{
	A hatch pattern in xy plane.

	A1 gives aspect ratio of hatch (y/x).
	A2 gives width of hatch line.
	A3 gives brightness of hatch line.
	X hatch width is 1.
}

xyhatch = if(or(xhatch,yhatch), A3, 1);

xhatch = A2 - frac(Px+A2/2);
yhatch = A2 - frac(Py/A1+A2/2);
