Question Trying to get DOTS occlusion working, sample won't work as described

Hi!

I'm trying to run the hybrid occlusion in unity 2020 LTS but the occlusion doesn't work, the documentation says it should occlude something but mine shows 0 occluded:



Does someone know why it's not working as described?

It's this sample: https://github.com/Unity-Technologi...PSamples/Assets/SampleScenes/OcclusionCulling

 

mentioned on discord but you might miss that
I loaded it up and it seemed to work fine


Unity: 2020.3.30f1
Entities: 0.50.0-p24
Hybrid Renderer: 0.50.0-p24
HDRP: 10.8.1

I did not try URP

 

Thanks, opening the scene in a new project worked for both URP and HDRP.

Now the issue is getting occlusion to work in my own scenes, and I'm getting out of range exception errors when I put more than 1529 mesh objects in my scene (subscene or not, same problem) :

IndexOutOfRangeException: Index -82 is out of range of '33' Length.

Unity.Collections.NativeArray`1[T].FailOutOfRangeError (System.Int32 index) (at <3be1a7ff939c43f181c0a10b5a0189ac>:0)

Unity.Collections.NativeArray`1[T].CheckElementReadAccess (System.Int32 index) (at <3be1a7ff939c43f181c0a10b5a0189ac>:0)

Unity.Collections.NativeArray`1[T].get_Item (System.Int32 index) (at <3be1a7ff939c43f181c0a10b5a0189ac>:0)

Unity.Rendering.Occlusion.MOCTestJob.Execute (Unity.Entities.ArchetypeChunk chunk, System.Int32 chunkIndex, System.Int32 firstEntityIndex) (at Library/PackageCache/com.unity.rendering.hybrid@0.50.0-preview.24/Unity.Rendering.Hybrid/Occlusion/BurstIntrinsics/MOCTestJob.cs:83)

Unity.Entities.JobChunkExtensions+JobChunkProducer`1[T].ExecuteInternal (Unity.Entities.JobChunkExtensions+JobChunkWrapper`1[T]& jobWrapper, System.IntPtr bufferRangePatchData, Unity.Jobs.LowLevel.Unsafe.JobRanges& ranges, System.Int32 jobIndex) (at Library/PackageCache/com.unity.entities@0.50.0-preview.24/Unity.Entities/IJobChunk.cs:401)

Unity.Entities.JobChunkExtensions+JobChunkProducer`1[T].Execute (Unity.Entities.JobChunkExtensions+JobChunkWrapper`1[T]& jobWrapper, System.IntPtr additionalPtr, System.IntPtr bufferRangePatchData, Unity.Jobs.LowLevel.Unsafe.JobRanges& ranges, System.Int32 jobIndex) (at Library/PackageCache/com.unity.entities@0.50.0-preview.24/Unity.Entities/IJobChunk.cs:368)

 

Thanks for pointing out this culling demo! Didn't know that existed. I have a test scene that could greatly benefit from occlusion culling since the goal was to test how much can be saved by culling:
https://forum.unity.com/threads/why...hen-using-monobehaviour.1250830/#post-8022620

I'm going to try and make it work in my test. I'll report back with my results.

 

If anyone is interested, I debugged the the above error.

HybridV2Culling can give StartIndex a negative value



Fix

HybridV2Culling - line 419 remove the cast to short
HybridV2RenderSystem - line 827 change StartIndex to int

I do not know if there will be consequences I haven't tested it enough to be certain but it seems to work. (At the very least this struct should be reordered for memory)

250k cubes


Performance is great

 

That borg cube!

 

So, I got culling enabled in my voxel test scenes and played around with it. Given a hollow cube with quad meshes on all 6 sides it doesn't actually occlude that much even though it could exclude at least all of the backsides. Perhaps the algorithm is very conservative, or was simply seeing through my meshes which are essentially a front and a back quad some distance apart - maybe the system was "seeing through the gaps" despite the meshes perfectly aligning visually.

I also made a test with an occluder wall, hiding the entire cube. It did occlude it entirely, but nevertheless I see a significant drop in framerate due to the number of occlusion tests alone. It simply doesn't matter if a couple more or less meshes are rendered.

I conclude that for occlusion to make sense you have to be able to occlude rather complex meshes, as opposed to my tests where I have thousands of extremely simple meshes, each of which also acts as occluder too.

Also, for a voxel world it's fairly trivial to write your own occlusion system that does far fewer computations due to the numerous assumptions you can make about the world and the sizes and orientation of meshes and so on.

 

Will support android arm in 0.50.1?

 

Tertle, you are a godsend. You know everything about everything. The patch works great for now. Thank you