_initCurtains() {
        this.planes = [];
        this.renderTargets = [];
        this.shaderPasses = [];

        // init webgl context
        this._initRenderer();

        if(!this.gl) return;

        // scroll
        this._initScroll();

        // sizes
        this._setSize();

        // event listeners
        this._addListeners();

        // we are ready to go
        this.container.appendChild(this.canvas);

        // watermark
        console.log("curtains.js - v" + version);

        // start rendering
        this._animationFrameID = null;
        if(this._autoRender) {
            this._animate();
        }
    }
Initialize everything that the class will need: WebGL renderer, scroll manager, sizes, listeners
     Then starts our animation frame loop if needed
*