Single Pass Stereo Rendering is not supported by LWRP Terrain shader

Hi, it seams Unity team forgot to support Single Pass Stereo Rendering for LWRP TerrainLit shader. Other LWRP shaders have it, even some "internal" shaders of Terrain shader (like WavingGrass) have support for Single Pass Stereo.

If you want to reproduce - use LWRP VR template, put a terrain and any 3D model on scene and run on device - right eye picture will have some kind of "shadow object" behind 3D model in the part where model overlaps terrain (at least on GearVR). Sorry for terminology, I'm totally new to Unity, shaders, 3D modelling etc...

So I made a fix based on this Unity doc (check Custom shaders section) and code from other Lit shaders inside LWRP package.

You need to add one line to struct Varyings in TerrainDetailLit.shader file:
UNITY_VERTEX_INPUT_INSTANCE_ID
and several lines to file TerrainLitPasses.hlsl:
1. Two lines to struct Varyings
UNITY_VERTEX_INPUT_INSTANCE_ID
UNITY_VERTEX_OUTPUT_STEREO
2. Two lines
UNITY_TRANSFER_INSTANCE_ID(v, o);
UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
to method Varyings SplatmapVert(Attributes v) right after line
UNITY_SETUP_INSTANCE_ID(v);
3. Two lines
UNITY_SETUP_INSTANCE_ID(IN);
UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(IN);
in the very beginning of method half4 SplatmapFragment(Varyings IN) : SV_TARGET

This totally solved the issue for me.
Attached are modified files for your convenience. Replace corresponding files in <<PathToYourProject>>\Library\PackageCache\com.unity.render-pipelines.lightweight@5.13.0\Shaders\Terrain\ folder.

 

Thanks kivinm, that was very helpful!

 

Is there a permanent fix for this issue? Because Libary folder gets regenerated every time Unity is launched and you need to repeat shader replacement process every time....

 

Sort of fixes it. Baked shadows are rendered in one eye, but not the other.
Anyone know if there is a permanent fix yet?

 

Would be interested to see this, never had this issue myself but is worth reporting as a bug

 

This is still an issue with the latest 2019.3.0f5 and Universal RP 7.1.7

 

its fixed in 7.2 version of URP

 

com.unity.render-pipelines.universal\Runtime\Materials\TerrainLit

^ that's the one you need when using 7.2