The existing scanline method works just fine, and only needs the points
to be available as floats.
This commit reverts the complex polygon mitigation, and instead fixes
the rasterization process to avoid generating complex polygons because
of precision issues.
This allows the painter to render filled complex shapes better, by
constructing a path graph for (interesting) intersecting lines and
omitting lines from the containing segments if they are detected
to take no part in defining the edges of a shape.
This approach would still fail if there are multiple logical shapes
that are confined to the collection of lines.
For instance, two polygons intersecting each other in a way that one
vertex of polygon A ends up inside polygon B.
we would detect that polygon A's edges are part of the shape
(technically correct) even though they are not a part of polygon B at
all.
There are some imperfections with intersecting edges (because the main
algorithm used is scanline, and that is not geared towards drawing
complex shapes), however, it behaves mostly fine for normal use :^)
This will be used to implement painting of 2D paths. This first patch
adds support for line_to(), move_to() and close().
It will try to have the same semantics as the HTML <canvas> element.
To stroke a Path, simply pass it to Painter::stroke_path().
blit_filtered() can be used to easily implement per-pixel filtered blit
functions. All you need to do is provide a callback that can compute
the Color for each pixel based on the original Color.
