[10.x.x] Screen Space Ambient Occlusion (Part 1&2)

[ellioman]

Purpose of this PR

This is the first and second part of an SSAO implementation for URP.

SSAO will be added incrementally to the master branch. The plan is as follows:

• Part-1: SSAO with Depth only mode.
• Part-2: SSAO with Depth Normals mode, DepthNormal prepass and ConfigureInputs() for ScriptableRenderPasses
• Part-3: SSAO with Deferred mode
• Part-4: SSAO with Volume Framework support.

Known issues

• SSAO doesn't work with dynamic resolution as we need to update the _ScreenParams parameter sent to our shaders. This will will be fixed in another PR.

This PR adds the following:

• Removes the 8 renderer limit in the URP Asset
• Adds SSAO render feature and editor script for that
• Adds new Shader keyword _SCREEN_SPACE_OCCLUSION
• Adds a virtual ScriptableRenderFeature.Dispose() function which is invoked during ScriptableRenderer.Dispose()
• Adds normalizedScreenSpaceUV parameter to the InputData struct
• Adds a DepthNormal pass in URP Shaders and a Depth Normals Prepass
• Adds ConfigureInput() function to ScriptableRenderPasses
• Makes the ForwardRenderer check inputs set by render passes for input requirements
• Adds Universal Graphics Test scene: 142_SSAO_DepthNormal_Projection
• Adds Universal Graphics Test scene: 143_SSAO_DepthNormal_Orthographic

---

Checklist for PR maker

• Have you added a backport label (if needed)? For example, the need-backport-2019.3 label. After you backport the PR, the label changes to backported-2019.3.
• Have you updated the changelog? Each package has a CHANGELOG.md file.
• Have you updated or added the documentation for your PR? When you add a new feature, change a property name, or change the behavior of a feature, it's best practice to include related documentation changes in the same PR.
• Have you added a graphic test for your PR (if needed)? When you add a new feature, or discover a bug that tests don't cover, please add a graphic test.

---

Testing status

Manual Tests: What did you do?

• Opened test project + Run graphic tests locally
• Built a player
• Checked new UI names with UX convention
• Tested UI multi-edition + Undo/Redo + Prefab overrides + Alignment in Preset
• C# and shader warnings (supress shader cache to see them)
• Checked new resources path for the reloader (in devloper mode, you have a button at end of resources that check the pathes)
• Other:

Automated Tests: What did you setup? (Add a screenshot or the reference image of the test please)

Yamato: (Select your branch):

[erikabar]

Performance in URP SSAO is generally better compared to Builtin PPv2 SSAO, but we will need to take a deep dive into performance after this PR. Performance results can be found here: https://docs.google.com/spreadsheets/d/1BwQxOJXhzk4X6GeSvPqUlbuzKSFYtH_N_oIpxKsvtbg/edit#gid=650080094&range=A1:D1

[hybridherbst]

@ellioman great that this finally landed - would you mind explaining why you removed the backport labels? A lot of people are really hoping that this will land in 7.x as you know :)