[question] > Circle passing through 3 points.

[.: NICKY G. :.]

This function is not present even in Illustrator AI.
Currently I can do this with the plug-in of the Astute Graphics "SubScribe".

In Affinity Designer how can I create a circle of a passing arc for 2 or 3 points?
As in the picture.

Given the arch in green, I would like to recreate the circle passing through that arch.

If it is not possible, you could of affinity consider this function, in my opinion fundamental for vector graphics and technical drawings.
Also create an arc passing through 3 points.
Like the design of the tangents to curves ...

[lepr]

.

[.: NICKY G. :.]

4 minutes ago, >|< said:

https://www.mathsisfun.com/geometry/construct-circle3pts.html

 

forgive me but do you think that I do not know how to "geometrically" construct a circle passing through 3 points?

I only ask for a simple and fast system (if it doesn't already exist) to draw a circle passing through 3 points, without having to do all that long geometric construction to find the center.

[.: NICKY G. :.]

video example

[lepr]

.

[lepr]

.

[.: NICKY G. :.]

2 minutes ago, >|< said:

What's so funny? The suggestion that it is possible for someone not to know how to draw a circle through three points? The possibility of Nickygdj not knowing the method?

"since there is no automatic way to do it in the current Affinity apps"

 

[R C-R]

12 hours ago, Nickygdj said:

I only ask for a simple and fast system (if it doesn't already exist) to draw a circle passing through 3 points, without having to do all that long geometric construction to find the center.

FWIW, in a recent post one of the staff mentioned that they would like to 'do more' with circles in the future, which might include some method for this equivalent to Illustrator's, but gave no details.

In the meantime, I think finding the center of the circle should be fairly quick & easy, but drawing it may have to be done by eye. Basically, just draw the two line segments like in the Math Is Fun example, & rotate each of them 90° using the Shift key constraint. Extend the short one in the Transform panel to cross the longer one using the center anchor & width/height lock. Then you can use snapping & the constrain proportions & create from center keyboard modifiers to draw out the circle from where they cross. Unfortunately, I don't think there are any snapping options that will snap the circle to the three points.

[lepr]

.

[R C-R]

1 minute ago, >|< said:

I think  or  or some such would be more appropriate for the lack of a snapping option for the last step. Except for that, it would take just a few seconds to precisely size the circle & delete the two construction lines.

[lepr]

.

[v_kyr]

Reminds me to ...

[.: NICKY G. :.]

8 minutes ago, v_kyr said:

Reminds me to ...

 

is this function already present in Affinity Des?
It would not be so bad in certain cases, but I would like to create an additional circle superimposed on the curve.

[v_kyr]

See the Ring shape.

[Move Along People]

-

[R C-R]

20 minutes ago, v_kyr said:

Reminds me to ...

But how would you fit a shape made with the Ring (Donut) tool to 3 already existing arbitrary points on the canvas, or to a 2 segment line equivalent?

[.: NICKY G. :.]

I'm trying to replicate the tutorial posted but it doesn't work for me.

1. I have a trace of a circle (in curves)
2. I select the ring, donut tool and with the selected curve trace I try to replicate the tutorial.

Affinity Des. wants to create me a new Ring shape and not act on the selected path ...

This thing only works if I already have a ring shape to work on!

[v_kyr]

8 minutes ago, R C-R said:

But how would you fit a shape made with the Ring (Donut) tool to 3 already existing arbitrary points on the canvas, or to a 2 segment line equivalent?

That's left as an homework exercise to you, all I said only is, that it reminds me (visually) to that donut tool.

[v_kyr]

8 minutes ago, Nickygdj said:

I'm trying to replicate the tutorial posted but it doesn't work for me.

1. I have a trace of a circle (in curves)
2. I select the ring, donut tool and with the selected curve trace I try to replicate the tutorial.

Affinity Des. wants to create me a new Ring shape and not act on the selected path ...

This thing only works if I already have a ring shape to work on!

Nah it doesn't do that or what you are looking after, what I've shown there is just partly the visual behavior of that donut shape/form tool, which reminded me somehow to what you've shown initially with the arcs.

[R C-R]

10 minutes ago, Nickygdj said:

This thing only works if I already have a ring shape to work on!

Yes, as should be obvious by now, if you just have the 3 points to start with, there is currently no way in Affinity Designer to precisely fit a circle to it. AFAIK, the closest you can get to that is what I posted earlier, which can precisely locate the center of the circle but can't set its size precisely.

[lepr]

.

[R C-R]

3 hours ago, >|< said:

The "circle" can have its centre snapped to a location and its path precisely snapped to any one of the three points, but, because it is not a true circle, the path will not precisely pass through the other two points.

Am I correct in assuming that you were using the Control key 'along a line' modifier to create the "circle" to get it to snap to any one of the three points?

I ask because beginning at some point a few weeks ago, that modifier key option stopped working on my iMac when drawing out any shape, with or without using the other modifier keys. Resetting the app has not helped so I have been looking for other possible causes, but so far no luck. 

[lepr]

.

[.: NICKY G. :.]

5 hours ago, >|< said:

Per prima cosa, le app Affinity non hanno circoli vere; si approssimano solo a un cerchio con 4 curve Bezier cubiche collegate.

Il "cerchio" può avere il centro spezzato in una posizione e il suo percorso si aggancia precisamente a uno qualsiasi dei tre punti, ma, poiché non è un vero cerchio, il percorso non passa esattamente attraverso gli altri due punti.

 

I can't, like in your tutorial, pull the circle and point to the nodes of the 3 points of passage of the circumference why?

[lepr]

.