title: How to prevent overlapping shadows when points are close together in coreplot?
body: <p>After the recent fix regarding rendering, <a href="https://stackoverflow.com/questions/13542456/how-to-draw-a-plot-symbol-shadow-behind-the-symbol-fill-in-coreplot">How to draw a plot symbol shadow behind the symbol fill in coreplot?</a> the shadows are drawn behind the point. </p>
  
  <p>However, core plot applies the shadows individually to each data point when using the delegate <code>-symbolForScatterPlot:recordIndex:</code> which results in overlapping shadows when data points are close together. For example, <img src="https://i.stack.imgur.com/ayy7Q.png" alt="shadow overlap when points are close together core-plot"></p>
  
  <p>Is it possible to avoid the shadow overlap of the perviously rendered data point? For example by rendering the shadows in a separate layer in a single sweep (or some other way)?</p>