 
 class VGridVisorMetal:MTKView
 {
-    private weak var controller:CGridVisor!
+    private weak var controller:CGridVisor?
     private let samplerState:MTLSamplerState
     private let commandQueue:MTLCommandQueue
     private let pipelineState:MTLRenderPipelineState

        renderEncoder.setFragmentSamplerState(
            samplerState,
            at:MetalConstants.kFragmentSamplerIndex)
        controller.modelRender?.render(renderEncoder:renderEncoder)
        
        renderEncoder.endEncoding()
        commandBuffer.present(drawable)

    override func draw()
    {
        super.draw()
        controller?.viewGridVisor.viewTarget.update()
        
        guard
            
