                 
                 createRenderPass(commandBuffer,
                     pipeline:  _blurPipelineStates[1],
-                    vertexBuffers: passthroughParameters,
+                    vertexIndex: 0,
                     fragmentBuffers: parameters,
                     sourceTextures: [_intermediateTextures[0]],
                     descriptor: _blurDescriptor,

            1.0,   1.0,  1.0, 1.0]
        
        // set up vertex buffer
        dataSize = dataPortraitUpsideDown.count * sizeofValue(dataPortraitUpsideDown[0]) // 1
        _vertexBuffers[.PortraitUpsideDown] = (_device.newBufferWithBytes(dataPortraitUpsideDown, length: dataSize, options: nil),0)
        
        // create default shader library
        _shaderLibrary = _device.newDefaultLibrary()!

    private var _controller:UIViewController! = nil
    
    lazy private var _device = MTLCreateSystemDefaultDevice()
    lazy private var _vertexStart = [UIInterfaceOrientation : Int]()

    private var _vertexBuffer:MTLBuffer! = nil
    private var _filterArgs:MetalBufferArray<FilterBuffer>! = nil
    private var _colorArgs:MetalBufferArray<ColorBuffer>! = nil
    private var _blurArgs:MetalBufferArray<BlurBuffer>? = nil
