XD16, and XD17 trial SVG import issue

[simsmj]

They are actual SVG-XML files. The reason for the interest is that shortly after I retired more than seven years ago I took up an interest in CNC milling, and bought myself a Shapeoko kit, and built it. The first plan was to design and build a mount that would let me attach my then iphone 4S to a pair of binoculars so that I could take a better photo of the moon. To mill something out of a material you need to draw it in a suitable prog (Xara was perfect!) and export the drawing as an SVG to another prog to specify and produce the toolpaths the CNC toolbit would follow while meandering through the material at various depths to cut out your drawn shapes.

The toolpathing app I use most often is an open-source utility called makercam.swf which only accepts SVG, while others can also accept dxf files. Both of these are vector-based. Makercam generates gcode which is a essentially a list of x,y,z coordinates to go to in sequence at set speeds and in either a straight line (G0 or G1 x y z) or an arc (G2 or G3 x y z, clockwise or anticlockwise, with other parameters). The CNC machine is itself vector-based.

I had been using makercam pretty happily for years, though it does have its little idiosyncracies, but last year I started a project to remake a tabletop naval wargame called Seastrike, replacing the cardboard printed counters with ones made from sign-makers plastic laminate, which is a sheet of one colour with a thin surface layer of another colour. You just cut through the top layer to reveal the body of the plastic where you want it. However makercam proved to be a real PITA with it, primarily because of one bug, so I looked around for an alternative, didn't see one I liked. So I looked to see if anyone was developing or supporting makercam, but no-one was. I made all of the blue fleet, gritting my teeth, then decided to have a serious go at fixing makercam properly before tackling the red fleet and the grey/white submarines, and other bits and pieces.

Boy, did I fall through some rabbit hole! Looking through the source code and trying to understand how it all worked and came together was a real voyage of discovery! (I'm from Dundee, where the Discovery came from, and is now still berthed.) I found myself often using the phrase 'voyaging through strange seas of thought forever' except I replace voyaging with becalmed!

Anyway makercam's replacement SVGKam is pretty much done, and the current aspect I am working on is the SVG import/export functions, which I think are now working correctly. But in the process I was aware that XD16's SVG features were not behaving consistently, but I had been assuming it was doing things correctly and that any deficiencies were the fault of makercam/SVGKam. Makercam certainly had some serious issues with SVG, but SVGKam plays nicely with other SVG-apps, at least as far as sizing is concerned, but XD16 and now XD17, no they're both doing something I think they shouldn't.