Hi,
I want to programatically draw a circle, at a given point along a line (or spline), so that the circle is perpendicular to the line at that point.
So, almost like extruding a shape along a linear element, where the shape (a planar shape) has to be placed perpendicular to the linear element.
Been looking what methods are available, but cant find one that makes any sense.
BTW - doing this in C# .net, so been looking at the VBA help.
Thanks!
Math basics or misunderstanding ?
Each tangent of a circle is perpendicular to it's radius. There is no other given thing for a circle.
So if your center(point) is outside the line, each circle that has a radius of the minimum distance between the center and the line is perpendicular (or almost not, because there are countless other tangents :) ).
It might be a good idea to draw an example of what you mean.
Hi Michael,
Misunderstanding i think. Sorry i didnt post a picture - an isometric view below:
The blue line is the target line, in this case, simply a vertical line. The circle is now dead centre on the line, and it's radii are
perpendicular to the line, at the insertion point. I know there is a term for the perpendicular vector, but it has escaped me.
So, what i want is, for whatever modification i make to the blue line (move its start/end points), i want that circle to remain fixed as it is currently to the line.
Someone who's working in 3D :-)
OK, that makes it clearer. I currently have some code in mdl on my computer in the company that aligns a normal (from polygon or similar) with a line. This should work here even.
I'll be back on Monday, but you might need someone else for the C# part :)
Michael
The PlanarElement interface provides what you want. A circle is a closed element that supports that interface. PlanarElement.Normal yields a normal vector as a Point3d. Use methods that act on Point3d data to create a set of vertices, then create your LineElement from those vertices.
Regards, Jon Summers LA Solutions
John, if I understand your needs, you want to create that circle and not that line, so it think you want to look into example about frenet frame.
Dan
Hi Dan, yep, thats exactly what i want to do. Im not too worried about the line, its just the circle or planar element.
Frenet frame? MS example or should i google it?
Thanks Jon, I will take a look at PlanarElement, see if that offers any solutions.