How do I set particles to shadow other particles?

I’m trying to create self shadowing on particles, and I cant seem to get it working correctly.
ex:

we followed this: https://docs.unrealengine.com/latest/INT/Resources/ContentExamples/EffectsGallery/1_H/index.html
and messed around with all sorts of settings and particles always shade based on camera angle to the particles and light. How can I get particles to shade one another based on the direction the light hits them like the images in the first link show?

Hey xdbxdbx -

I also saw what The Jamsh and DieByZer0 have mentioned here on the forums, Trying to get particle shadows to apply to other particles. - Rendering - Unreal Engine Forums, but I would mention that you want to make sure that depending on your normals you can increase their influence with the Translucency Directional Lighting Intensity which would help a little. For the task you mention on the forums. You probably will want to look into MacroUV to achieve the look you want but it will be an effect applied to the particle system which will emulate the look you are wanting to achieve.

Thank You

Eric Ketchum