Tag Archives: Task

Logarithms: Better than bad, they’re good!

Yesterday’s work was focused on two different TO-DO items:

1) I did a little bit of work on the position dialog box, as requested on the forum a few days back. The position dialog has two modes, incremental and not-incremental (I’ve been calling that one absolute), where the position indicated to the dialog is either applied against an object’s current position (incremental), or against the origin of the coordinate space (absolute). That mode is selected by a checkbox, the requested feature was to make the state of that checkbox persist between uses.

Screen Shot 2015-04-24 at 2.13.25 pm

In addition to making the checkbox state persistent, I ended up also changing around the transitions between the two modes a little bit, so now that part works a little more intuitively. Now, when incremental mode is entered, the GUI widgets are initialised to reflect the equivalent incremental placement to the change in absolute position that had been in the GUI before.

I suppose a video clip would’ve been a clearer way to convey the original problem and my changes…

2) The auto-scale in Drawing had a few problems, so I’ve re-worked two areas to resolve those.

First, there’s a little function (Attributed to David Eppstein, whose blog led me off to reading about the Harriss spiral – neat stuff) that takes a scale value and computes a ratio of two integers that closely approximates that scale. The problem was that the function wasn’t really setup for handing big or small scales, so I wrapped it up with a little math to essentially deal with adding 0s onto either the numerator or denominator depending on the scale.

Second, the algorithm for calculating the initial scale to use didn’t handle small scales very well. The re-work there was a little more involved, but fortunately a lot of my earlier work on the placement of orthographic views was useful.

So, now it’s easy to use the drawing workbench for bigger or smaller things than it used to be, though there are still a couple issues. One of them is that there’s a hard-coded level of detail parameter somewhere, which I intend to do something about. So, right now if I try to draw a sphere the size of Earth, then it gets computed to some absurdly high resolution, 0.01mm or something along those lines. There’s a similar problem in the regular 3D view part of FreeCAD too, for instance at the default settings a circle drawn in Sketcher looks like a 30-something sided polygon, so maybe that issue requires a bit more thought.

Incremental changes

Yesterday was spent mostly as anticipated – picking up my shiny new/used monitor (quite happy with that purchase) trying out the new Enumeration class (minor success, needs a couple small changes before further testing), tying up some loose ends in Drawing, etc.

From a user’s perspective, the main change to Drawing is that isometric views are now constrained so they’ll only move in 45 degree angles from the Front view, much like the normal orthographic views move only vertically or horizontally from the Front view. I’m not 100% happy with the implementation here, so may do a bit more work on that later – the movement can get a bit jittery when isometric views are moved too near the centre of the Front view, although there’s not much good reason to do that anyway.

But! I also tracked down the source of a bug that’s closely related to the one discussed previously in Bounding Bounding Boxes. Isometric views were sometimes being positioned a little strangely, which became more of an issue after their positions were constrained. The problem is that the centroid of an object’s bounding box is dependant on the orientation of the bounding box. The isometric views end up wanting a bounding box for the object that’s not aligned with the originally calculated one, so they sometimes are not centred on the origin. A fix for that is first up on my list for today, though I’m a bit slow with this Open CASCADE 3D geometry stuff.

Refactoring

Today was spent on a few different aspects of the project, with a brief interlude to deal with some external (car) stuff. First thing, I got caught up on emails/forums, then did a bit of shopping*, then on to programming! For better or worse, the changes I made aren’t involved in any new features, and didn’t address any specific bugs that I’m aware of (though, I did find a couple possible sources of bugs). But, I think it was a valid use of time because I learned a bit more about the internals of FreeCAD, and think I’ve also cleaned up those internals to a degree.

In object oriented programming, there’s a distinction between “is a” and “has a” relationships. My project today involved splitting one class into two, to make this particular area a bit more consistent and to allow for the use of one piece of functionality provided by the original class without the other.

Specifically, FreeCAD has several classes descended from a parent class Property, which are used to store various pieces of information to be saved into configuration or project files. These are the things that are modified by the Property Viewer. The refactoring I did today took a descendent of the PropertyInteger class – PropertyEnumeration – and made it instead derive directly from Property and contain a (new) Enumeration object. So, PropertyEnumeration now “is a” Property that “has an” Enumeration.

There are a number of reasons I worked on this, none of them is terribly compelling if taken alone, but to me it fell into a category of “things that I’d want a professional programmer to fix, but that I wouldn’t bother with as a hobbyist”. So, the project for tomorrow is to try out those changes in the Drawing-dev branch (which is where I came across a use case for them), then clean up and submit them for testing if they seem worth the trouble.

