For today's news post, our Tech Art Lead Saveun has written about using the Subsurface Refraction technology in Path of Exile. Check it out below!

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Hey, I’m Saveun, Tech Art Lead at Grinding Gear Games and this is a post about my second most favorite piece of rendering tech we have, it’s a shader we refer to as Subsurface Refraction, how it came about and how we use it.

Unsure when exactly we started looking into it but I know this was doing the rounds internally. Focusing on the crystal here, we were trying to pull off that same look. Was cool seeing artists at the time putting their own examples together for live content with all your standard techniques.

I ended up following this crystal creation quite close and well when we put it in-game the visual aesthetic versus rendering cost wasn’t ideal.


In steps Alexander aka Dr Alex, some of you may have seen his talk during ExileCon. In the clip Alexander gives a more detailed explanation of the shader itself.

So now we have something, keep in mind this thing doesn’t come back 100% usable. There is a back and forth finalising texture maps as well as efficient texture packing in some cases to make this thing the best most performant thing it can be.

These Bloodbags were the first asset to get the full Subsurface Refraction treatment in all their pulsing glory:


And of course some Legion crystals, courtesy of Felipe.


Like many things Subsurface Refraction continues to evolve, as we move forward with new content we’ve adopted it fully for most ice.


And to wrap this post up one of the most recent example:


Cheers for making it to the end. Here’s some more Path of Exile content I’ve worked on for those interested.

Till next time.
-Saveun