Achieve crisp toon shadows

[bitter echo]

Hello there! I would like some ideas on how to achieve this crips shadow effect present in many games like in Boomerang Fu.

I have some ideas but I don't know how to get there...

• Applying some sort of filtering to the shadows via a Render Pass or Material
• Using Shadow Volumes / Stencil shadows?

I would love knowing your take on this effect! Thank you everyone!

[lapis girder]

They look like pretty ordinary shadows to me
Might not even be using any type of toon shading, just diffuse

[bitter echo]

https://www.youtube.com/watch?v=T9D_KYeu9RI They look super clean tho despite being a top down game 🤔 They would need a lot of shadow resolution for that, wouldn't they?

I'm looking to get these extremely crisp shadows, normal materials do not seem to do the trict as the shadow mapper is not good with that case, that's why I was looking for a Shadow Volume or Stencil shadows approach

But maybe with a filtering it can already work

[lapis girder]

Would have to be relatively high resolution, yes
If you look at the crates at 0:18 you can see individual pixels of the shadow shimmering, likely due to a shadow bias problem also characteristic to raster shadow casting

[bitter echo]

Oh I'm totally seeing that! So they are maybe just using a higher resolution? Isn't that very costly?

As the game is top down... Maybe I would have to up to 4K shadow resolution

[lapis girder]

Cost is relative

[lapis girder]

Note that shadow map resolution is only a part of the equation
It's relative to the shadow distance as well as cascades

Higher shadow distance, the lower the shadow resolution is relative to world space

[bitter echo]

Yep! The problem is that for top down I'm forced to have a lot of shadow distance

Because the game is seen from far away

It it somewhat improved with cascades

But still...

Also tried to mess around the camera far and near plane, which helped a bunch

[lapis girder]

I think near plane being as close to the world as possible should ensure the distance doesn't matter
Shadow distance is used instead of far plane, but far plane shouldn't be further away than needed, in any case

Unity 6 URP has higher quality shadow filtering methods
But if your shadow resolution is high enough and you happen to be using TAA it can smooth shadow edges too

[lapis girder]

Also, in this case your game window has a non-integer zoom level so even the box itself is choppy, so the shadow will be too
And the directional light is narrowly angled so the shadow pixels will be stretched and particularly aliased

If you need to have a very narrow light angle, rotating the directional light around its Z axis may align the shadowmap's pixels better with the most prominent object silhouettes, but it's a tradeoff

[bitter echo]

I see there are a lot of things I have to take into account 😅

I saw this Github project and I was excited there was a clear solution
https://github.com/rhedgeco/UnityShadowVolumeGenerator

[lapis girder]

Maybe it'd be viable to use a shadow volume instead, particularly as the perspective is fixed, number of objects is predictable and their polycounts low
But I don't know what the rendering cost of that will be, or if there are any solutions that can scale to that many objects out of the box

[bitter echo]

Yea that's the tradeoff... Also was wondering about the rendering cost

I think it was used long time ago but because the models were relatively low poly

[lapis girder]

Even mobile GPUs are getting good in terms of vram and parallelization, so I expect the overhead cost of features like shadowcasting is bigger than scaling the feature to have more resolution or more shadowcasting objects

Probably a case by case thing, and depends on what else you need to fit in your rendering budget

[bitter echo]

That's why also I thought of just creating a render pass or a shader that smooths out the shadow, as a tradeoff of having less consistent shadows

[bitter echo]

I see...

[lapis girder]

That's called shadow filtering, which URP already does

If you need to change it, it may be more efficient to modify the way URP implements it rather than doing it in a separate step afterwards