Marker code of the 'scatter-3D' example

Thanks for your book! The figures are amazing. Since I am working in 3D and have to play around with point clouds a lot, I really want to know how the 'Scatter-3D' exmaple is made. It seems the core part is the custom marker. The marker's fading shadow rings create a beautiful effect of 3D shading. Can you share the code for creating this example? Thanks a lot!