Stencil Operations

Unity Engine
, ,
1

I want to perform stencil operations on the depth buffer to occlude specific object pixels.
I am able to do this with the scriptable render pipeline (LWRP) and URP.

Is this possible to achieve in the HDRP? How so? Are Stencil operations possible with Shader Graph?

2

Hello (Joey?),
I asked a similar question and though many have taken a look at it, no one has replied.
However, as of HDRP’s latest update, custom passes are enabled

https://github.com/alelievr/HDRP-Custom-Passes

I wondered if a custom pass would have the features needed for a stencil or depth pass shader, but without further comment from either Unity or someone who has done extensive experimentation - it is difficult to know.

3

i need it for urp
how you do it?

4

Hi, we currently don’t expose stencil control in HDRP, this is a work plan for future version

HDRP have only two user bit:
https://github.com/Unity-Technologies/Graphics/blob/master/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/HDStencilUsage.cs

[GenerateHLSL]
internal enum StencilUsage
{
Clear = 0,
// Note: first bit is free and can still be used by both phases.
// — Following bits are used before transparent rendering —
RequiresDeferredLighting = (1 << 1),
SubsurfaceScattering = (1 << 2), // SSS, Split Lighting
TraceReflectionRay = (1 << 3), // SSR or RTR
Decals = (1 << 4), // Use to tag when an Opaque Decal is render into DBuffer
ObjectMotionVector = (1 << 5), // Animated object (for motion blur, SSR, SSAO, TAA)
// — Stencil is cleared after opaque rendering has finished —
// — Following bits are used exclusively for what happens after opaque —
ExcludeFromTAA = (1 << 1), // Disable Temporal Antialiasing for certain objects
DistortionVectors = (1 << 2), // Distortion pass - reset after distortion pass, shared with SMAA
SMAA = (1 << 2), // Subpixel Morphological Antialiasing
AfterOpaqueReservedBits = 0x38, // Reserved for future usage

// — Following are user bits, we don’t touch them inside HDRP and is up to the user to handle them —
UserBit0 = (1 << 6),
UserBit1 = (1 << 7),
HDRPReservedBits = 255 & ~(UserBit0 | UserBit1),
}

This can be used when you are writing custom postprocess / custom pass manually.

5

You have an example of a custom pass that uses the stencil to select which part of the objects are affected by the see-through effect: https://github.com/alelievr/HDRP-Custom-Passes/blob/master/Assets/CustomPasses/SeeThrough/SeeThrough.cs

6369774--708996--87780070-37e49700-c82e-11ea-9d03-d5ce2a4410c6.gif

As @SebLagarde said, there will be a future version where you’ll be able to control stencil stuff in the custom pass UI but right now it’s only possible in a script.

6

So I took in hand this package and so far it looks very promising.

I wonder it this would be doable this way to “cut” a hole inside an object. Like instead of having the stencil appearing before everything, making it an invisible plane and disabling the render of every objects with a certain layer behind it, in order to have certain part of objects disappearing ?

Would that be possible to guide me on a way to achieve this using this package ?

EDIT :
I managed to find a way using also the custom pass : rendering - Is it possible to create a DepthMask effect in Unity's HDRP? - Stack Overflow