How to get the direction of ellipse?
 

Hi,

How to get the direction of ellipse? Is the default direction as counter clockwise for ellipse?

I found that start point and end point were not specified by counter clockwise rule (the direction of rotation from start point to end point) when I get start point and end point of ellipse.

I cannot get the direction of partial ellipse according to the following code.

Code:

// get the ellipse data

LPDISPATCH dStartPnt = swSketchEllipse.GetStartPoint2();

LPDISPATCH dEndPnt = swSketchEllipse.GetEndPoint2();

LPDISPATCH dCenterPnt = swSketchEllipse.GetCenterPoint2();

LPDISPATCH dMajorPnt = swSketchEllipse.GetMajorPoint2();

LPDISPATCH dMinorPnt = swSketchEllipse.GetMinorPoint2();

yanhua

回复: How to get the direction of ellipse?
 

The start point position is incorrect when partial ellipse is drawn with clockwise in SolidWorks. Because the start point do not specified by counter clockwise rule. By now, I think that this is a bug of partial ellipse if I can not get the direction of ellipse.

You provide two parameters as start point and end point which do not specified by counter clockwise rule at all. If I draw partial ellipse with clockwise in SolidWorks, I only get the start point with clockwise via SW API. In other words, I get the incorrect result for the start point via SolidWorks API. If you do not tell the direction of partial ellipse, I expect to get the start point specified by the constant rule as counter clockwise in all situcations.

yanhua

回复: How to get the direction of ellipse?
 

Dear Yanhua,

In 2007 there is a new method, SketchEllipse::GetRotationDir, to get the direction. If you're using 2006 or later, the information below may help:

The direction of an arc is usually defined by looking in the opposite direction along this normal, going in a CCW direction from start to end point.

> Suppose, we have an arc with start angle 10 degree and end angle = 100 degree.
> Now for this arc if the direction is Counter clock wise then Arc angle
> is 90 degree and if the arc is clockwise the arc angle is 270 degree.

Regards,
Robin Richter