ShaderGraph not compatible with raytracing?

Unity Engine
,
1

Using latest beta (2020.2.0b8)
An HDRP shader graph I have throws an error with some raytracing elements turned on:
(possibly path tracing)

Shader error in 'Shader Graphs/RotatedGraphNormal': Compilation failed [0x80004005 - Unknown error.] ':6833:27: warning: implicit truncation of vector type
                    float normalSample = Texture.Sample(Sampler, UV);
                          ^
:6834:27: warning: implicit truncation of vector type
                    float uSample = Texture.Sample(Sampler, offsetU);
                          ^
:6835:27: warning: implicit truncation of vector type
                    float vSample = Texture.Sample(Sampler, offsetV);
                          ^
error: validation errors
at 0x297b612d810 inside block #0 of function ?ClosestHitMain@@YAXURayIntersection@@UAttributeData@@@Z Opcode Sample not valid in shader model lib_6_3(closesthit)
2

What HDRP version are you using ? 10.1.0 ?

Can you share your graph so we can understand which node is this coming from ?

3

10.0.0 of everything is installed with latest beta - should I update packages to 10.1?

Edit: Fails on Normal from Texture Node

6462046–724765–RotatedGraphNormal.zip (5.04 KB)

4

Managed to repro your issue, it’s because the Path Tracer (and ray tracing effects in general) don’t support derivatives which the node Normal from textures relies upon. (It’s being added in the documentation for the next package).

So, updating won’t solve your issue but just removing the node solves it, you can import a normal map instead of creating it from the texture in the SG.

I’ll see if we can fail more gracefully than this when something is not supported tho

5

OK thanks - maybe I can convert a heightmap to normal map (textures are procedural) in code to circumvent this node

6

What I observed is that any material with normal map results in black in ray-traced reflections, is that expected?