gleTwistExtrusion
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## Name

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

## C Specification

`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`[]);`

## Python Specification

``gleTwistExtrusion`` | `(` | ``contour`[][2], `cont_normal`[][2], `up`[3], `point_array`[][3], `color_array`[][3], `twist_array`[]) → `None``

## Parameters

`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

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