glGetMapdv(3)

NAME

       glGetMapdv, glGetMapfv, glGetMapiv - return evaluator parameters

C SPECIFICATION

       void glGetMapdv( GLenum target,
                        GLenum query,
                        GLdouble *v )
       void glGetMapfv( GLenum target,
                        GLenum query,
                        GLfloat *v )
       void glGetMapiv( GLenum target,
                        GLenum query,
                        GLint *v )

       delim $$

PARAMETERS

       target  Specifies  the  symbolic  name  of  a map.  Accepted values are
               GL_MAP1_COLOR_4,         GL_MAP1_INDEX,         GL_MAP1_NORMAL,
               GL_MAP1_TEXTURE_COORD_1,               GL_MAP1_TEXTURE_COORD_2,
               GL_MAP1_TEXTURE_COORD_3,               GL_MAP1_TEXTURE_COORD_4,
               GL_MAP1_VERTEX_3,       GL_MAP1_VERTEX_4,      GL_MAP2_COLOR_4,
               GL_MAP2_INDEX,     GL_MAP2_NORMAL,     GL_MAP2_TEXTURE_COORD_1,
               GL_MAP2_TEXTURE_COORD_2,               GL_MAP2_TEXTURE_COORD_3,
               GL_MAP2_TEXTURE_COORD_4,         GL_MAP2_VERTEX_3,          and
               GL_MAP2_VERTEX_4.

       query   Specifies  which parameter to return.  Symbolic names GL_COEFF,
               GL_ORDER, and GL_DOMAIN are accepted.

       v       Returns the requested data.

DESCRIPTION

       glMap1 and glMap2 define evaluators.  glGetMap returns evaluator param-
       eters.  target chooses a map, query selects a specific parameter, and v
       points to storage where the values will be returned.

       The acceptable values for the target parameter  are  described  in  the
       glMap1 and glMap2 reference pages.

       query can assume the following values:

       GL_COEFF       v returns the control points for the evaluator function.
                      One-dimensional  evaluators   return   $order$   control
                      points,  and  two-dimensional  evaluators return $uorder
                      ~times~ vorder$ control points.  Each control point con-
                      sists of one, two, three, or four integer, single-preci-
                      sion floating-point, or double-precision  floating-point
                      values,  depending on the type of the evaluator.  The GL
                      returns  two-dimensional  control  points  in  row-major
                      order,  incrementing  the $uorder$ index quickly and the
                      $vorder$ index after each  row.   Integer  values,  when
                      requested,  are computed by rounding the internal float-
                      ing-point values to the nearest integer values.

       GL_ORDER       v returns the order of  the  evaluator  function.   One-
                      dimensional  evaluators  return a single value, $order$.
                      The initial  value  is  1.   Two-dimensional  evaluators
                      return  two  values,  $uorder$ and $vorder$. The initial
                      value is 1,1.

       GL_DOMAIN      v returns the linear $u$  and  $v$  mapping  parameters.
                      One-dimensional  evaluators  return two values, $u1$ and
                      $u2$, as specified by glMap1.   Two-dimensional  evalua-
                      tors  return four values ($u1$, $u2$, $v1$, and $v2$) as
                      specified by glMap2.  Integer  values,  when  requested,
                      are  computed  by  rounding  the internal floating-point
                      values to the nearest integer values.

NOTES

       If an error is generated, no change is made to the contents of v.

ERRORS

       GL_INVALID_ENUM is generated if  either  target  or  query  is  not  an
       accepted value.

       GL_INVALID_OPERATION  is  generated if glGetMap is executed between the
       execution of glBegin and the corresponding execution of glEnd.

SEE ALSO

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

                                                                  GLGETMAP(3G)