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GLMAPGRID(3G)                                                                                  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 together to efficiently generate and evaluate a series of evenly-spaced evenlyspaced
       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)