I will post about this again.

A simple 2 rail sweep of a rectangle on 2 Int splines

01: the rectangle and 2 rails
02: the result. Unacceptable.
03: I moved one of the rails to to top corner.
04/05: the result, again Unacceptable

I did have maintain height set.

No, it is not drawing artifacts, it is a bad sweep. What sections?
It is a simple example. I am using splines because they give better results.

I have made another similar example, but have used 2 trimmed Ellipse:-

01: the cross section (a rectangle) and 2 trimmed ellipse for rails
02: the result
03 the model exported into another app


EDIT:

Does the mac version not have these problems?

.

Hi Steve,
I have not used 2-rail sweeps until now, so I thought I would have a go, to both learn something, and see if your problems repeat for me.
I tried to 2-rail sweep a rectangle (form the rectangle tool), along two parallel arcs. In the first instance, I could not select the rectangle as the shape to sweep. When I redrew the rectangle as 4 distinct lines, then I could select them. They swept ok. I then tried using interp splines as the rails, and managed to get two splines, non-parallel, with different number of control points in each, and the sweep worked fine for me, although it had a lot of height variations. I re-did it selecting option for maintain height, and got what I thought I should have got, so I have to say from my brief effort, there seems to be no problem when doing 2-rail sweeps on a mac. I run Leopard 10.5.7, and vc2d3d build 786.
Regards, Ian.

Hi Ian,

Thanks for checking this on the Mac.

Attached is a file with a rectangle(grouped lines) and 2 trimmed Ellipse for rails, with the result of a solid sweep.

Changing the Rails to different Types (B-spline/Int spline) does change the result, but it should be more consistent as changing the type does bring its own problems with the spline moving.



- Steve

Hi Steve,
I only have vc2d3d, and while I can open your file, I can do nothing with it. Can you post just the original (rectangular?) shape, and the original rails, please?
I actually had a problem after my last post. I moved just two random points on one of the splines, and the sweep failed, saying "self intersecting or cusping surface found", about which I have no idea! Subsequent attempts have led to similar failures, so I must assume that my first spline just happened to fall inside some degree of acceptability to the process, but I have no clue how to do this deliberately. I will keep trying, not because I use them, just to rise to the challenge - if in fact I can!!
Regards, Ian.

Further to this. If the two rails are not parallel then there are no problems.

So the rule is -- If you want a swept solid with parallel faces, use a one rail sweep, otherwise use a two rail sweep.

Hi Ian,


Regards,

- Steve

Okay, this time it worked. I started from scratch, drew two random int. splines in x-y plane, with different number of control points. Drew a rectangle of 4 lines in x-z plane, using the initial ends of the splines as one side of the rectangle. Selected 2-rail sweep, followed the instructions, and got a mostly predictable result. The swept solid did not go to the end of either spline, seeming to stop one point short; I have no idea why it stopped where it did. I have almost zero experience with splines, so if anyone can explain what is happening, simply, I would be happy to read that.
:o
Regards, Ian.

Sorry, that will be due to my having the color of the lines/splines set to white.
Select the lines/splines and change the color.


- Steve

Maybe I should stay away from splines altogether!
While 'playing' with the splines I was using as rails, when I try to select a control point I am asked to choose between the solid and a B-spline. I thought I had drawn interpolate splines! ie, I used the Interploate Spline tool to draw them!
Perhaps I should ask, what differentiates Interpolate, Control Point and Bezier splines as drawing entities?
Secondly, a line has magically appeared which has become part of my solid, and defines a new shape of the solid. See pics 4,5. It looks not unlike one of Steve's trimmed ellipses, and the solid has taken up the shape indicated by the new line. It highlights when I select the solid, and the whole solid highlights when I select the line. The original spline is still there, but is simply ignored by the solid.
I'm really getting confused now!:(
Steve, thanks for the hint about the white lines. No wonder I was having a hard time seeing them!!:rolleyes: I was successful in creating the solid from your geometry, see thumbnail below. It went cleanly following the normal steps, and looks correct, so, back to an early post, it seems to be ok on a mac.:)

Regards, Ian.