NAME

       gleTwistExtrusion - Extrude arbitrary 2D contour along arbitrary 3D path, specifying local
       rotations (twists).

SYNTAX

       void gleTwistExtrusion (int ncp,
                       gleDouble contour[][2],
                       gleDouble cont_normal[][2],
                       gleDouble up[3],
                       int npoints,
                       gleDouble point_array[][3],
                       float color_array[][3],
                       gleDouble twist_array[]);

ARGUMENTS

       ncp       number of contour points

       contour   2D contour

       cont_normal
                 2D contour normals

       up        up vector for contour

       npoints   numpoints in poly-line

       point_array
                 polyline vertices

       color_array
                 colors at polyline verts

       twist_array
                 contour twists (in degrees)

DESCRIPTION

       Extrude arbitrary 2D contour along arbitrary 3D path, specifying local rotations (twists).
       As  the  contour  is  extruded,  it  will  be twisted by the amount specified in the array
       "twist_array". The angles are measured in degrees, and the rotation is about the origin of
       the contour coordinate system.

       The  argument  "contour"  specifies  the  2D  contour  to  be extruded, while the argument
       "point_array" specifies the path along which to extrude.   The  vector  "up"  defines  the
       orientation of the contour y-axis in real 3D space.

       Note  that  neither the very first segment, nor the very last segment are drawn. The first
       and last segments serve only to define the angle of the join  at  the  very  ends  of  the
       polyline.  Thus,  to draw one segment, three must be specified. To draw two segments, four
       must be specified, etc.

       The normal array may be  NULL.  If  it  is,  normal  vectors  will  NOT  be  automatically
       generated, and the object will look terrible when lit.

       The  color  array  may  be  NULL.  If  NULL,  the  current color is used. If not NULL, the
       glColor3f() routine is used to set the color; therefore, specifying the  glColorMaterial()
       subroutine  before  this  primitive  can  be  used to set diffuse, specular, ambient, etc.
       colors.

SEE ALSO

       gleExtrusion, gleSuperExtrusion

AUTHOR

       Linas Vepstas (linas@linas.org)