GLMAPGRID(3G)                                                    GLMAPGRID(3G)



NAME
       glapGrid1d,,  glapGrid1f,,  glapGrid2d,, glapGrid2f - define a one- or
       two-dimensional mesh


C SPECIFICATION
       void glapGrid1d( GLint un,
                         GLdouble u1,
                         GLdouble u2 )
       void glapGrid1f( GLint un,
                         GLfloat u1,
                         GLfloat u2 )
       void glapGrid2d( GLint un,
                         GLdouble u1,
                         GLdouble u2,
                         GLint vn,
                         GLdouble v1,
                         GLdouble v2 )
       void glapGrid2f( GLint un,
                         GLfloat u1,
                         GLfloat u2,
                         GLint vn,
                         GLfloat v1,
                         GLfloat 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]
           (glapGrid2 only).

       v1, v2
           Specify the mappings for integer grid domain values j=0 and j=vn
           (glapGrid2 only).

DESCRIPTION
       glapGrid and glEvalesh are used together to efficiently generate  and
       evaluate a series of evenly-spaced map domain values.  glEvalesh steps
       through the integer domain of a one-  or  two-dimensional  grid,  whose
       range  is  the  domain  of  the evaluation maps specified by glap1 and
       glap2.

       glapGrid1 and glapGrid2 specify the linear grid mappings between  the
       i  (or  i and j) integer grid coordinates, to the u (or u and v) float-
       ing-point evaluation  map  coordinates.   See  glap1  and  glap2  for
       details of how u and v coordinates are evaluated.

       glapGrid1  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

       glapGrid2 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 coordi-
       nates i and j are mapped such that


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

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


       The mappings specified by glapGrid are used identically by  glEvalesh
       and glEvalPoint.

ERORS
       GLINVALIDVALUE is generated if either un or vn is not positive.

       GLINVALIDOPERATION  is generated if glapGrid is executed between the
       execution of glBegin and the corresponding execution of glEnd.

ASOCIATED GETS
       glGet with argument GLMAP1GRIDOMAIN
       glGet with argument GLMAP2GRIDOMAIN
       glGet with argument GLMAP1GRIDSEGMENTS
       glGet with argument GLMAP2GRIDSEGMENTS

SEE ALSO
       glEvalCoord, glEvalesh, glEvalPoint, glap1, glap2



                                                                 GLMAPGRID(3G)