function MStack() {
      this.mats = [];
      this.size = 0;
      for (var i = 0; i < 20; i++) {
        this.mats.push(Mat3.create([0, 0, 0, 0, 0, 0, 0, 0, 0]));
      }
    }
Destroys the renderer and cleans up resources.
@param {Array<Particle>} particles - The particles to clean up.