> You may be be able to buy Adobe someday, hehe. And Corel. Or Newtek. ;-)

:) :) Well, I think I'll be pretty happy if I can just manage to survive as my own small business...

- Michael

Don't dream : google will buy all softs for put them on Google Earth :D

Ok, one thing I've been working on for the last day or so is a new "Tangent preserving sweep" mechanism.

This is a special mode for sweep which can kick in if you have all planar profiles, and all profiles share a common tangent direction. In this case the sweep is done in a different way such that the resulting surface maintains the common tangent direction of the profiles.

In a normal sweep the profiles get disturbed due to their rotation as they slide along the rails, if the rails are not symmetrical mirror images of one another.

Here is an image to show the results - these are half surfaces mirrored over with the center edge hidden. The standard sweep is on the left, the new Tangent preserving sweep on the right.



Surface quality seems amazingly good, except for a small subtle bump right near the pole, I'm going to see if I can do something about that.

I was also thinking of calling this a "mouse buttocks removal" sweep... :)

- Michael

This will be a great addition, thanks. I would also like to toss in a vote for the 3-rail sweep method Tyglik posted an image of. I find that the more profile shapes I add to my sweep the chances increase that I will end up up with what looks like a "wrinkle" appearing between profiles after the sweep is completed. Also, I generally have to draw the third rail anyway as a guide to create my profiles, so it would save a lot of time to just be able to use it in the sweep.

Well, I was able to reduce the size of the bump in the new tangent preserving sweep when it collapses down to a point, but I was not able to completely remove it. It is a pretty tiny bump so I think for many purposes it is ok, but it does mess up stuff like shelling and offsets. I'm still going to keep this new tangent preserving mode as an option because it will work nicely for certain situations, and there isn't any bump in situations where the rails don't collapse down to a point.

Joe wrote:
> I would also like to toss in a vote for the 3-rail sweep method Tyglik posted an image of.

Yup, I'm working on this next. So far I've got it working with one-rail sweep, here is an example.
Regular one-rail sweep:



One-rail sweep with new scaling curve set:



Basically this allows you to have another curve drawn which gives a scale factor to the sweep profile as it moves along the main sweep rail. This can be nice because previously to get this type of a shape you would have to make a whole bunch of different sized cross-sections for the sweep. It is a lot easier to have one additional guide curve to control this type of thing instead.

It should be pretty similar for 2-rail sweep - that's next.

- Michael

> What append when the internal curve auto intersect itself due
> the angle too hard?
> It's like filet : nothing is calculated or form is drawn in any case?

This one should create the surface anyway (just like current one-rail sweep), but the result will of course be messy with a self-intersecting surface.

Here's another example. Some pretty elegant results are possible from just 3 definition curves!



- Michael

Yes, that is what I was hoping for! In the current version I have to create a bunch of profiles and experiment with their placement until I get a smooth result. This feature will make for a much faster workflow with better results.

Of course I suppose than you can modify the form result by the history of the start curves ?

I suppose also than the 3 curves can be open?

And for the next versions when you will have 4 curves that will be a little like coons curve?

Ps What is the name of this "one sweep" with special scale rails?

Hi Michael,

Someone had developed a script for Rhino3 that did this operation, but it's nice to have it as a "built in" feature
so that it's accessible to everyone rather than the just the scripting gurus and the users that collect their scripts! ;-)

Jesse

Hi Pilou,

> Of course I suppose than you can modify the form result by the history of the start curves ?

Yes!


> And for the next versions when you will have 4 curves that will be a little like coons curve?

Well, that would be like the already existing 2-rail sweep. But Coons patch is a little different than 2-rail sweep. I'm hoping to squeeze that in for the beta after this next one.


> Ps What is the name of this "one sweep" with special scale rails?

It's still the sweep command, there is a new "Pick scaling curve" option inside of sweep.

So I guess the name would be "Sweep with scaling curve".

- Michael

> Someone had developed a script for Rhino3 that did this operation, but it's nice
> to have it as a "built in" feature so that it's accessible to everyone rather than the
> just the scripting gurus and the users that collect their scripts! ;-)

Hi Jesse - yup definitely accessibility is better from having it built in. But also having it built in makes it possible to tweak the curves and have it update with history.

Usually an operation that is generated through a bunch of script is not as history friendly.

- Michael

So cool sweet sweeps :)

Very nice Michael. MoI is already worth the price of admission and yet you just keep adding more goodies.

Looking forward to the next beta.

> I suppose also than the 3 curves can be open?

Any of the curves can be open, but the scaling curve won't have any effect if you have an open profile curve and the profiles are on the opposite side of the rail from the scaling curve.

Ok, additional scaling control is looking good for 2-rail sweeps now as well.

Here is an example from earlier in this thread where attempting to control the mouse shape by inserting more profiles caused a lumpy result:



This tends to be common when adding in a lot more profiles. There is just a lot of stuff happening, the rails are contributing one part to the scaling and then the morphing from one profile to another is another factor. It can be hard to control the resulting shape with all this stuff going on.

Now with the new scaling curve it allows more control over the stretching of the profiles. This is the result with the new scaling curve applied:



In fact in this case we could just use one profile and the scaling curve, the multiple profiles are no longer necessary just for attempting to get control over the height.

So I think these 2 new options (tangent preserving for half-shapes, and scaling curve) should help juice up sweep another couple of notches.

- Michael

Hi Pilou, here is some additional explanation.

Here is the setup for a normal 2-rail sweep:



The 2 rails are flat on the plane (one of the 2 rails is shown selected here), and the profile is sticking up vertically.

You can create a sweep from these curves, by selecting the profile and running Construct / Sweep, then selecting the rails. That will generate this surface (seen from the side here):



There is nothing terrible about this surface, but if you don't like the shape of the sweep as viewed from the side, it is difficult to change this in the current beta. In the next beta, the scaling curve option will give you an additional tool to control the shape as viewed from the side. This shows the side-profile scaling curve (shown here as the selected curve):



In the next beta, this curve can be applied to the sweep by clicking a new "Pick scaling curve" option that shows up along with the other sweep parameters. In this case applying the scaling curve (which should generally run down the center line of the sweep) will update the sweep to have this result, viewed from the side again:



The scaling curve is shown selected there. You can see that this has changed shape from the original sweep shown above - the sweep profiles (vertical sections) have been stretched to match up with the scaling curve. So now the side-view of the sweep has been adapted to have the same type of shape as the scaling curve.

Previously making this kind of an edit would have been difficult, you would have to try to put in a lot of vertical profiles to try and gain more control over the shape in the side view. But even as you added more profiles you would tend to get bumps. This new method does not not cause bumps.

So this helps you gain additional control over the shape of the sweep - it mostly adds control over the shape as viewed from the side-view.

Does that make more sense?

You might think of it as a kind of optional 3rd rail that can run down the center of a 2-rail sweep to provide additional control.

- Michael