Shockwave Material?

The Vman

So I'm trying to recreate the distinctive expanding ring of dust and debris being kicked up from an explosion.
https://www.youtube.com/watch?v=B7U8-CqhYu0

I don't just want to do it with a flat particle that grows in size, as that wouldn't properly react to surfaces of different angles and shapes. I was wondering if it'd be possible to create a material that renders on the cross section of geometry as it intersects. That way, I can create an expanding sphere from an explosion, and any geometry that intersects with the sphere has a texture overlaid on top of it. Like this:



In an old thread that talked about the technical specs of Wind Waker, they demonstrated what looked like the effect I want, used for faux lighting.



Any help with this would be greatly appreciated!

Vailias

Try starting with a translucent material and a depth fade node. The default output should give you a greyscale output that fades your object as it gets in contact with other objects, but if you invert that and tinker with it a bit, I'll bet you can get an effect where it does something like what you're after.

The Vman

I don't really see how that'd work. I'm not sure how I'd "invert" depth fade, and even if I did I doubt it'd give me a cross section of the geometry.

Vailias

Cross section no. but at least an edge effect. For a cross section you'd need to do some slicing, or other intersection that would need some custom render pipeline support, as in the wind waker stencil buffer tricks, or to have every material in the scene be able to react to explosions so the shading effect would be applied to the material on the walls/environment rather than to the explosion effect and geometry.

However a depth fade could be used to show only the surface of a mesh close to another mesh, so if your mesh is the right size and shape, and in motion, you'll get something that can be part of an overall shockwave effect. 
You're likely going to want to have this be a multi part thing, with the mesh part of the wave being one bit, a leading edge particle system and possibly other parts depending on scale and speed of transmission. 

see below for examples:  and I'm sure you could even do better with more than a few minutes spent on it.

The Vman

Ahh, I see. It's not quite the effect I'm looking for but it's certainly interesting looking. I'll play around with that.
Though if anyone knows how I could do a cross section that'd still be good to know.

passerby

You might want to try the SphereMask node it should do what you want