New Alpha mode for Eevee: Alpha Stepped

Transparency is no doubt one of the biggest bottlenecks in a rasterizer.
The Alpha Hashed mode offers a nice balance between the properties of an opaque material (receiving ambient occlusion and screenspace shadows) while allowing the object to be transparent.
It lacks refraction, but that's the tradeoff.

Alpha Hashed shadows, however, tend to throw a very noisy light across the scene.
I would like to propose a different blend mode for materials, especially for shadow casting objects:
Shadow Stepped.

Let's look at the following example:

This is the result of an invisible shadow card in between the light and the surface, which results in this caustic effect.
As you can see, even at 128 samples, it's quite noisy.

To create a proof-of-concept, I animated the "Clip Threshold" of the shadow card, from 0.0 to 1.0. I set the render samples to 1, and shook the camera and lights to simulate Anti Aliasing.

Then, I averaged out the results:

At 16 samples, the shadow still appears a bit blocky: But at 32, it's nice and smooth.

Much better than the original hashed version!