glMapGrid1d(3)

NAME

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

C SPECIFICATION

       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 )

       delim $$

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]
           (glMapGrid2 only).

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

DESCRIPTION

       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.

ERRORS

       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.

ASSOCIATED GETS

       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

SEE ALSO

       glEvalCoord(3G),     glEvalMesh(3G),    glEvalPoint(3G),    glMap1(3G),
       glMap2(3G)

                                                                 GLMAPGRID(3G)