Terrain rendering issue on iOS, please help

Hi all,

So I am looking at a very strange Terrain rendering issue that only appear on iOS Metal (not on macOS Metal, not on Android Vulkan, not on Windows DirectX), it looks like this if we strip the scene down to its terrain:



I am completely bewildered by why there are random holes in the terrain mesh; we are using the built-in pipeline with default unity terrain shader, this issue only appears on iOS.

Any clue on what on earth might be happening here? The holes even flicker for some reasons, as if some vertices are getting offset by something constantly.

 

To add, this only happens if I enable "Draw Instanced" on terrain for iOS.

 

The more I look at this Draw Instanced issue the more it feels like a bug, so I submitted one: case 1230409, if anyone from Unity can take a look at my sample, I would be grateful!

 

I'm encountering the same issue with Terrain when enabling Draw Instanced on IOS...first with 2019.1 and I've verified the issue persists in 2019.2.7. Which version of Unity are you on? I'm not seeing the issue in Android/OpenGL, just IOS/Metal.

For now we're keeping it disabled.

 

For people looking at this thread: this issue being handled by Apple and Unity, but you can easily workaround it.

https://forum.unity.com/threads/terrain-instancing-anisotropic-textures-glitches.795267/