Updates to the Drawing Module

I'd promise to get some wrote by the end of the week, so here's my attempt on covering updates I have made to the Drawing Module over pretty much the last half of the year.

In general there's been a lot of incremental small fixes that have accumulated over such a long time, which is a stark contrast when I look at the last blog post on this and might seem significant.

One of the big changes was adding initial support for drawing the page background given the width and height and recently spending time switching the origin of the coordinate system to the bottom left with the y-axis pointing upwards - see this post. QGraphicsView orients with the y-axis pointing downwards which is also used in SVG. It's a trivial fix, where the y coordinate is inverted for the position of every Drawing Views. This is needed to ensure consistency with CAD packages and other formats.

The next step for improving the functionality is adding support for templates and displaying this on the background.

These leads onto talking about further work on improving the dimensions. The most obvious detail is the improved presentation of dimensions. There are now arrow heads, which later will be allowed to be changed to a few standard ISO options and the use of a font called osifont, which I was recommended for a starting point for datum labels. The license needs checking as it appears to be GPL 3 - I'm not entirely sure if this is compatible for distribution directly with the FreeCAD release but in the worst case an be installed separately by the user or made a dependency on the packaging front and be used if available by default.

The datum values can be used calculated as project or as true values - if an orthographic projection is used then projected values are used by default. The leader lines are also calculated to the end points of the lines avoiding any overlapping. The dimensions also use caching and now don't need to recalculate when these are moved on the canvas by the user. 

There is now an orthographic container, which contains ortho-views -orthographic projections such as front, left, top etc. These benefit of having a container is that the child orthoviews are much smarter and allow various properties such as scale or the type of projection (first or third angle) to be set from the container which are then cascaded down to the child views. 

QGraphicsView is quite flexible and allows some nice interactivity too. A little feature I implemented was having alignment between views: and can be interactively moved along one axis. You can seen in the screenshot from above the are all aligned correctly. This originally took a while to figure out because the projection used in the current release of FreeCAD is not consistent - the simple trick was ensuring that the centroid of the part is used as the origin of the projection plane. 

Another little feature I added was support for angles - although there are a few cases where an exception is thrown. The final thing I currently can think of working on is improving the print support which is slowly getting there:

Anyway that's an overview and hopefully give some incentive to give the drawing branch another try!

I'm back!

I took some time of for the later part of 2013 for an adventure that in the end didn't work out. Boo hoo!

Now I'm returning back again for 2014 for the foreseeable future! I'm pleasantly surprised to see that people are still actively looking at the pages - despite the inactivity since May and it's remarkable how time has flown. Anyway, let me introduce the new year with some good news.

From last December, I am now a Postgraduate Research student at the EPSRC for Innovation in Additive Manufacturing at the University of Nottingham. (This means I'll be working for a PhD over the next three years). It is a great opportunity to be doing particularly ground breaking research here on various areas concerned essentially with commercial 3D printing and eventually become an expert in this revolutionary field. 

As with all academic research this is non-proprietary, so in theory the modelling techniques that we are aiming to develop may reach into programs such as FreeCAD. I'll later give a brief overview of what we do here now I'm familiar with what projects have been taking place.

I'll later incorporate other posts into this blog related to my research but not exclusive to FreeCAD that might be of interest to some readers. Later on I hope to apply some experiments too. 

So where do I position my self now with FreeCAD? Admittedly these days, I don't have as much time as an undergraduate during the day, but I now have blocks in the evening where I can sufficiently give time to work on it as I choose. 

Drawing Module:

My focus is to tidy up the work that I've done over the past year on the new Drawing Module and get it into a 'playground' state where interested users can test and use it with the strings attached that non-critical bugs exist.

Later on in the week I'll try and write up an update of where I currently am with the Drawing Module - obviously with pictures!

The current big show stoppers in terms of stability and usability are the following:

• Random Draw Crashes (rare)
• Random segfaults (rare)
• Some projections are missing (tangent curves in particular)
• Dimension of edges lose their position randomly (Bug with OpenCascade)
• Background template layer non-existant

Note to people: There has been many substantial changes since May. Feel free to check out the git repo - Drawing branch and try it out! 

If you can find some solid test cases for the above in particular that would be very helpful :)