Home Page > KernelCAD Components > Interfaces > Sections > IObjectPosition_KC

IObjectPosition_KC Interface

FindStableTangentialPlane

The interface calculates position and orientation of a 3D plane  which is tangential to the surface of the obejct at least at three isolated points. From different prospective the method calculates which its side can be used to put it into a stable position on a flat surface. IObjectPosition_KC can be queried from ISection interface

HRESULT FindStableTangentialPlane(DIPoint* pt0, DIPoint* pt1, DIPoint* pt2, double distMax, int* result )

Parameters

pt0, pt1, pt2 - [in,out] Points in global coordinates close to the surface which will be modified to identify a stable tangential plane

distMax- [in] maximal distance from the initial point or 0 if no restriction required. See remarks.

result - [out] - The return code: > 0 means success. Any other return values mean thet there was an error

Return value codes:

2 Solution found, but was restricted by distMax for one or more points

1 Success

0  Unknown internal error

-1 Could not calculate projection to the surface of starting points. Can be caused by incorrect type of section or incorrect initial position relative to surface geometry

-2 The initial points were collinear or have become collinear during the calcualtion

-3 a point reached edge of the surface

-4 At least two points converged into one

-5 Infinite loop. Solution can not be achieved

Remarks

Assuming pt0, pt1 and pt2 points are close to the surface of this object (the object this interface was queried from) and do not lie on the same line the method modifies position of the points in such way that they define a stable plane. Stable plane is tangential to the surface of the obejct at least at three different non-collinear points and the object lies completely on one side of the plane, namely on the negative side.

ppt0, pt1 and pt2 are also assumed to be arranged in CCW direction looking from outside of the object or more correctly from end of normal to the surface.

NNotice that not every starting configuration pt0, pt1, pt2 results in a stable plane. The points have to be relatively close to three isolated locally concave areas on the surface. The algorithm returns an error (result<=0) if during execution a point reached edge of the surface or two or more points converged.

If i>distMax>0 modifications of all three points are restricted to area of the surface not further than distMax from the initial point. Set distMax to 0 to avoid the restriction, which is the default recommended behaiviour. If distMax>0 and one or more points were restricted the returned result value is 2.

Use error codes above or IError_KC to obtain description of the error if the returned result is less or equal to 0.

Completely convex objects do not have a stable tangential plane. Point set for such an object will either return an error indicating converged points or will converge to corners of a single simplex for meshed surfaces./p>