Tangent between two arcs (circles)


Hi Everyone :slight_smile: I try draw basic pattern on blouse. It’s my first pattern in Valentina software :slight_smile:

I can’t draw tangent between arcs: Point 37 is arc from 30 and point 36 from 35. I need tangent line to connect these arcs (to create center of the front line in blouse). Please help if it 'd be done. I read latest posts on forum, but I don’t see tool which is helpful.

Generally I have problem with using some tools and not completely understand "philosophy"operating :wink:

Regards Doma


Hi, @Toffi, I’m happy that you have found Valentina.

I’ve been creating a tool tutorial that give a very basic, descriptive use of the tools that you can find here: https://wiki.valentinaproject.org/wiki/UserManual:Tools

Perhaps you’ll find what you need among them.

I don’t quite understand what you would like to do, but I’ll have a try and come back to you shortly.


Here is my try: First, I had to create a point (A24) on the one arc… I did this using the Segment an Arc Tool and used the formula: RadiusArc_B18_365/2 Next, I used the Point from Arc and Tangent Tool to create the point (A25) on the second arc. I then used the Line Tool to draw in the line between the 2 points as below:

I hope this helps you :slight_smile:


@Grace, Thanks for this. This was a lot of effort, and it’s very useful in many situations. Sometimes the points to draw the tangent line between arcs might not be easily calculated. Maybe we need a specific tool to draw a tangent line between two arcs. @Toffi, is that what you need?


@slpencer, yes, I think that is a very good idea… a tool that you may choose one arc and then another arc & a point will be created on both arcs either side of the tangent line created… because the next thing will be someone will want to divide that line by 5 or something to get a point to do something with.


Thanks Grace for speed answer :slight_smile: I poorly spoke in English :stuck_out_tongue:

Very sorry, I attached wrong printscreen :frowning: I think about tangent line which I don’t know where are located points so I can’t creation these… It must be line without the beginning and the end. Just straight secondary line. Of course I know that it will be maybe unenforceable :frowning: I sew forum and UserManual and I can’t imagine which tool would be helpful… I need draw center of the front line in blouse, then I close dart with this secondary line. I don’t know how to around this operation. I have different method to construction blouse but it’s my favourite and the best for me, especially if I’m going to move dart bust :slight_smile: On my mind is tool - example: we had drawn two arcs and we indicate arcs (circles) and then tool creates two point tangent to this circle. Later we can do this [quote=“Grace, post:3, topic:1202”] I then used the Line Tool to draw in the line between the 2 points as below: [/quote]

and we have example center of the front line :)))


@slpencer :slight_smile: it will be great. Unfortunately this is really difficult to calculated. If i’m doing drawing on paper I’m using ruler and be done :wink:


@Toffi, I’ll add this tool to the issues list. Don’t know when it will be available though.

I like this tool, it will be helpful to create some seriously beautiful pieces. Years ago, I wanted to create a quilt with letters/glyphs from David LGoines’ “A Constructed Roman Alphabet”, but I needed a tangent line function. This was with the prototype software in 2012 (taumeta.org)


Hi @Toffi

Is this more what you’d like? I used the Point from Arc at Tangent Tool from my point A24 which gave me A25 and then again from A25 back to the bottom arc to get a more precise location (A26). And then I used the Rotate Tool to move the top arc 10 degrees to the left, using A26 as the axis of the rotation, and changed the colour of the line. You can see that the rotation added ‘a2’ to the ‘A25’.


Hi @slpencer

Is there any way that we can add the colour and type of line picker to curves, circles, arcs and ellipses?

I don’t know if anyone also misses that feature but I sure do, I’ve been spoiled with choice in the lines :blush:


@Grace, I added this to the issues list at https://bitbucket.org/valentinateam/valentina/issues/681/enhance-feature-colors-for-curves-arcs-etc

In future, if you post about a new subject could you start a new thread? this helps people to find answers because the info isn’t buried in an unrelated topic. :smiley:


Thank you, will do. I’m just never clear when it’s a new topic or a continuation of a conversation :sweat:


Resolved. I made a patch.


Hello again :slight_smile:

Grace thanks very, very much. This tool is really fantastic, I didn’t know how it’s must be use hehe :wink:

I try to do this again and it’s ok. I’m so happy, because I thinking a lot of this and finally I understand what I should do :wink: My English is a weak point so I don’t understand everything from WIKI.

Instruction what I did: (it’s a different drawing but it’s the same exertions) I use tool “Point from Arc and Tangent” from point 43 and it’s give me point 44. Line 43- 44 is connected with “line beetwen points”