NAME

Graphics::Penplotter::GcodeXY::Hatch - Scanline hatch-fill for GcodeXY paths

SYNOPSIS

$g->sethatchsep(2);        # 2-unit spacing between hatch lines
$g->sethatchangle(45);     # 45-degree hatch lines (default: 0 = horizontal)
$g->polygon(0,0, 10,0, 10,10, 0,10, 0,0);
$g->strokefill();          # hatch-fill the polygon and stroke it

DESCRIPTION

A Role::Tiny role providing scanline hatch-fill at any angle for Graphics::Penplotter::GcodeXY.

The entry points are sethatchsep, sethatchangle, and strokefill. The internal method _dohatching is also composed in so that Graphics::Penplotter::GcodeXY::Font's _doglyphs can call it via $self->_dohatching() when rendering filled text.

Algorithm

_dohatching works in a rotated hatch space where the scanlines are always horizontal, regardless of the requested hatchangle:

1. All psegments endpoints are rotated by -hatchangle into hatch space and stored in a temporary array, which is swapped into $self->{psegments}.

2. The bounding box, scanline sweep, intersection tests (_getsegintersect), and vertex deduplication (_identical, _sameside) all run unchanged on the rotated copy, they always see horizontal scanlines and need no modification.

3. Before each hatch segment is recorded via _addhsegmentpath, its endpoints are rotated back by +hatchangle into drawing space.

4. The original psegments are restored before _flushHsegments writes the gcode.

METHODS

sethatchsep($sep)

Set the spacing between hatch lines in the current drawing unit.

sethatchangle($degrees)

Set the angle of the hatch lines in degrees. 0 (the default) gives horizontal lines; 90 gives vertical lines; 45 gives diagonal lines. Positive angles rotate the lines counter-clockwise.

strokefill()

Hatch-fill the current path at the current angle and spacing, then flush the segment queue and clear the path.

REQUIRED METHODS

_croak, gsave, grestore, _getsegintersect, _addtopage, _flushPsegments, newpath.

AUTHOR

Albert Koelmans (albert.koelmans@googlemail.com)

LICENSE

Same terms as Perl itself.