Software suitable for drawing knots

[Mangetout]

I’m looking for a program that will make it easier for me to draw knots - at the moment, I’m doing it in Powerpoint (yes, I know), and it’s a real PITA because it isn’t possible to have part of an object lay over the top of another part of the same object (at least not in the sense I need).
Here is a picture of a typical knot - I had to draw this one as follows:
-Draw the knot with a thick black line
-Copy it, thin it down, make it red and place it over the black line (makes a red line with black edges)
-Draw in the edges of crossings by hand - otherwise it looks like this - and it’s completely ambiguous as to which thread is laying over the top of which.

With a simple knot like this one, drawing in the six edges of the crossings isn’t a big deal, but I want to draw some configurations that are very much more complex (the reader won’t have to work it all out from a single picture - it will be step-by-step, but I want the program to manage the crossings for me without me having to worry about manually maintaining the Z order)

So… is there a graphics program out there that can make this all a bit simpler for me?

[si_blakely]

@Mangetout

I’m looking for a program that will make it easier for me to draw knots - at the moment, I’m doing it in Powerpoint (yes, I know), and it’s a real PITA because it isn’t possible to have part of an object lay over the top of another part of the same object (at least not in the sense I need).
Here is a picture of a typical knot - I had to draw this one as follows:
-Draw the knot with a thick black line
-Copy it, thin it down, make it red and place it over the black line (makes a red line with black edges)
-Draw in the edges of crossings by hand - otherwise it looks like this - and it’s completely ambiguous as to which thread is laying over the top of which.

With a simple knot like this one, drawing in the six edges of the crossings isn’t a big deal, but I want to draw some configurations that are very much more complex (the reader won’t have to work it all out from a single picture - it will be step-by-step, but I want the program to manage the crossings for me without me having to worry about manually maintaining the Z order)

So… is there a graphics program out there that can make this all a bit simpler for me?

MS Visio can do this (guessing you have Office installed) - just with a heavy bezier line style and a shadow.

Or assemble it out of bits (linked at the end points) and use the Z-Order to get it all correct.

I did the same with Xara Xtreme on Linux, too.

Si

[Mangetout]

Thanks for that - I’m going to install Xara Xtreme now and try it. I wonder if Inkscape will do what I want…

[stolichnaya]

Everything that I know will require you to split the “rope” into elements. But you can still simplify things - if I had to do this I’d probably draw the knot with intersections and then slice the shape at the appropriate points to create the proper overlap. I would use Illustrator and the knife tool for this.

3D is an excellent option but I am none too skilled with it and knots seem like a difficult problem to solve, and I would guess that the output wouldn’t be as attractive.

[Mangetout]

Xara Xtreme looks promising so far, but

-How do I set the colour of a shadow?
-How do I join objects? - If I group them, I can’t access the handles to adjust their curves, also, I’d have to do the alignment of the butt ends manually this way.

[Mangetout]

Also… The shadow tool wants to cast a shadow at the ends of the bezier lines, which is going to show the joins…

[cantara]

This site has a lot of really good pictures and animation. I seem to recall him detailing what he had used to draw them, but I can’t seem to find it now. Maybe he’s removed it.

[Mangetout]

Thanks for that, cantara - I’ve seen that site before but it completely slipped my mind. I contacted the author, who replied with some very useful info:

Ian Fieggen wrote:
…

I used Adobe Illustrator for the majority of the drawing, as this allows
nice smooth curves. However, the “depth” is due to shadowing, which was not
so easy to achieve in Illustrator. The diagrams were therefore imported into
Photoshop, where the shadows were added manually.

The most difficult process with doing the diagrams comes when one string
passes both over and under another string, as it does with even the most
simple overhand knot. Each element of a diagram can be above or below
another element, but not both! To go over and then under, I therefore do one
of two things:

My original method involved creating two versions of the image, one with the
yellow portions on top of the blue portions, the other with the blue on top
of the yellow. Paste both versions of the image on top of each other into
Photoshop as two separate layers. Then use the eraser to rub out any
interesctions that are incorrect (eg. blue over yellow), revealing the
correct intersection on the other layer below (eg. yellow over blue).

Another method is to use the “Pathfinder” tool in Illustrator to chop one
path where it overlaps another path and should be underneath. With the path
chopped at the point where it intersects, the result looks like it is
actually running underneath.

On some of my diagrams, this is LOTS of work because the lines are actually
comprised of a coloured line with a black outline. I end up with one layer
comprised of all the underlying black, with the yellow, blue and grey
segments all lying on top, each neatly cut to their exact shape.

Anyway, that’s how I’m currently producing my diagrams. You may instead
choose to look at a free program called “KnotPlot”, which is full 3-D knot
drawing software. I found out about this too late because it would mean that
I’d have to re-do all my existing diagrams as well, but for you, it may be
perfect.

Anyway, I hope that’s enough info to get you started!

Have a great day,

Ian Fieggen

The double-layer idea is a great one, knotplot looks really good as well.