cables_dev/cables/src/core/cg/cg_matrixstack.js

const MatrixStack = function ()
{
    this._arr = [mat4.create()];
    this._index = 0;
    this.stateCounter = 0;
};

MatrixStack.prototype.push = function (m)
{
    this._index++;
    this.stateCounter++;

    if (this._index == this._arr.length)
    {
        const copy = mat4.create();
        this._arr.push(copy);
    }

    mat4.copy(this._arr[this._index], m || this._arr[this._index - 1]);

    return this._arr[this._index];
};

MatrixStack.prototype.pop = function ()
{
    this.stateCounter++;

    this._index--;
    if (this._index < 0) this._index = 0;

    return this._arr[this._index];
};

MatrixStack.prototype.length = function ()
{
    return this._index;
};

export { MatrixStack };