Terrain instancing incompatible with tessellation/surface shaders [1111579]

Had texture arrays not been broken through the entire 2018.3 beta, I might have caught this earlier. But basically the new instancing system used for terrain is incompatible with surface shader tessellation. It will complain that the input (inout) parameter to the displacement function is not fully initialized, because the instance ID is not initialized before being passed to this function.

Bug id: 1111579

 

@jbooth Did you manage to solve the issue finally?

 

Nope, not something that can be worked around. Unity seems to be happily ignoring it too, since they are trying to move away from surface shaders.

 

Oh ok, thanks for the answer Jason. Actually the current state of surface shaders are somewhat ambiguous, because Shader Graph is only available in SRPs, and normal pipeline still uses surface shaders and is the same in the latest versions yet we hear they will drop them soon.

Shader Graph is what we need as developers and also normal users but what about all these missing features in normal pipeline!

 

It still breaks on 2018.4.2f1 LTS, though with different errors:

Shader error in 'MicroSplat/Example_Tessellation': Unsupported dynamic indexing scheme on constant buffer vars. (on metal)

Metal: Error creating pipeline state (MicroSplat/Example_Tessellation): Link failed: fragment input user(SV_InstanceID0) was not found in vertex shader outputs
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Somehow I missed that response but will respond with this there as well, along with a new repro.