i_overlay 6.0.0

Boolean Operations for 2D Polygons: Supports intersection, union, difference, xor, and self-intersections for all polygon varieties.
Documentation 
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use crate::core::link::OverlayLink;
use crate::segm::segment::{SUBJ_BOTH, SUBJ_BOTTOM, SUBJ_TOP};
use crate::string::graph::StringGraph;
use crate::string::rule::StringRule;
use alloc::vec::Vec;

impl OverlayLink {
    #[inline]
    pub(super) fn visit_fill(&self, fill: u8, node_id: usize, clockwise: bool) -> u8 {
        let is_a = self.a.id == node_id;
        let direct = self.a.point < self.b.point;
        let same = clockwise == direct;

        let mask = if is_a {
            if same { SUBJ_TOP } else { SUBJ_BOTTOM }
        } else if same {
            SUBJ_BOTTOM
        } else {
            SUBJ_TOP
        };

        fill & !mask
    }

    #[inline]
    pub(super) fn is_move_possible(&self, fill: u8, node_id: usize, clockwise: bool) -> bool {
        match fill {
            SUBJ_BOTH => return true,
            0 => return false,
            _ => {}
        }

        let is_a = self.a.id == node_id;
        let direct = self.a.point < self.b.point;
        let left = if direct {
            fill & SUBJ_TOP != 0
        } else {
            fill & SUBJ_BOTTOM != 0
        };

        is_a == (clockwise == left)
    }
}

impl StringGraph<'_> {
    #[inline(always)]
    pub(super) fn filter(&self, ext_rule: StringRule) -> Vec<u8> {
        match ext_rule {
            StringRule::Slice => self.filter_slice(),
        }
    }

    #[inline]
    fn filter_slice(&self) -> Vec<u8> {
        self.links.iter().map(|link| link.fill & SUBJ_BOTH).collect()
    }
}