NAME

       gleLathe - Sweep using a Z-axis shear to create an arbitrary contour along a helical path.

SYNTAX

       void gleLathe (int ncp,
                       gleDouble contour[][2],
                       gleDouble cont_normal[][2],
                       gleDouble up[3],
                       gleDouble startRadius,     /* spiral starts in x-y plane */
                       gleDouble drdTheta,        /* change in radius per revolution */
                       gleDouble startZ,          /* starting z value */
                       gleDouble dzdTheta,        /* change in Z per revolution */
                       gleDouble startXform[2][3], /* starting contour affine xform */
                       gleDouble dXformdTheta[2][3], /* tangent change xform per revoln */
                       gleDouble startTheta,      /* start angle in x-y plane */
                       gleDouble sweepTheta);     /* degrees to spiral around */

ARGUMENTS

       ncp       number of contour points

       contour   2D contour

       cont_normal
                 2D contour normals

       up        up vector for contour

       startRadius
                 spiral starts in x-y plane

       drdTheta  change in radius per revolution

       startZ    starting z value

       dzdTheta  change in Z per revolution

       startXform
                 starting contour affine transformation

       dXformdTheta
                 tangent change xform per revolution

       startTheta
                 start angle in x-y plane

       sweepTheta
                 degrees to spiral around

DESCRIPTION

       Sweep  an  arbitrary  contour along a helical path. The sweep will be performed as a shear
       along the z-axis, so that the  orientation  of  the  contour  is  displaced,  rather  than
       translated, as the contour is swept.

       The axis of the helix lies along the modeling coordinate z-axis.

       An  affine  transform can be applied as the contour is swept. For most ordinary usage, the
       affines should be given as NULL.

SEE ALSO

       gleSpiral

AUTHOR

       Linas Vepstas (linas@linas.org)