DOTS minimal picking support (Graphics part)

[vincent-breysse]

Purpose of this PR

This PR implements URP/HDRP minimal picking support for DOTS. This is intended to be on parity with Hybrid Renderer V2 picking.

The basic idea here is to define a new shader for URP/HDRP and use that only when rendering the BatchRendererGroup objects for the picking (renders object instanceIDs in a tiny 4x4 texture, then read it back from CPU).
Of course, it does not fully work with any kind of vertex deformation (including tessellation) and decals.
To put it simply: Picking "hitbox" = Mesh transformed by LocalToWorld matrix

This PR does not have any impact on the current GameObject picking.

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Filtered diff for URP/HDRP reviewers here

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Testing status

• HDRP validated by @TomasKiniulis
• URP validated by @cinight
• Yamato HDRP green except for some unrelated failing tests
• Yamato URP green except for some unrelated failing tests

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Note to reviewers

There are some changes included in the ShaderGraph and VFX Graph packages, but they are not mine. Those changes are the result of an auto-upgrade performed when opening the HybridURP/HDRP test projects with recent trunk.

[sebastienlagarde]

Hey, so for HDRP there is something wrong, or maybe I do'nt understand the PR.

The current code don't work with vertex deformation or tessellation in SG or depth offset.
And overall don't work with SG.

I am not sure to understand why you need to add this file BRGPicking.hlsl with vert and frag definition.

My understanding is what you really want is simply to reuse the current scene picking pass we have declare everywhere, and simply adjust a bit the code with #ifdef DOTS_INSTANCING
to call this specific function LoadObjectToWorldMatrixBRGPicking();

this function is the main change from what I get.
Let's setup a call or a chat will be easier to see how to solve that (or if I haven't understand the purpose)

[sebastienlagarde]

Tessellated object picking is only partially implemented. The picking "hitbox" is basically the same as the non-tessellated >version of the object, which means that trying to pick displaced triangles does not work.

ok I should have read the description, but same problem is true for vertex deformation. Let's talk can be easily fixed.

[phi-lira]

Approved with some comments.