extruded_polygon_region()

std::function< bool(glm::vec3)> MayaFlux::Kinesis::extruded_polygon_region ( std::span< const glm::vec2 >  footprint, float  y_min, float  y_max  )

inline

Containment test for a vertically extruded 2D polygon.

The footprint is tested with the winding number algorithm in the XZ plane. The Y axis is the vertical: the point must satisfy y_min <= p.y <= y_max. Covers authored rooms, columns, corridors where the cross-section is constant along Y.

Parameters

footprint	Polygon vertices in XZ. Copied into closure.
y_min	Lower Y bound (inclusive).
y_max	Upper Y bound (inclusive).

Definition at line 354 of file Bounds.hpp.

{
    std::vector<glm::vec2> verts(footprint.begin(), footprint.end());
    return [verts = std::move(verts), y_min, y_max](const glm::vec3& p) {
        if (p.y < y_min || p.y > y_max)
            return false;
        glm::vec2 q { p.x, p.z };
        int winding = 0;
        const size_t n = verts.size();
        for (size_t i = 0; i < n; ++i) {
            glm::vec2 a = verts[i];
            glm::vec2 b = verts[(i + 1) % n];
            if (a.y <= q.y) {
                if (b.y > q.y) {
                    float cross = (b.x - a.x) * (q.y - a.y)
                        - (b.y - a.y) * (q.x - a.x);
                    if (cross > 0.0F)
                        ++winding;
                }
            } else {
                if (b.y <= q.y) {
                    float cross = (b.x - a.x) * (q.y - a.y)
                        - (b.y - a.y) * (q.x - a.x);
                    if (cross < 0.0F)
                        --winding;
                }
            }
        }
        return winding != 0;
    };
}

References a, b, and q.