Hi Pilou, also note that the method that I recommended earlier just does not work right, for actually a couple of reasons (sorry I led you astray!).

One reason is that you'll need to get equal length line segments which is not necessarily easy to automatically generate.

Then the other is you need to arrange things such that the point used for each array instance along the polyline falls within the midpoints of the polyline rather than right at the juncture between 2 segments. That's because if it is at the juncture between segments there are 2 possible tangents for that point and any small deviation from one side to the other will use one of those 2 possible tangents.

That's another reason why this would probably work best as a special tool that copied things to line segments rather than using the general purpose array curve for it.

- Michael

Hi Pilou,

> Yes I understand that, but it's just funny that the function
> "works" for a volume and not for "2 lines" (for my point of view) :)

For an open path curve like this, it works in an identical way for either one...

If you test with replicating a volume, just make sure it is in the same orientation as the line - for example your triangle line starts out at a slight angle so that it is aligned with the first line segment which is not exactly horizontal.

If you orient your volume in the same starting position, you should get an identical result with it as well.

If you forgot to have the same starting alignment, then certainly you will get a slight difference.

But I'm afraid that I confused things a lot more by posting that method which does not work, sorry! :)

- Michael

All that can't be easy solved by "Instancing" a volume array / curve then replace at the end these volume by the "2 lines"?

Instance of objects is not projected in early Moi version?

Hi Pilou,

> All that can't be easy solved by "Instancing" a volume array /
> curve then replace at the end these volume by the "2 lines"?

No, not if you want things to touch each other exactly.

Making an arrangement where items sort of "tile" to fit in available space is a rather different problem than just regular "instancing".

To make things fit and touch each other, you can't just replace one object with any other object, things need to be of specific sizes.


> Instance of objects is not projected in early Moi version?

I'm not really sure when. Definitely it won't be in v2 though.

- Michael

Can't wait for instances...........!

Anyway I guess it would work manually by placing circles with a predetemined radius at each intersection like this:





Then just draw each line to each intersection. This would achieve the same result. Currently i think the MOI intersection snap could be improved: when I try and rotate the line in my previous post from one end and using the far end of the line as the rotation point when I intersect the elipse im wanting to snap to the intersect just runs up and down the elipse line rather than just snapping firm to where the official intersection hits it i.e. when the endpoint of the line hits the curve as it is rotated. Could this be improved?

Cheers

EDIT: If moi could do the circle technique (IE straight line distance between points where the circle of radius x intersects the line) internally like it does the number along the curve at the moment, then that would help to get the right base size for the initial element, at the moment that would be very much trial and error and not very 'CAD' like.

A solution can be :)
Array curve a point to the ellipse
--> length base curvy triangle
create a cone 3D with radius = 1/2 length base triangle
Array curve cone to the ellipse
Extrude ellipse
Trim cones with extruded ellipse
et voilà
triangular surfaces arc-elliptic are equal ! ;)
If you want real straight triangular : polylining the 3 vertex of the triangular surface arc-elliptic :)

Hi Rob - currently intersection will not find that point you are talking about because it is not an intersection between existing geometry in the scene - it would be an intersection between a circle and that point. But there is no such circle in the scene currently, if I understand the situation you are referring to.

But maybe I don't understand exactly what you are asking about there.

I think it could be possible for me to add in a kind of "implicit circle" though.

There is actually such a thing already implemented in v2 for distance constraint.

If you activate distance constraint while drawing a polyline for example (just type in a distance value and hit enter), then you will get intersection points for a circle of that radius.

Is that the kind of thing that you're talking about getting for Rotate as well?


> EDIT: If moi could do the circle technique (IE straight line
> distance between points where the circle of radius x intersects
> the line)

If I understand correctly, it needs a much different kind of solving technique to get equally spaced "chord distances" in the result rather than distance as traveled along the curve.

I believe it will need to be calculated with a kind of iterative solving technique, not one that just divides distances in a simple and even method like the current array curve does.

I would think it would be a specialized command, like "Create uniform polyline from curve". It's trying to solve a rather different problem than what Array curve is intended to do.

- Michael

My Methode seen above :)
Very easy :)
Mirrors are not necessary if you make the complete ellipse in one pass ;)
Surfaces triangular arc-elliptic are more natural than straight triangles surfaces !

