How to fill areas in an SVG drawing

[mike37510]

I'm working on a drawing mode for my CNC 3018 using a marker. I've managed to convert my drawing into GCode, but I'm running into an issue with filling areas. My SVG has filled regions, but when I convert it to GCode using this SVG to GCode generator, those areas aren't being filled.
Is that normal? Does the software not support filled areas, or did I do something wrong?

Thanks !

[coolbluewater]

Duplicate of #15. Sadly, there's no support for fills - I need this as well.

[sameer]

This is something I'd like to implement, but don't have a lot of context on -- I originally built this tool for pen plotters

What machines are you both using, and what kind of options are you expecting from a feature like this?

[coolbluewater]

The basic parameter is the pen width, which I think is not currently respected for strokes (outlines) either.
In svg a stroke is actually a 2d area owning to the fact that strokes have width.
Similarly, filled shapes are also 2d areas.

So we should think of svg as a collection of areas, not outlines.

Next, the plotter itself has a physical pen width, which we can think of as the diameter of a circle representing the pen tip.
So the areas represented by the svg need to be converted into plotting commands assuming the pen has this shape.

Obviously, if an area has a width that is less than the physical pen width it can't be drawn precisely, as the smallest drawable object has that width. So we can just trace the mid-line of that area with the pen. Thus a thin svg line represents a thin area which in gcode turns back into a line movement of the pen, which due to the pen's width results in a rectangle being drawn.

Now, for large filled areas there are many standard algorithms that can calculate the path the pen should traverse in order to completely fill the area. A second parameter (in addition to pen width) is the overlap percent. This is the amount that each stroke of the plotter should overlap other nearby strokes in order to ensure that there are no gaps due to the pen tip being circular, not square.

So, at a minimum the two parameters needed are pen width and overlap.
What we're describing is basically what a 3d printer's slicer does, but for just a single layer.

Although this may sound like a lot of work, I think it should be possible to make a lot of progress without a lot of code, particularly with a trusted AI assistant. Let us know if you are thinking of implementing this.

[sameer]

That makes sense, and agreed on the stroke handling -- it's a good idea to treat it as an area.

My only concern is making the tool too specific to pen plotters, it should still be usable with laser engravers / other CNC machines. So the pen width is the only parameter we'd need to figure out how to generalize. It being circular makes sense as is.