@woosh/meep-engine/src/engine/graphics/geometry/MikkT/v3_scale_dot_sub_normalize.js

Pure JavaScript game engine. Fully featured and production ready.

import { vec3 } from "gl-matrix";
import { v3_length } from "../../../../core/geom/vec3/v3_length.js";
import { v3_dot } from "../../../../core/geom/vec3/v3_dot.js";

/**
 * executes following formula: v1 - v0*( dot(v0,v1) )
 * @param {vec3} out
 * @param {vec3} v0
 * @param {vec3} v1
 */
export function v3_scale_dot_sub_normalize(out, v0, v1) {
    const v0x = v0[0];
    const v0y = v0[1];
    const v0z = v0[2];

    const v1x = v1[0];
    const v1y = v1[1];
    const v1z = v1[2];

    // dot product
    const _dot = v3_dot(v0x, v0y, v0z, v1x, v1y, v1z);

    // scale
    const _x0 = v0x * _dot;
    const _y0 = v0y * _dot;
    const _z0 = v0z * _dot;

    // subtract
    const _x1 = v1x - _x0;
    const _z1 = v1z - _z0;
    const _y1 = v1y - _y0;

    // "safe" normalization
    const len = v3_length(_x1, _y1, _z1);

    if (len !== 0) {

        const m = 1 / len;

        out[0] = _x1 * m;
        out[1] = _y1 * m;
        out[2] = _z1 * m;

    } else {

        out[0] = _x1;
        out[1] = _y1;
        out[2] = _z1;

    }

}