@woosh/meep-engine/src/core/geom/mat3/m3_cm_invert.js

Pure JavaScript game engine. Fully featured and production ready.

/**
 *
 * @param {Float32Array} out
 * @param {Float32Array} a
 */
export function m3_cm_invert(out, a) {
    // adapted from gl-matrix

    const a00 = a[0],
        a01 = a[1],
        a02 = a[2];

    const a10 = a[3],
        a11 = a[4],
        a12 = a[5];

    const a20 = a[6],
        a21 = a[7],
        a22 = a[8];

    const b01 = a22 * a11 - a12 * a21;
    const b11 = -a22 * a10 + a12 * a20;
    const b21 = a21 * a10 - a11 * a20;

    // Calculate the determinant
    let det = a00 * b01 + a01 * b11 + a02 * b21;

    if (!det) {
        return false;
    }

    det = 1.0 / det;

    out[0] = b01 * det;
    out[1] = (-a22 * a01 + a02 * a21) * det;
    out[2] = (a12 * a01 - a02 * a11) * det;
    out[3] = b11 * det;
    out[4] = (a22 * a00 - a02 * a20) * det;
    out[5] = (-a12 * a00 + a02 * a10) * det;
    out[6] = b21 * det;
    out[7] = (-a21 * a00 + a01 * a20) * det;
    out[8] = (a11 * a00 - a01 * a10) * det;

    return true;
}