- return evaluator parameters



C SPECIFICATION


PARAMETERS

       _param1  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.

       _param2  Specifies which parameter  to  return.   Symbolic
                names   GL_COEFF,  GL_ORDER,  and  GL_DOMAIN  are
                accepted.

       _param3  Returns the requested data.


DESCRIPTION

       glMap1 and glMap2  define  evaluators.   glGetMap  returns
       evaluator  parameters.   _param1  chooses  a  map, _param2
       selects a specific parameter, and _param3 points to  stor-
       age where the values will be returned.

       The  acceptable  values  for  the  _param1  parameter  are
       described in the glMap1 and glMap2 reference pages.

       _param2 can assume the following values:

       GL_COEFF       _param3 returns the control points for  the
                      evaluator function.  One-dimensional evalu-
                      ators return order control points, and two-
                      dimensional evaluators return uorderxvorder
                      control points.  Each  control  point  con-
                      sists  of one, two, three, or four integer,
                      single-precision 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
                      floating-point values to the nearest  inte-
                      ger values.

       GL_ORDER       _param3  returns the order of the evaluator
                      function.     One-dimensional    evaluators


NOTES

       If an error is generated, no change is made  to  the  con-
       tents of _param3.


ERRORS

       GL_INVALID_ENUM  is generated if either _param1 or _param2
       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, glMap1, glMap2



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