Transparent QoL part 1 - Refract & FresnelEquation Node

[skhiat]

Note: already reviewed [PR - splitting ShaderGraph only code]

Transparent Quality Of Life (part 1)

• RefractNode:
  Parametrize with eta which is the ratio of both IOR (Index Of Refraction) from incoming_medium (n_i) and outgoing_medium (n_o) eta == n_i/n_i. For instance from Air to Glass that would be 1.0/1.3333.
  If it's air-to-air interaction eta == 1:
  
  Otherwise:
  Air-glass interaction:
  

Note: the parameter incident is a vector which is from "source-to-surface" (for instance from eye-to-pixel):

We have 2 mode:

• Safe: Protect against NaN when a sqrt of a negative number which happen when we have glass-air interaction, at a specific angle we have no refraction but pure reflection which should be handle by Fresnel.
• CriticalAngle: Not protected the user should care of the negative case.

Fresnel node:

Note: already reviewed [PR - splitting ShaderGraph only code]

Add Scene Depth Difference for 3 format: {Linear01, Raw, Eye}:

UX review notes: changes the order of parameters

https://jira.unity3d.com/browse/HDRP-1600
https://jira.unity3d.com/browse/HDRP-1602
https://jira.unity3d.com/browse/HDRP-1603

ref:
#6201

https://jira.unity3d.com/browse/HDRP-1599

ref:
#6032

[kecho]

Approved: just make sure you move the docs to the hdrp package for hdrp specific nodes

[Vic-Cooper]

Modified docs.

[esmelusina]

As mentioned in Slack, We are holding off reviewing new feature requests until Jan at the earliest. We'll want a design and product review before we consider the PR.