solvespace VS kons-9

We use rebase on solvespace, along with sensible squashing so most commits along master are pretty self contained. You can see the clean history here:

https://github.com/solvespace/solvespace/commits/master/

I changed a behavior to the "more standard" one because it felt obviously right. This was a 3 line change. But the was enough backlash right there in the pull request. So I spent a couple hours remembering how to add a configuration option to keep the old way for those guys:

https://github.com/solvespace/solvespace/pull/1425

> If you like Linkage, you might also like Solvespace.

No, I mean Brent Curry's Linkage[1] bicycle design software, not David Rector's Linkage Mechanism Designer and Simulator[2].

You should read Wikipedia article.[0]

N.B. About SolveSpace, as I'm its experienced user[youtube,patreon], I may say next: yes, it could be used for bike mockup, as any other CAD, but it still has a lot of limitations and even does not export correct STEP files yet[3], and in FreeCAD such STEP could fixed only partially.[video]

So, for serious 3D CAD work I highly recommend use FreeCAD (and LibreCAD for 2D CAD work) instead of SolveSpace, and use SolveSpace only as a helper tool like a calc or as a notepad for noting ideas.

About Linkage Mechanism Designer and Simulator, it is only useful for planar (2D) kinematics analyze, and if You are looking an alternative for it take a look on Pyslvs[4], that is in part based on SolveSpace's solver.

[0] https://en.wikipedia.org/wiki/rattleCAD#History

[1] https://bikechecker.com/

[2] https://blog.rectorsquid.com/linkage-mechanism-designer-and-...

[3] https://github.com/solvespace/solvespace/issues/206

[4] https://github.com/KmolYuan/Pyslvs-UI

[video] https://www.youtube.com/watch?v=F3LJMeqUDrU

[youtube] https://www.youtube.com/@appsoft

[patreon] https://patreon.com/app4soft

C++ this file covers all the math for working with NURBS curves and surfaces:

https://github.com/solvespace/solvespace/blob/master/src/srf...

There is a lot more in other files - triangulation, booleans, creation - but the core math functions are there in very readable form.

>> Maybe somebody has statistical survey of how much of the existing deployed CPU core count is typically used?

My guess is very few cores are used on average. I did some testing with Solvespace to see which build options contributed most to performance:

https://github.com/solvespace/solvespace/issues/972

Obviously using OpenMP for multi-core was the big win. But what's not shown is that in typical usage (not the test I ran) if you're dragging some geometry around it will use all cores (in my case 4 cores / 8 threads) at about 50 percent utilization. That percentage probably drops as more cores are thrown at it due to Amdahl's Law. In other words, throwing double the cores at it will give a good boost to a lot of code that is already taking less than half the time (wall clock time, not CPU time).

We added OpenMP to a number of functions for significant performance gains. And in fact, any remining single-thread operation that gets the parallel treatment is likely to have a significant impact on overall performance since that is where most of the time is spent now. At this point we're more focused on features and bugs.

Algorithmic improvements are possible and I'd like to do those in the future, but they are much harder to do than sprinkling some #pragmas around critical loops. That will improve the scalability though, where multithreading really did not.

Yeah why should we even care about s390 for some things?

https://github.com/solvespace/solvespace/issues/1264

I don't think big commercial customers are designing airplanes with it.

Very cool. I must check this out.

I implemented some L-system features in my 3D Common Lisp system: https://github.com/kaveh808/kons-9

In some small way I am revisiting the idea with https://github.com/kaveh808/kons-9

We'll see what comes of it.

I began my 3D graphics development on a Symbolics workstation at the MIT Media Lab in the mid-80's. This was before the S-Graphics suite was released. [0]

The outstanding feature of the S-Graphics suite was the polygonal modeler which used a winged-edge structure that was far ahead of its time. It survives conceptually in the Wings3D system, which is a quite faithful copy of that modeler.

And of course you got the extensibility that came with the graphics system being built on Lisp.

But Symbolics was never, as far as I saw, a serious or popular contender in 3D production. Not only was the system expensive, but the hardware could not keep up with SGI's graphics abilities. Furthermore, the mass of CG developers at the time came from a C/Unix background, and rendering especially was so speed critical that C (and Fortran) resulted in faster systems.

Almost 40 years later, I have returned to the idea of developing a 3D system in Common Lisp [1]. We shall see where it leads.

[0] https://medium.com/@kaveh808/late-night-lisp-machine-hacking...

[1] https://github.com/kaveh808/kons-9

If you are interested in 3D graphics, I have tried to keep my code simple and comprehensible: https://github.com/kaveh808/kons-9

As a solo developer of my 3D system, my main focus has been to keep the enthusiasm and momentum going and to enjoy the development process, rather than worrying about how the code might not be optimal in various regards.