Hi Marc, the new patch here: http://moi3d.com/forum/index.php?webtag=MOI&msg=1013.24
now enables the Alt key override for temporarily disabling snapping.

The only thing is I'm not sure about disabling Grid Snap along with Straight Snap and Object Snap. It seems like it might be a good idea to leave Grid snap on if it was enabled, that way you would be able to use Alt+click as a shortcut for kind of reaching through objects and getting to the grid.

- Michael

Hi Michael,

Seems to be working flawlessly!

Right-click alone on the snap type work best and is simpler than using Alt.
I have also noticed right-clicking on one snap type even after adding one ore two extra modes turns them all on, this is great.

About leaving the Grid snap on, it could be a good in a grid-based drawing situation, when object snaps are in the way. But then again, if you're fixed on grid snap and want to fine-tune some curve points, the modifier becomes quite handy.

I guess depends on the type of work you do most, but I get the impression that removing all would be best.

Regards,

Marc

Hi,

Thanks again for the alt modifier, it's quite effective and I use it regularly.

I've observed that the tangent snap mode operate differently than the Tangent circle Function;
If I start a ordinary 3 points circle near a circle (with only tangent mode enabled), I can't seem to obtain a tangent point.

It makes it hard to construct a circle or an arc with only one tangent reference. (as it's fairly easy with two reference curves using Tangent circle Function)

The tangent snap mode appears to be working well with line.

There must be something I am missing!


Also, having the"start,end,on" option in 3pt circle (Like3pt arc) could be great.


Regards,

Marc

Hi Marc,

> I've observed that the tangent snap mode operate differently than the
> Tangent circle Function;
> If I start a ordinary 3 points circle near a circle (with only tangent mode
> enabled), I can't seem to obtain a tangent point.

Yes, this is kind of a long standing area of confusion in drawing circles.

The problem is that the tangent snap is only about placing a point tangent from the previous picked point - this is not the same thing as placing the generated circle to be tangent. The Tangent circle command on the other hand is focused on placing the generated circle and not just picked points.

Here is a visual example. Say you are drawing a circle with the "3 pts" tool, and you have finished picking the first 2 points and are currently in progress of picking the 3rd point like this:



If you move your mouse to the curve for the 3rd point, you will find a tangent snap there:



However, as you can see the circle is not tangent to the curve, what is tangent here is the line formed between the second point (that is the previous picked point) and the current point, here I have drawn the tangent line in red, you can see it goes directly through the point that was labeled "2" above:



That's all that tangent snap does, it finds a tangent to a curve from the previous picked point, it works the same if you are drawing a line, circle, curve, etc... It's always a tangent in a straight line from the previous picked point.

When you use the Circle tangent tool, it doesn't use the tangent snap anymore, it does a completely different calculation that is focused on making the generated circle tangent to the curves you picked on.


> It makes it hard to construct a circle or an arc with only one tangent reference.

Sometimes it is easiest to use perpendicular snap to generate tangent circles.

So for example if I want to create a circle through a given point tangent to the curve:



If you use the Circle Diam (By 2 diameter points) command, you can place the first point on that point away from the curve, and then for the second point use perp snap, that will create a circle tangent to the curve.



Similarly you can use the circle from center point - basically if you place the center of a circle along a perpendicular that is another way to create tangency.

If you have one that you are having problems with, can you please post the .3dm model file so I can take a look?


> Also, having the"start,end,on" option in 3pt circle (Like3pt arc) could be great.

Well, any 3 points will create the same circle shape regardless of the order you pick them in... For arcs it is a little different because the arc has a start and end point.

- Michael

Hi Michael,

Thanks for the clarification on the tangent's behavior in Moi, I'll experiment further more.
I imagine I can use the freeform tool more than I do presently, It seems to work pretty well and the fact that the align command works on control points is quite amazing.

I used to work quite a lot with Autocad in a previous life, so I thought tangent operated in a similar fashion while constructing circles.

I remember a small script I've written in Autocad, It was useful to trace sketches.

1. -The first point was picked on circle or arc (with the tangent snap constrain)
2. -Then it paused for user input for a second point. (which was the middle of three points)
3. -For the last point the tangent constrain was turn on again. If the user selected a point not passing through circle or arc, it canceled the constrain and the last point could be positioned anywhere.

The project I am currently working on is a sweeped violin fiddle head, I really enjoy doing those kinds of shapes with nurbs (and especially with Moi viewports).

I had a Dxf 2d reference but somehow I lost precision while translating the dxf to AI path, endpoints were not connected and stuff like that. I ended up retracing it with the freeform tool using the trough points.

Regards,

Marc

Hi Marc,

> I imagine I can use the freeform tool more than I do presently,

You mean for tracing an outline? Yes, that's probably generally your best bet. After a bit of practice you can get more used to how it works, you'll kind of place your points slightly to the outside of the thing you're tracing so that the actual curve that is sort of shrunken down a bit from those points will go along the trace line.

One thing that is good about that is that it makes it easier to create a single long very smooth piece. If you trace with arcs, you'll tend to get stuff that is split into more segments and you'll generally only get tangent smoothness instead of a higher degree of smoothness...


> I used to work quite a lot with Autocad in a previous life, so I thought tangent
> operated in a similar fashion while constructing circles.

It's been quite a while since I have messed around with Autocad, so I don't quite remember how that works. Was this one of the things that got handled specially if you typed in "tan" before picking the first point?

One thing that is a little different with MoI is that MoI only has the equivalent of a "running object snap", it doesn't really have any concept of a single-shot special object snap like that.

But I may be able to improve this in the future to work more like you expect.

This is one of those things that alters the location of the earlier picked points to true them up to tangent locations, is that right?

- Michael

Hi Michael,

Just for the record have managed to record different examples of tangent behavior.

This example is from SolidEdge, it's the tangent circle creation mode.
It's basically a "2pts on edge circle" with a fixed tangent 1rst point, is has a live dragging of the circle.

http://www.youtube.com/watch?v=7Obe3PcQSVw


This one from Autocad, it is a "3pts on edge circle", in this example: tan, point, point.

The reference circle is in white and in the background there is a gray shape to show an example of tracing situation.
This behaves in a different way as the tangent point will change depending on the two points picked afterwards. The results does not show after the 3rd point has been set.

http://www.youtube.com/watch?v=mBDykzSGk88


I hope this is not too confusing.

Regards,

Marc

Hi Marc, the first one is similar to the Draw curve / Arc / Cont (continue) tool in MoI.

Except that the MoI arc continue tool is limited right now to only working off the end of an existing curve. So with a circle like you're using there, you will need to split the circle by a line into 2 pieces, then you can use arc continue to come tangent off of the end of one of those pieces.

I think it should be possible for me to tune this up so that it works in more situations, like coming off of a circle like you show there.

The 3pts one is somewhat more difficult to tune up, that one will have to wait until after V1, but thank you for putting up those videos to help me understand!

- Michael