Also intend to tie up a couple loose ends in Drawing. I’d like to try a couple different options for constraining the position of the new isometric views, then there’s a bug that causes newly added views to not be scaled appropriately sometimes.

Oh! This evening I went over to the maker space and learned a couple interesting things. First, there’s a possibility that I can get access to some machine tools in town! Second, that it’s possible to print nylon with filament type 3D printers, and that some neat things can be done by designing air bubbles into 3D printed nylon parts. That’s got me thinking about a project that was discussed at South Pole – making a 3D ice printer. I’m sure someone has done it already, but it does seem like a fun party trick regardless.

* As for that shopping; I’ve arranged to buy a monitor (2nd hand local), and bought a 3D mouse (amazon). I’m quite intrigued by these 3D mice, looking forward to having one to play with aside from the obvious need to have one for work purposes.

Update

Today was supposed to be a “weekend” day, but a number of events transpired to keep me in front of the computer for much of the day.

First off, I spent some time cleaning up the changes I’ve been working on in the Drawing workbench, and getting them pushed up to github. The main two items are a re-work of code involved in generating “wires”, which are what OpenCASCADE calls collections of edges, some work on BSplines, and the isometric projections. There had been a couple bugs in the BSpline and wire code, finding and fixing those occupied most of yesterday. Now, the Isometric projections aren’t completely done, but they’re usable and I just need to make a few design decisions to finish them up.

A couple other smallish bug fixes made it in, and a lot of cleaning up/commenting source code. There’s a discussion ongoing on the FreeCAD forum regarding code formatting/reviews/etc, so have been occasionally getting distracted by thinking about that stuff too.

Will probably take tomorrow “off”, as I need to take care of some things out of the house, but stay tuned!

Tax Day summary

Mainly this morning was devoted to things outside of FreeCAD, but I made a bit of progress on a couple bugs too.

It took a while to get started, as some other changes to FreeCAD broke the new Drawing module. I’ve been trying to keep the new Drawing module up-to-date with the rest of FreeCAD, to avoid a giant merge headache at the end, so this morning was one of the temporary smaller headaches that are a consequence of that decision.

Bug hunting/fixing involved implementing a small change I figured out yesterday (to fix the dragging bug), and re-working of some code for handling B-Splines (to prevent some exceptions that I think are related to problems in other areas). More to come, but not today!

little things, and The Process

While I was playing around with FreeCAD today, I felt a little twinge of frustration and decided to do something about it. Perhaps my loyal reader will find the process of identifying issues, fixing them, and publishing fixes interesting?property viewer

There’s a widget, the “Property Viewer”, which is one of a few key GUI components in FreeCAD. It contains two lists of properties (dimensions, positions, colour, etc.) for the thing you’re working on, and allows them to be changed. There are other ways to change most properties too, but the Property Viewer has everything in one place and is usually accessible.

The Property Viewer has two tabs; Data and View, so you can either work on Data properties or View properties at any particular time*. The issue is that I manipulate Data properties much more frequently than View properties, but FreeCAD always starts up with the View tab in front. So, I usually have an extra click to get Property Viewer in the right mode for changing the properties I’m interested in.

To fix this, I added ~20 lines of code to save the last tab that was selected, and to select that tab next time FreeCAD opens. Then, I “pushed” that modification to github, and made a brief post to the FreeCAD forum to ask people to try it out and comment. Assuming that my change doesn’t cause any problems and people like it, in a few days I’ll submit a “pull request” and one of the core developers will bring the code in to the main FreeCAD codebase (unless they notice a problem in the new code). Not all changes justify asking for popular opinion and testing, but that’s a judgement call. This particular change affects a core GUI component of FreeCAD so I felt like it was worth asking.

Every now-and-then, a “release” is made of FreeCAD (incidentally, we just made a release today!), next time that happens, any changes incorporated to that point will be included. Releases happen every few-to-several months, so in the meantime people can only get the new changes by building from the latest source code, which is what some of the early posts on here, for instance the one about building on OS X, are about.

All that said, the process for the Drawing module, which is where I’ve been doing most of my work lately, is a bit different. At this point there are only a couple people working on that module, and we’re working on a fairly significant re-write that involves breaking the existing Drawing module. So, rather than asking for comments and incorporating changes into the main FreeCAD, we [even more] informally push and pull our work to/from github to keep the latest and greatest moving forward. Eventually, when there’s some consensus that the module is ready to go, we’ll go through a testing phase with the wider FreeCAD community, and hopefully the whole thing will eventually be a part of the main codebase.

* Of course, as I type this, I realise that it might make sense to just get rid of the tabs altogether and just put all properties in one widget…