@woosh/meep-engine/src/core/geom/3d/line/line3_computeSegmentPointDistance_sqr.js

Pure JavaScript game engine. Fully featured and production ready.

import { v3_distance_sqr } from "../../vec3/v3_distance_sqr.js";
import { clamp01 } from "../../../math/clamp01.js";

/**
 * Computes shortest distance between a line segment(defined by 2 points) and a point
 * @param {number} x0
 * @param {number} y0
 * @param {number} z0
 * @param {number} x1
 * @param {number} y1
 * @param {number} z1
 * @param {number} px
 * @param {number} py
 * @param {number} pz
 */
export function line3_computeSegmentPointDistance_sqr(x0, y0, z0, x1, y1, z1, px, py, pz) {
    // get line delta
    const line_delta_x = x1 - x0;
    const line_delta_y = y1 - y0;
    const line_delta_z = z1 - z0;

    // find closest point
    const sp0_x = px - x0;
    const sp0_y = py - y0;
    const sp0_z = pz - z0;

    //
    const d2 = line_delta_x * line_delta_x + line_delta_y * line_delta_y + line_delta_z * line_delta_z;

    const d3 = line_delta_x * sp0_x + line_delta_y * sp0_y + line_delta_z * sp0_z;

    const t = clamp01(d3 / d2);

    // compute point on the line
    const lp_x = line_delta_x * t + x0;
    const lp_y = line_delta_y * t + y0;
    const lp_z = line_delta_z * t + z0;

    // compute distance from the point in question to the point on the line
    return v3_distance_sqr(px, py, pz, lp_x, lp_y, lp_z);
}