calculation of axes

I just tried to export some of my fonts as variable fonts using fontmake.

At least partially, it tries to determine the axes by looking at the instances. It prints this: INFO:fontTools.varLib:Axes: ... that contains numbers from the instances. And if those are not siting at the master location, it gives an error later on: assert base_idx is not None, "Base master not found; no master at default location?"

So the axes should always be computed from the masters (and Virtual Masters).

[schriftgestalt]

Virtuel masters are there to open the axis range if there is no real master to do so. That is used with brace layers. That way you can implement ascender/descender axes without the need to duplicate the whole font.

{
	name = "Virtual Master";
	value = (
		{
			Axis = Weight;
			Location = 100;
		},
		{
			Axis = Width;
			Location = 200;
		}
	);
}

[schriftgestalt]

The original issue is still there. The virtual masters are just an illustration not an actual problem.