@woosh/meep-engine/src/core/geom/3d/tetrahedra/tetrahedron_contains_point.js

Pure JavaScript game engine. Fully featured and production ready.

import { orient3d_fast } from "../plane/orient3d_fast.js";

/**
 * Containment test, whether tetrahedron defined by A,B,C,D contains point E or not
 * Implemented using planar tests on each of side of the tetrahedron
 *
 * NOTE:    similar to https://gitlab.onelab.info/gmsh/gmsh/-/blob/master/contrib/hxt/tetMesh/src/HXTSPR.c
 *          We skip identity checks and bounding box checks. Identity is a waste of time when building tetrahedral mesh,
 *          since each inserted point will be new to the mesh, box checks are not relevant as we don't track those
 *
 * @param {number[]} points
 * @param {number} a
 * @param {number} b
 * @param {number} c
 * @param {number} d
 * @param {number} e
 * @returns {boolean}
 */
export function tetrahedron_contains_point(points, a, b, c, d, e) {
    return !(
        orient3d_fast(points, b, d, c, e) > 0
        || orient3d_fast(points, c, d, a, e) > 0
        || orient3d_fast(points, d, b, a, e) > 0
        || orient3d_fast(points, a, b, c, e) > 0
    );
}