Hello Michael Gibson!

I show here a workflow to use moi exported curves in Hash Animation Master.
It has AI importer and automatically can create patches from curves. But problem is,
that the intersections need to meet to merge at points. Animation Master has curves through points.
Moi has also nice tool Draw Curve -> Through Points, But i need a visualization option next to "Show pts".
Option like: Show Points On Curve.

Also to note to this theme, is that when you use polylines, they come into Animation Master as peaked curves. You can
then adjust IN and OUT magnitude for them to smooth out created patches. But if i could use curve trough points to build
networks, it makes a perfect solution in terms of curve shape construction and model planning.

Also in terms of control, because you can join segments of lines to control how polyline flows.

Hi Allan, could you describe in some more detail what you would want the "Show Points On Curve" to do?

One thing to note is that MoI uses a system of curves that is called "NURBS curves", and when you do an Edit > Show pts, that is showing the control point hull for the NURBS curves.

When you export to an AI file, the NURBS are actually transformed to a related kind of a curve called a Bezier curve, which can be done by splitting up NURBS curves into smaller pieces.

So the points that you see in the AI file have actually gone through a kind of transformation, the NURBS curves that you are working with in MoI can be diced up like that into small pieces but normally they are made up of a longer series of points, which is one of the things that makes it easier to make a totally smooth curve with NURBS which is harder to do (beyond tangency) with a simple chain of Beziers.

It kind of sounds like you may be asking for showing Bezier style points in MoI, when MoI is actually using NURBS curves and not strictly Beziers.

- Michael

Hi Allan, also another detail is that certain kinds of curves that you create in MoI such as circles, arcs, and ellipses are what are called "Rational" curves. These are curves that have a "weight" value associated with each control point in addition to the x,y,z values.

The AI format does not have any mechanism in it to represent weight values for rational curves, so for these kinds of curves when you export to AI a new non-rational curve is created to approximate them by an adaptive fitting process.

So once again what I'm trying to describe is that in many cases the output to AI is not 100% the same as what is used at run-time inside of MoI. There are a couple of different kinds of transformations of the data that are going on, so the "AI points" that it seems like you are interested in do not actually exist in MoI during its normal operation, they are calculated at export time in many cases.

The points that you currently see with "Show pts" are the points that MoI uses for defining the curve.

One way you could get the exact same points displayed is if you only create 4-point control point curves (with the Draw curve > Freeform > Control points command) which will be the same thing as an AI bezier curve, and then make longer curves by chaining several of these 4 point curves together - that's how a Bezier curve system works internally. But that will be quite awkward, since MoI is overall more designed to work with NURBS curves.

NURBS curves were actually invented in order to make a more smooth curve than what you can normally get by just chaining separate individual Bezier segments together.

- Michael

I think is it not possible to memorize points that were put in place when drawing with Curve trough points?

I have used Rhinoceros 3d evaluation program, and there exists such possibility: two ways to display curve points.

Hi Allan, in the future I might try to set up something like that using a history mechanism, where the points that were used for a "Curve through points" would be adjustable later on.

The alternate point type that Rhino uses tends to not be very useful, it tends to cause a lot of wiggles in the curve when you move around those alternate style points. That's why I have not focused any effort on trying to do those particular ones in MoI.

If you want to have the points for a "Curve through points" to be present, maybe one solution would be to draw in point objects beforehand, and snap on to those while drawing. Then you will have those point objects still around as markers.

To draw a point object in MoI, go to Draw curve > More > Point:




You can use that command to put in points which can act as persistent markers to snap on to a particular point again later on.

- Michael

Hi Allan, here's an example of why that "Edit points" mechanism in Rhino is just not good for actually editing a curve.

Here in Rhino I have drawn a curve through points, and then turned the "Edit points" to be on:



Now look what happens when I move that selected point:




Notice how the curve has become strangely lumpy and bent in the middle, and a strange hook has formed at the end?




When you move those "edit points" in Rhino around, you do not actually get the same result as if you had drawn a brand new curve through those points.

I wanted to add that in to Rhino mostly because there was a mechanism for it in Alias, I didn't really know at the time how bad of an editing tool it actually was going to be.

- Michael

Thanks for your response, Michael Gibson!

Maybe we could just have a way to visualize these points, not to edit afterwards?

Hi Allan,

> Maybe we could just have a way to visualize these points,
> not to edit afterwards?

Well, frankly that would be kind of weird, because for the majority of users it would not really serve any purpose. It would lead to a lot of questions about "why are you just showing these points and not using them to edit?" ...

If you want to refer back to the "through point" later on, currently the way that you will need to do it in MoI is to place that point in before drawing the curve as a Point object, and snap on to it while drawing the curve.


I do think that in the future at some point with a more complete history editing mechanism it will be possible to do something more directly like what you are asking about, but I'm not sure when that will happen.

- Michael