Function point_to_segment_dist_sq

nodedb-spatial/src/predicates/edge.rs:110–132

Minimum squared distance from a point to a line segment. Returns the squared distance (avoid sqrt for comparison purposes).

(pt: [f64; 2], seg_a: [f64; 2], seg_b: [f64; 2])

///
/// Returns the squared distance (avoid sqrt for comparison purposes).
pub fn point_to_segment_dist_sq(pt: [f64; 2], seg_a: [f64; 2], seg_b: [f64; 2]) -> f64 {
    let dx = seg_b[0] - seg_a[0];
    let dy = seg_b[1] - seg_a[1];
    let len_sq = dx * dx + dy * dy;

    if len_sq < 1e-20 {
        // Degenerate segment (zero length) — distance to point.
        let ex = pt[0] - seg_a[0];
        let ey = pt[1] - seg_a[1];
        return ex * ex + ey * ey;
    }

    // Project pt onto the line, clamped to [0, 1].
    let t = ((pt[0] - seg_a[0]) * dx + (pt[1] - seg_a[1]) * dy) / len_sq;
    let t = t.clamp(0.0, 1.0);

    let proj_x = seg_a[0] + t * dx;
    let proj_y = seg_a[1] + t * dy;

    let ex = pt[0] - proj_x;
    let ey = pt[1] - proj_y;
    ex * ex + ey * ey
}

/// Minimum squared distance between two line segments.
pub fn segment_to_segment_dist_sq(a1: [f64; 2], a2: [f64; 2], b1: [f64; 2], b2: [f64; 2]) -> f64 {