.\"
.\" GLE Tubing & Extrusions Library Documentation 
.\"
.TH gleLathe 3GLE "3.0" "GLE" "GLE"
.SH NAME
gleLathe - Sweep using a Z-axis shear to create an arbitrary contour along a helical path.
.SH SYNTAX
.nf
.LP
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 */
.fi
.SH ARGUMENTS
.IP \fIncp\fP 1i
number of contour points
.IP \fIcontour\fP 1i
2D contour
.IP \fIcont_normal\fP 1i
2D contour normals
.IP \fIup\fP 1i
up vector for contour
.IP \fIstartRadius\fP 1i
spiral starts in x-y plane
.IP \fIdrdTheta\fP 1i
change in radius per revolution
.IP \fIstartZ\fP 1i
starting z value
.IP \fIdzdTheta\fP 1i
change in Z per revolution
.IP \fIstartXform\fP 1i
starting contour affine transformation
.IP \fIdXformdTheta\fP 1i
tangent change xform per revolution
.IP \fIstartTheta\fP 1i
start angle in x-y plane
.IP \fIsweepTheta\fP 1i
degrees to spiral around
.SH 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.

.SH SEE ALSO
gleSpiral
.SH AUTHOR
Linas Vepstas (linas@linas.org)