No depth information in "After Depth and Normal" custom pass injection point

Hey everyone,

I started working with the custom pass feature in HDRP and ran into a slight issue. I am trying to draw occluded opaque geometry with a specific color (pretty basic effect in lots of games), so I set up a custom pass that does exactly that and chose the "After Depth and Normal" injection point.



It appears as if there's no depth information available at this point though (ZTest Greater doesn't work) which is kind of strange, isn't the whole idea of this point to have the depth information available?

As a workaround I can choose the "Before Transparent" injection point where the depth information appears to be present, but I would have to render the object as a transparent object to make sure it gets rendered after the occlusion highlight to fix having a highlight due to self occlusion (which is obviously not ideal).



Am I missing something here or is it a bug?
Do I have to manually write to DEPTH in the enviromental shaders?
Do I have to sample the depth texture instead of relying on ZTest?

Thanks for the help, I really appreciate it!

- Alex

 

Thanks for the quick reply! I tried replicating your setup and while it's basically working I still have the issue that I get highlights on the object due to it's own occlusion. What would be the best solution to handle this issue in HDRP?



I think you might have to same issue in your demo but can't see it due to backface culling and the object thus not having multiple surfaces on top of each other.

 

I prepared a clean new HDRP project with the same setup for you so you can take a look. In addition to the self occlusion I am also getting this weird tiling issue which looks as if the depth texture resolution is much lower than the viewport resolution, not sure what's going on there.



Using Unity 2019.3.2f1, HDRP version 7.18

You can download the project here: https://drive.google.com/open?id=1nZW90HXUL0HysZuZ1DWNFIes0Ql6mVMK

If you need additional information let me know!

 

I might be wrong here but isn't it just an issue with the way HDRP is designed instead of a bug or setup issue?

Isn't the custom pass at the "After Depth and Normal" stage expected to also highlight areas that are hidden behind the object itself (like e.g. the right ear behind the left ear)?

The depth for the scene at the "After Depth and Normal" stage should look something like this:



Therefore faces of the object that are occluded by the object itself and face the camera are highlighted in the custom pass.

In order to fix this I'd need to render the depth of the whole scene, then render the highlight, and afterwards render the depth of the highlighted object and continue rendering as usual. Is there a way to set something like this up in HDRP other than rendering the highlighted object as transparent?

 

Thank you very much for your help! I was hoping to avoid rendering the model with a transparent material due to Overdraw, but I think this might not be possible in the current HDRP.



Going forward I might have to look into writing a custom pipeline to have more control over the setup