I want to get off Mr. Fresnel's wild ride

[aevyrie]

Objective

• Unbreak fresnel.
• Fix a small math error.

Solution

• Don't be stupid.

Testing

main: fresnel missing entirely

Roughness dependent fresnel: still too bright

Note how this violates the furnace test (reflection is brighter (has more energy) than what it is reflecting):

Fixed existing, boring fresnel: juuuuust right

and this one does not

Bistro

More fresnel than the 0.18 release post, but it seems like a correct amount, considering it lacks any specular occlusion.

Release post

This PR (light intensities different, doesn't affect fresnel)

This PR + SSR - fresnel is further occluded where it should be

As soon as you add specular occlusion with SSR, the fresnel starts to make sense again, occluded objects no longer reflect the envmap in their fresnel reflection. Note the awnings here look bright in shadow because they are catching the envmap, until you turn on SSR which tones this down with specular occlusion.

Note that the fresnel is actually helpful here - without it we wouldn't get this soft reflection of the scooter against the sky (env) on the pavers:

[alice-i-cecile]

Do we want to try the same comparison but with the Blender sphere reference scene? Or is that not suitable for examining fresnel specifically?

[aevyrie]

The main reference we have for this is the gray furnace test, which we seem to be passing still, without completely deleting fresnel.