_setSize() {
        if(this._shaderPass && this._shaderPass._isScenePass) {
            this._size = {
                width: this.renderer._boundingRect.width,
                height: this.renderer._boundingRect.height,
            };
        }
        else {
            this._size = {
                width: Math.min(this._maxSize.width, Math.max(this._minSize.width, this.renderer._boundingRect.width)),
                height: Math.min(this._maxSize.height, Math.max(this._minSize.height, this.renderer._boundingRect.height)),
            };
        }
    }
Sets our RenderTarget size based on its parent plane size
*