---
name: "gleLathe"
section: "3gle"
platform: "linux"
package: "libgle3-dev"
version: "3.1.2-1+b2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/gleLathe"
---

# gleLathe(3gle)

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

## 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)