	a series of evenly-spaced map domain
values.  glEvalMesh steps through the	integer	domain of a
one- or two-dimensional grid,	whose range is the domain of
the evaluation maps specified	by glMap1 and glMap2.

glMapGrid1 and glMapGrid2 specify the	linear grid mappings
between the i	(or i and j) integer grid coordinates, to the
u (or	u and v) floating-point	evaluation map coordinates.
See glMap1 and glMap2	for details of how u and v coordinates
are evaluated.

glMapGrid1 specifies a single	linear mapping such that
integer grid coordinate 0 maps exactly to u1,	and integer
grid coordinate un maps exactly to u2.  All other integer
grid coordinates i are mapped	so that

                    u	= i(u2-u1)/un +	u1

glMapGrid2 specifies two such	linear mappings.  One maps
integer grid coordinate i=0 exactly to u1, and integer grid
coordinate i=un exactly to u2.  The other maps integer grid
coordinate j=0 exactly to v1,	and integer grid coordinate
j=vn exactly to v2.  Other integer grid coordinates i	and j
are mapped such that

                    u	= i(u2-u1)/un +	u1

                    v	= j(v2-v1)/vn +	v1

The mappings specified by glMapGrid are used identically by
glEvalMesh and glEvalPoint.

GL_INVALID_VALUE is generated	if either un or	vn is not
positive.

GL_INVALID_OPERATION is generated if glMapGrid is executed
between the execution	of glBegin and the corresponding
execution of glEnd.

glGet	with argument GL_MAP1_GRID_DOMAIN
glGet	with argument GL_MAP2_GRID_DOMAIN
glGet	with argument GL_MAP1_GRID_SEGMENTS
glGet	with argument GL_MAP2_GRID_SEGMENTS

glEvalCoord, glEvalMesh, glEvalPoint,	glMap1,	glMap2