NAME
	  fglMapGrid1d,	fglMapGrid1f, fglMapGrid2d, fglMapGrid2f -
	  define a one-	or two-dimensional mesh


     FORTRAN SPECIFICATION
	  SUBROUTINE fglMapGrid1d( INTEGER*4 un,
				   REAL*8 u1,
				   REAL*8 u2 )
	  SUBROUTINE fglMapGrid1f( INTEGER*4 un,
				   REAL*4 u1,
				   REAL*4 u2 )
	  SUBROUTINE fglMapGrid2d( INTEGER*4 un,
				   REAL*8 u1,
				   REAL*8 u2,
				   INTEGER*4 vn,
				   REAL*8 v1,
				   REAL*8 v2 )
	  SUBROUTINE fglMapGrid2f( INTEGER*4 un,
				   REAL*4 u1,
				   REAL*4 u2,
				   INTEGER*4 vn,
				   REAL*4 v1,
				   REAL*4 v2 )


     PARAMETERS
	  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]
	      (fglMapGrid2 only).

	  v1, v2
	      Specify the mappings for integer grid domain values j=0
	      and j=vn
	      (fglMapGrid2 only).

     DESCRIPTION
	  fglMapGrid and fglEvalMesh are used together to efficiently
	  generate and evaluate	a series of evenly-spaced map domain
	  values.  fglEvalMesh steps through the integer domain	of a
	  one- or two-dimensional grid,	whose range is the domain of
	  the evaluation maps specified	by fglMap1 and fglMap2.

	  fglMapGrid1 and fglMapGrid2 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 fglMap1 and fglMap2 for details of how u and v
	  coordinates are evaluated.

	  fglMapGrid1 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

	  fglMapGrid2 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 fglMapGrid are used	identically by
	  fglEvalMesh and fglEvalPoint.

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

	  GL_INVALID_OPERATION is generated if fglMapGrid is executed
	  between the execution	of fglBegin and	the corresponding
	  execution of fglEnd.

     ASSOCIATED	GETS
	  fglGet with argument GL_MAP1_GRID_DOMAIN
	  fglGet with argument GL_MAP2_GRID_DOMAIN
	  fglGet with argument GL_MAP1_GRID_SEGMENTS
	  fglGet with argument GL_MAP2_GRID_SEGMENTS

     SEE ALSO
	  fglEvalCoord,	fglEvalMesh, fglEvalPoint, fglMap1, fglMap2