glMapGrid(3G)

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 )


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 in tandem 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 such 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, glEvalMesh, glEvalPoint, glMap1, glMap2