Hi eric, the one thing that I'm not sure about with the method of putting in a radius value and then having that control the corner formed at the previous point is what to do when a polyline is closed, since that then basically forms 2 corners in one point pick.

Would it work if the entered in radius was a global value used for every corner of the polyline? Or do you need to put in different radius values for each individual corner?

- Michael

Yes, they need to be different. Think of a straight line and then a tangential curve to another point (located by the mouse) and then a tangential straight line again (and on and on until finished but not necessarily closed.
eric

Hi eric,

> Think of a straight line and then a tangential curve to another point (located by the mouse)
> and then a tangential straight line again

Yeah but with the method you're describing here (arc tangent to previous segment and to a specific point) fully defines the arc and results in a particular radius being used which is calculated for you.

If you want to specify the radius, it would be a bit different than that, instead of picking the end point of the arc you would be picking the end points of all the "corner points" same as you do for a regular polyline, but the corner formed at the previous picked point would get replaced with an arc just as if you had filleted it.


Is the method you are talking about here "tangent curve to another point located by the mouse" specifically something you need like do you need to end a polyline with an arc piece at the very end of it? Or would having the equivalent of fillets at corners of the polylines work ok for what you need?

- Michael

Hi Michael ..

Here is an example ...

This was done with straight line segments and then filleted with various radii. I could have done the same thing with tangential arcs.

But if I could draw the first segment and then toggle for a tangential arc the end of it would be tangential and end wherever I place the next point ... with the end point determining the radius automatically ... toggle again and that starts a straight line tangential to the arc ... another toggle at the end of the straight line and the beginning of a new arc, etc.

This would allow the freedom to create almost any not predetermined arc just the same way that the arc tangential to two lines allows a variety of radii without having to pre decide the radius as in the fillet command.

I hope I am making myself clear. The object is to create a path or road center line that wanders gracefully through a land form. Existing methods work just fine but require more work than a simple toggle approach. (I don't mean that the toggle method is simple to create).

cheers,
eric

Hi Eric,

Is this what your talking about?



-

Hi eric,

> But if I could draw the first segment and then toggle for a tangential arc the end of it
> would be tangential and end wherever I place the next point ... with the end point
> determining the radius automatically ...

The main thing I don't like about this method is having the radius calculated as a side effect of the end point placement rather than having the radius specified directly.

I mean how often does it happen where you want to make something with lines and arcs but you care more about placing the endpoint of the arc rather than its radius? Not that it doesn't happen sometime but I have to kind of have to try and weigh how frequently that's going to happen.

You can already get very close to what you're describing using a combo of the Line command and the ArcContinue command (ArcContinue, not ArcTangent). Try this - set up keyboard shortcuts for 2 keys next to each other (like the a and s keys), one with the command Line on it and the other with the command ArcContinue on it.

Then you can basically do the kind of toggle that you're asking for by switching between those 2 keys - press a then draw a line, then press s (to run ArcContinue) and draw the arc, with ArcContinue you can draw an arc with 2 point picks, the first pick at the end of the line you just finished, and then the second pick for the end of the arc just like you're asking about. Then press a and draw a line snapped on to the end of the arc, etc...

ArcContinue will track to a mouse point and figure the radius for you so you don't need to predetermine a radius value for it. It doesn't go between 2 lines, it goes at the end of just one line.

I'm just not sure though that this kind of "meandering lines and arcs with non-specified radius values" should really be what a built in arc mechanism in polyline should focus on doing as its primary purpose....


Possibly it's a better idea overall to just a make it easier to chain together the regular commands, like having some option which could be activated by keyboard shortcut for automatically picking up the last drawn point from the previously used drawing command, so that when you triggered ArcContinue you wouldn't have to pick the first point for it...

- Michael

Hi Danny, one thing I sort of worry about with stuff like that is getting the whole screen sort of locked up with assistive or predictive things that you can no longer just freely place points anywhere you want, although it's more of a worry for freeform curve drawing than line and arc drawing.

But still what you show there seems to be cycling through quite a few different possibilities flashing on screen and that can bring a certain kind of learning curve needed to figure out how to control it... I can certainly see how it can be useful but there can be a fair amount of complexity that goes along with it too.

- Michael

Hi Michael,

I understand completely, I put this example up to clarify if this is what Eric meant.

I like the idea of setting up shortcut keys for Line and ArcContinue like you mentioned above, it would be nice when drawing a polyline to trigger the ArcContinue, in NX to get an arc you click/hold/drag, however I only see it for arbitrary drawing it would be difficult to get any accurate radii, as you said Michael 'seems to be cycling through quite a few different possibilities flashing on screen' and if you're not used to it, it can be quite daunting for the new user.

-

Hi Michael and all ...

Now I do feel a little ignorant. I do so much architectural work ... mostly straight lines of one kind or another so I have not really explored arc's much at all ... mostly using fillet when I need to.

Now I see, thanks to your questions and suggestions, that indeed I can do what I am asking for already. I just happen to be doing some fairly large land development work in preliminary stages at the moment and wanted to be freer with walk and road layouts but not as loose as freeform lines. I took your suggestion and now can toggle between lines and continuingarcs very freely.

Thank you ... these do not have to be built in some sort of complex command series ... the hot key system works great.

cheers,
eric

Hi eric, I'm glad that setting up the 2 shortcut keys with ArcContinue is close to what you were looking for!

I do want to streamline this process of chaining together different draw tools some more in the future as well. In v4 I hope to spend at least some time on curve tools.

- Michael