I want to sketch some simple diagrams to accompany the inverse kinematics calculations for a robot dog design. I'll want to draw and colour simple shapes, draw axes, arcs to identify angles etc.

I have spent hours trying to do this in LibreOffice Draw, Google Drawings and Inkscape. I cannot believe how unintuitive these programs are. I cannot get LibreOffice to draw decent arcs for angles, and the tools are atrocious to use. Google Drawings is better, but still pretty awful. I thought Inkscape might be the answer until I needed to draw some lines to denote axis orientations - I can't find out how to draw a simple line !

I could have done this in 30 minutes back in the 80s using MacDraw ! I can't believe how difficult it is in 2021. Can anybody recommend a simple program which allows general purpose diagrams ?

krita ftw!

Unfortunately, the tutorial does not mention lines.

Click on "Draw Bezier curves and straight lines". Then, click to draw an endpoint. Double-click to end. Go to "Object -> Fill and Stroke" to set the stroke style.
Ed

Dia is the simplest program that I know for drawing simple diagrams. “Simple to use”, that is. There are so many templates that some types of diagram are drawn by placing objects on the grid.

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Thanks for the tip. In the end I managed to do the job with Dia.

I still found it to be an uphill struggle compared to software that I used in the '90s ! Dia will not allow you to 'flip' or 'mirror' a group (on the internet it suggests editing the XML to achieve this !). When I tried to rotate a group it rotated each element separately. It can't maintain the aspect ratio of a group. It can't force lines to be horizontal or vertical by holding down shift. I had to use 'refresh' continuously because Dia had no idea how to redraw automatically. etc, etc....

I am quite depressed that I cannot do such simple work in Linux. I would hate to have to return to Windows, but the state of the tools is abominable (unless I am missing something). It seems like there is a ton of half-finished, half-baked software, but nothing that is really usable.

Ever think about freeCad? Just a thought. I see there are plenty of tutorials (youtube) on kinematics within that applications. I've used freeCad to design some simple parts for 3d printing, and laser cutting .... but no experience with animation of the parts! Just throwing it out there as another resource.

The frustration is probably bigger with the people who begin and try to produce something useful. I do not know much (about anything) but in the same way that all that XML stuff (svg inclusive) liberates us of so many restrictions, it asks us to do quite stupid work and sometimes downright idiotic configurations before we can even think of using much of the “modern & state of the art“ software.

Personally, I would *love* to run the old (outdated or what) “Topdraw” (*not* the medical stuff) in a Wine-session. If you stumble about it somewhere .., you will not be able to, but comprehend.

Edit:
What you can do with any object or group of such objects may depend on the template that you use. Objects that I create from primitives can be manipulated in any way, also after being united (i.e. being transformed into a union). Colored objects from some templates lose their color.

Edit II
Rotation support in Dia 0.98: