         computeEncoder.setComputePipelineState(checkerPipeline)
 
        // SET BUFFERDATA
-        let scaleOffset = 4 * sizeof(VertexData)
+        let scaleOffset = 4 * sizeof(PointData)
         computeEncoder.setBuffer(data, offset: scaleOffset, atIndex: 0) //offsetof(BufferData, rectScale)
 
         // SET TEXTURE

        //-----------------------------------------------------------
        let TexCoordDescriptor = MTLVertexAttributeDescriptor()
        TexCoordDescriptor.format = MTLVertexFormat.Float2
        TexCoordDescriptor.offset = sizeof(V2f)  // offsetof(VertexData, texCoord)
        TexCoordDescriptor.bufferIndex = 0
        //
        //-----------------------------------------------------------
        // Layout descriptor for Vertex Data.
        //-----------------------------------------------------------
        let LayoutDescriptor = MTLVertexBufferLayoutDescriptor()
        LayoutDescriptor.stride = sizeof(VertexData)
        LayoutDescriptor.stepFunction = MTLVertexStepFunction.PerVertex
        LayoutDescriptor.stepRate = 1
        //

        //-----------------------------------------------------------
        // vertex descriptor for Rect.
        //-----------------------------------------------------------
        let RectDescriptor = MTLVertexDescriptor()
        RectDescriptor.attributes[0] = PositionDescriptor

    let y:Float
}
//------------------------------------------------------------------------------------------
struct PointData
{
    let position:V2f
    let texCoord:V2f
