## Re: [Inkscape-user] joint-and-wire-type polylines/fixed length line segments?

 Re: [Inkscape-user] joint-and-wire-type polylines/fixed length line segments? From: Maarten van der Velde - 2013-09-24 14:45:22 ```Maybe we could look at it from another 'angle'? This way of reasoning can also be founnd in programs like SolidWorks (parametric modelling), where it's all about 'degrees of freedom' . Looking at two points in a 2-dimensional plain with a line between them, there are 4 degrees of freedom(*). Presently, Inkscape doesn't fix any of these. But you could image that when two nodes are selected, Inkscape would allow us to partially 'fix' the relation between them. We should be able to tell Inkscape, for example: -Node A is always 3 centimetres to the right of node B and 4 centimetres to to the top or -Node A is always 3 centimetres to the right of node B, but the vertical position is free or -the distance between A and B should always be 5 centimer, but their angle is free (this situation reflects the idea of the original question) or -the angle between A and B is always 36 degrees, but the distance is free. These relations could be made pair-wise, so also between A and C and B and D. But, the number of relations should not be larger then the total degrees of freedom. (*) You can look at this in a number of ways: (1) two points have both two ordinates (x,y) that can all be set independently, which makes 2 cordinates x 2 points = 4 D.O.F. . (2) One point has one set of ordinates, the other has a relative distance to the previous. On Sep 24, 2013, at 12:49 PM, alvinpenner wrote: > This is a very interesting idea, but I don't know what it is called and am > fairly certain that Inkscape does not currently support it. > The problem is that there will be some ambiguity as to how to impose these > constraints. For example if you have a line segment with 5 points ABCDE, and > you start pulling on A to make the line longer. Initially you will be able > to deal with this just by adjusting B alone. But at some point ABC will be a > straight line, so you will now have to adjust C as well. So now there is > ambiguity, should you adjust C on the assumption that ABC remains straight, > Or should you adjust both B and C simultaneously to deal with the change in > A? And what happens when the entire line ABCDE is completely straight? > Should all stretching movement now be forbidden or should the entire line > move as a straight line? And when you start to compress the straight line > length by moving A inwards, should you adjust only B, or should you perhaps > move all the points equally to introduce curvature to the whole line? > Anyways, I would be very interested to see if anyone has ever tackled this > problem. > > Alvin Penner > > > > > -- > View this message in context: http://inkscape.13.x6.nabble.com/joint-and-wire-type-polylines-fixed-length-line-segments-tp4968180p4968181.html > Sent from the Inkscape - User mailing list archive at Nabble.com. > > ------------------------------------------------------------------------------ > October Webinars: Code for Performance > Free Intel webinars can help you accelerate application performance. > Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from > the latest Intel processors and coprocessors. See abstracts and register > > http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk > _______________________________________________ > Inkscape-user mailing list > Inkscape-user@... > https://lists.sourceforge.net/lists/listinfo/inkscape-user ```