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)