Use homogeneous coordinates to reduce floating point error when computing the intersection of self-intersecting line segments.
Partially addresses
@@ -342,7 +342,8 @@ impl<'a> Partitioner<'a> {
self.emit_b_quads_around_active_edge(upper_active_edge_index, crossing_point.x);
self.emit_b_quads_around_active_edge(lower_active_edge_index, crossing_point.x);
} else {
- debug!("warning: swapped active edges {} & {} without finding intersection",
+ warn!("swapped active edges {} & {} without finding intersection; rendering \
+ will probably be incorrect",
upper_active_edge_index,
lower_active_edge_index);
}
@@ -1009,7 +1010,8 @@ impl<'a> Partitioner<'a> {
let (lower_line, _) =
Line::new(lower_left_vertex_position,
lower_right_endpoint_position).subdivide_at_x(max_x);
- upper_line.intersect_with_line(&lower_line)
+ // Use `intersect_at_infinity()` to reduce floating point error.
+ upper_line.intersect_at_infinity(&lower_line)
}
(upper_control_point_vertex_index, u32::MAX) => {
