bs3_curve_tangent_cone

List of:	Functions
Subjects:	Construction Geometry, Spline Interface
Contents:	Kernel

Action:

Creates a cone bounding the tangent directions of a curve.

Prototype:

bs3_curve_tancone bs3_curve_tangent_cone (

bs3_curve cur,

// given curve

logical approx_OK

// make a quick

= FALSE

// approximation

);

Includes:

#include "kernel/acis.hxx"

#include "baseutil/logical.h"

#include "kernel/spline/bs3_crv/bs3curve.hxx"

#include "kernel/spline/bs3_crv/sp3crtn.hxx"

Description:

A tangent cone is a cone that contains all the tangent vectors of a curve. If the curve is a straight line, the cone would be directed along the line and having a very small angle would contain all the tangent vectors of the line; in fact, the angle could be 0. All the tangent go in the same direction. If the curve was almost a straight line, the cone axis could approximate the direction of the curve somehow, and the cone's angle would need to be a little bigger. The more the curve curves, the bigger the cone angle. If the curve were a complete circle, the cone would need to encompass every direction (even though it lies in a plane), so the cone's half angle would be pi. If the curve were a helix, the cone's half angle would be slightly less than pi/2, depending on the pitch and radius of the helix.

If the logical approx argument is TRUE, a quick approximation is found. The resulting cone is guaranteed to be wholly within the one found with a FALSE argument, but is not guaranteed to be a true bound - the curve tangent could lie outside it at some parts of the curve.

Library:

kernel

Filename:

kern/kernel/spline/bs3_crv/sp3crtn.hxx

Effect:

System routine

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