Hi Pilou,

> My Methode seen above :)

Looks like a good method for the purposes of visualization!

But I think for the purposes of architectural design for construction, there will be some desire to have a very regular and uniform shape, where each triangle touches the other one at the same height above the ellipse.

I'm not sure that your method will produce that degree of regularity but it looks like a good one to at least get something that looks close to the desired output.

- Michael

Precision is given by a point Array curve/ Ellipse -->radius base of the cone 3D
so 2 decimal point after unity ;)

Hi Pilou,

> Precision is given by a point Array curve/ Ellipse -->radius
> base of the cone 3D so 2 decimal point after unity ;)

You didn't include a 3DM model file, so I'm not completely sure, but I think your method may result in cones that are not touching each other exactly.

For example if 2 cones are touching each other like this:



But then 2 other cones are touching each other like this:



Then the way that your intersected results touch between each piece will be not completely uniform.

That may make that result unsuitable for architectural construction.

The other thing is it looks like your result makes curved surface pieces? Often times this kind of paneling for architectural design it is desired to have planar pieces for the construction.

It is not unusual for architectural design to have some special requirements beyond just making it look good - I think it is possible that your method may not meet those requirements.

But it does look like a good way to get a visualization of something that looks similar to the desired result though!

- Michael

Seems remember my cones were perfectly fitting! (0.01 cm)
I will remake that ;)
Yes it's not planar of course : in this case must be hand drawing :)

Hi Pilou,

> Seems remember my cones were perfectly fitting! (0.01 cm)

You mean you measured each one to make sure?

It looked like you used ArrayCurve to distribute the cones - like I was discussing earlier when you use ArrayCurve it distributes things at equal distances as traveled along the curve.

The distance "as traveled along the curve" and the "straight line" distance between the centers of the cones are different things.

- Michael

here the 3Dm
I don't use polyline : just array curve
triangles are over the spline with 0.01 cm so just drop down
between each base triangle there is 0.01 cm

Hi Pilou, in your example file the cone centers are not all at the same "straight line" distance from one another.

For example here I drew 2 lines in between some of the cone tips.

This line is 1.13 units long (actually 1.1263 with more digits if you open up the size edit panel).



This line is 1.11 units long (more digits: 1.1143):



So actually more than 0.01 units deviation between them.

It basically needs a different technique, to generate a set of lines that are all equal sized, to get better uniformity in the results.

- Michael

yes it's the price to use the array curve methode :)
0.02 cm for a building it's not the painting :)
Maybe I willl find a better method

Hi Pilou - for construction the real problem is that for different kinds of path curves the amount of error with your method will be unknown until you measure each thing.

For a rendering or visualization purposes only, that should be ok but probably not as a basis for a physical construction.

Array curve just is not the right tool for this particular job - it does something different (making equal distances as traveled along a curve) than what is actually needed in this particular problem.

- Michael

Thanks Frenchy for your dedication to the cause! However I think it was really the principle I was addressing not specifically solely the triangle shape but a method that could be used that with any shape (like the tank tread example) that just used two end points in a straight line to determin the start and end of each segment. But good thinking outside the box!!

Michael- yup i think you have understood me on my snapping point. Here is a better example - I just want to snap the end point of the line to the implied intersection between the radius of the base point of the line and the curve im intersecting to. Currently point will just slide up and down the curve which is useful in many cases but would be good to also have this intersection snap too. I think a picture is definately worth a 1000 words in this case!.....









Re the straight line snap I can see the dificulty in determining the exact measurements for the implied circular intersections for an even split but i guess it would be easier for a purely fixed size measurement, that would save a fair bit of manual placing and rotating.

< not specifically solely the triangle shape
of course :)
the damned thing is that : the "Array curve" seems works fine with a "circle" :)

Hi Pilou,

> the damned thing is that : the "Array curve" seems works fine with a "circle" :)

A circle is a special case, where if things are split up into equal segments "as traveled along the curve", it also happens to have equal distances "as connected in a straight line".

For example if you split up a circle into arcs where each arc is the same length, then the "chords" that connect the endpoints of each arc will all be of the same length as well (same length as all other chords I mean, not the same lengths as the arcs).

With other curves that is not the case - in other general curves making points that are equal distances traveled along the curve result in different lengths between the connecting "chords".

- Michael