The Shading node refers to material properties and light  and not to shadows. To enable shading you need a light in your comp and to turn the Shading on the Main Stardust effect.
You can get more control over shading with the Shading node,  like selecting the lights, for Rectangles and Textured particles you can set Specular, Environment and more.
If you experience any issue with that please send us an email.

Wow, I totally missed the Shading check box in the main Stardust panel. That explains things.
I do notice some weird behavior from Shadow Properties in the Particle tab. First of all, they are always circles, even if the Particle shape is set to rectangle or cloud. That seems wrong.
I do find the 2D nature of the drop shadows a little weird, considering they kinda move according to the light, but kinda don’t. I find it somewhat powerful to have those 2D-ish controls, but also a little bit “incorrect.” For example, the uniform “Distance” for shadows kinda works for drop shadow stylized stuff, but technically the distance should depend on the location of the light and how the shadows hit on the other particles or not. Right? I kinda dig the option of the 2D nature of this and having such controls, but I’d also love to see “3D accurate” options as well for Shadows.
Just to take this a step further, is there any intention to add self-shading to the particles themselves? It’d be great if they’d have shadows and highlights based on the lights, especially if we can control the actual specular/diffuse/etc with the Shading settings. (I realize some of what I’m actually after might be doable in a fake 2D way by building the right network, and I looove the node-based approach you’ve got going — so powerful — but I’m curious what the plans are in terms of light-accurate 3D shading.)
 
Thanks for the speedy reply!
Best,
zane

Hi Zane,
Its always a balance between speed and accuracy, we will have more options with future updates. 

Thanks for the feedback,
Aharon
superluminal

Aharon,
 
Thanks for the clarification. I get that you want to keep things speedy, and I definitely agree. Maybe there are some shortcuts for cheating what I’m after.
 
BTW, I’m not actually looking for a super realistic rendering. In fact, I’m ultimately looking for a very simple two-tone anime look, in this particular case. And I’ve managed to get past the limitation of the circular drop shadow easily enough by using your brilliant node-network to simply hook the Emitter into a second Particle chain with a Transform to offset it. Unfortunately, I can’t quite get the Scale in the Transform to behave how I imagine it would. I’d like for the “shadowed” copy to be offset a smaller amount as the particles are small than they are as they get larger, but Scale doesn’t really do that.
 
Any suggestions? Could there be a Transform Over Life? Or some other way to accomplish this? The Drop Shadows kinda have the same limitation. Ideally you’d have their Distance be dependent on their size or something? (As an example, look at the bottom of the smoke plume here: https://ibb.co/c4SRaa …Ideally there wouldn’t be such a gap at the bottom when the particles are small. The gap would vary over time or size.)
 
Anyway, I’m loving this filter so far, and can already imagine many incredible ways we can use it in production here.
 
Best,
zane
 

Has there been any developments on the round (circle) shadows? I have a square particle system and the shadows are round. Will this be corrected in the coming update on the 29th September 2017? or October for PC?
Thanks!
Joe

Hi Joe, Could you please send me an email with a the affected comp,  maybe there is a workaround.  support@superluminal.tv
Aharon