# Intersection Arc/Curve & Line

Intersect curve/arc & axis tools are nice, & usable, but sometimes it would be nice to be able to just select the points at either end of a line segment instead of having to tell the axis to use the `AngleLine` going between the points of the line segment. Y’know, `click the arc/curve`, then `click first point`, `click second point`.

If I had to choose between one or the other, I’d go with what we currently have, but if we could have both functions without overcrowding, that would be nice.

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I see a use for both. In terms of creating a new tool - which entails a lot of parts - this should be relatively simple to implement as one wouldn’t have to start from scratch. More or less a lot of cut & pasting of a few existing tools. If you want go ahead and create an issue on Github.

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I am not sure if this is the same thing I was thinking about.

I was replicating a period draft which required a lot of “sweeping” from one point to find or create another point. I created an arc, created a point on that arc, but I wanted to then measure in both directions a specific amount on the arc line, from that point.

I ended up creating other arcs which crossed the original, but I was wishing there was a simpler or more direct way to accomplish this.(maybe there is and I just am too new to the program to know how to do it!)

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Here I created a line from A to A1 with a length of 5cm.

Then I created an arc (using the arc tool) with a diameter of 5cm starting at the A1 node and going to 90°.

Then I placed a point A2 (using the Segment an Arc tool) 4cm away from A1 on along the arc.

Is this what you are trying to do?

Yes, but the point that i wished to measure from was not situated as a beginning point to the arc. The point i wished to measure from was where that arc and another line intersected. From that point on the arc, i wanted to measure along the arc in both directions. Does that make sense?

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Here’s the solution I came up with, it’s kinda messy, but I think it works:

• To put forward point
1. draw a line from the center of the arc to the point on the arc
2. make an arc of the specified length, (bottom right icon in Grace’s picture,) having the same radius as the arc you want to put points on. ETA: with its starting angle being that of the line drawn in the previous step
3. segment the arc of the specified length by its own length
• For the back point
1. Mirror Objects by Line (ML), in the Operations toolbox
2. select the forward point, press enter
3. select the line going from the center of the arc to the center point
• Profit!

I hope that makes sense!

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i recreated vaguely what I was doing. I created an arc, then I wanted to measure a specific amount from point A6 along the arc (downwards) , to create a point, as well as measure up wards along the arc another amount. ! can see now that I can get the info on the arc length and try to place points that way, I guess I was thinking there must be a way when doing that to input the point to measure from.

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I will see if I can make sense of it, the more options the better! thanks

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@Ttailor I just realised that I forgot to put one of the essential steps! I have edited it in to my previous post.

The arc start point will be `AngleLine_A_A6` in your case here.

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Hallo Schneider was genau wolltest du konstruieren? Schulterpunkt? Ich habe festgestellt, dass man, wenn man zuvor immer nur auf Papier konstruiert hat, in der Herangehensweise sehr umdenken muss. Beim Konstruieren auf Seamly muss man vielmehr vorausdenken, weil spontane Änderungen nicht möglich sind und meistens müssen Zwischenpunkte gesetzt werden, dass es zu einer passenden Lösung kommt. Ich arbeite gerade einen einem für mich perfektem Gerüst, damit ich später leichter und schneller zu Ergebnissen und Veränderungen komme.

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I am still learning the software. I was trying to reproduce a vintage early 1900’s draft as an exercise in learning more about seamly2D. i am realizing exactly what you say- on paper it is more spontaneous, with Seamly, I need to rethink and the old ways require a different approach

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Fragen Sie, wenn sie etwas nicht erarbeiten können. Bin jetzt schon etwas länger dabei und habe so manches Problem in den Griff bekommen:)

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This is my humble attempt at period pattern making from the book “Parisian Ladies Tailoring”. As you can see, everything is very mathematically created using curves and tangents. And yes, it does teach you all there is to know about the tools in Seamly and how to get from one point to another. It also teaches about which measurements to use where to achieve what.

However, since I have no need for period clothing, I switched to learning from the Aldrich books that are much easier to convert into digital flat-pattern making. Since then, I have worked my way through a number to books & internet tutorials, in my quest to really understand pattern making in general, since I only started learning it after I found Seamly.

@Scholli, @Douglas, @slspencer, @Pneumarian and a whole bunch of others are light years ahead in pattern making than I am. However, I have made a number of patterns for clothing for family & friends that do fit very well and make up very nicely, as well as some bag patterns and even some cardboard cupcake box designs for the local baker.

If I have to give you some advice, it would be to read the step-by-step instructions a few lines in advance so that you can plan in your head which line of instruction to create next. Sometimes, it’s better to skip a line and do it afterwards, since Seamly needs to have one node to flow off a previously made node or arc, unlike when drafting by hand, where you can go off & tack in a bit anywhere on the paper.

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This was what I was working on. A waistcoat from TheClimax System c.1920 I am merely using these as a means to learning the software. I can usually figure out a way through trial and error, but I am also like to know if I am missing the obvious or the easier way to accomplish a task! I have way more pattern making experience than software experience! I do want to thank everyone who responds- it makes for a great sharing experience!

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Wow! they do look very similar.

It seems to me that you’re actually doing very well. There are a few topics on here that may be of interest to you, like the ones on creating curves that will stay smooth when the sizes change, since we can’t use curve rulers. Like these:

With all the tools, there is a small help feature in the bottom right corner of the drawing board, which pops up as soon as you pick up a tool:

And when a formula returns an error, a small description of the error will appear if you hover your cursor over the word ‘error’:

These are 2 things that I didn’t realize when I started out, but once I found them, they have proved to be of immense help.

As far as an easier why to add points on either side of your arc is concerned, if it were a curve, then yes, I could suggest one, but with the arc, it’s a bit more complicated. You could choose intersect line & arc or intersect 2 arcs, as an arc is, pretty much, a free-standing object only connected to anything by the node from which the radius is measured. So until you do place a node on the arc, there is nothing to measure from along its circumference.

In your image, if node A13 is a certain distance from M, the you could use the tool Point at Distance Along Line, instead of creating the arc first and then intersecting it.

So, yes, there may be other tools that could make the workflow neater & easier, but only by using the tools and knowing what they do, will you be able to grab the correct tool for the neatest & easiest desired result.

Other than that, please don’t hesitate to ask. We’re all happy to help.

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