Matte Shader (Only Shadows) in HDRP

Hi everyone,

I'm using HDRP for my current project and I need to cast a shadow on a transparent plane. So far I found quite a bunch of tutorials on how to do that using regular Unity shaders in SRP, but none for HDRP (preferably using default shaders or Shader Graph).

Thanks for your help!

 

I think semi-transparent shadows are for Realtime Raytracing only. That's the only way I know that works in Unity out of the box.

 

@Bordeaux_Fox what do you mean exactly? Like you can make a Shadow Matte shader (transparent shader that receives only shadow info) for RTX shadows in HDRP? How would you go about doing that?
I realized last night that Unity has an option for making a shadow matte in the Unlit shader graph, but when I played around with it it had fairly bad results with RTX shadows. Have you had success making an RTX shadow matte shader?

 

According to the newest update on HDRP, you're able to get semi-transparent shadows without realtime raytracing:

Changelog for HDRP 7.2.0

• Added semi-transparent shadows for point and spot lights.
• Added support for semi-transparent shadow for unlit shader and unlit shader graph.

For realtime raytracing shadows see here: https://docs.unity3d.com/Packages/c...definition@7.2/manual/Ray-Traced-Shadows.html

 

Hi. In Blender EEVEE is use this method because on the ground there is mostly reflection involved.

Is there an easy to do this in a SG as extension of the method described before?
It s a little limitating to have the Shadow Matte only in the Unlit Master.

 

@Remy_Unity
I have tried to copy your shader but with no luck, for me there are no shadows appearing

See the screen shots below for extra information:

Here is my shader graph (copy of what you did):


Here is my material:


This is the material applied to the mesh (probably redundant):


And here is the result, no shadow sadly..


How can i get this to work?

Side question also my properties are not showing up in the inspector.

Extra information:

Using unity version 2019.3.3f1
Using HDRP version 7.1.8

If more information is required pls let me know so i can add it

 

Hi sadly I cant share my project..
But could you give me some pointers on where to look? Maybe player settings?
Or could i just share the shader, or some other specific file?

 

If you could isolate the issue in a specific scene with non protected assets, like the susane head and an open source HDRI, that would be great, to share it safely.
If you can't, there is maybe the option to PM me the project.

 

Thanks for the tip. See the files below:
(If any other file is required let me know so i can also share those)

 

Yeah you'r right that made the floor appear. But In gray without transparancy or shadows. How do i make sure it is transparent with shadows?

EDIT @Remy_Unity Did you see shadows and transparency?

 

Awesome, it turned out the light was not emitting shadows... Thank you

 

cheers this helped me out

 

Remy, can this be done in the latest version of shader graph? I don't see the shadow matte option anywhere. @Remy_Unity

 

In the Shader Graph Editor, in the Graph Inspector on the right, go to the Graph Settings tab. Shadow Matte is all the way down at the bottom

 

Is there a way to have both matte shadow and ambient occlusion at the same time ?

We would like to set characters on a live action environnement and we would like contacts with the floor. We currently use a proxy to cast shadow on it in the matte shadow way which works great. Now we would like to also have the contact shadows with the proxy and that's what the ambient occlusion would do. If I put an opaque plane the ambient occlusion works great but now I would like to make it with the matte shadow added. Maybe with a custom pass or the compositor?

 

Can you push done project to here?

 

I am not able to import package from #12 into Unity 2021.2.18f1, Silicon - package is grayed out and it cannot be selected. What i am missing? :\