Shader Graph 2026-05-27 Updated

Renderer solution when mask expression by URP stencil buffer is not reflected in Shader Graph

Difficulty Intermediate

Unity Version Unity 2022.3 LTS / Unity 6 対応

Target Audience Shader programmer, technical artist, UI/VFX designer

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Symptom

I tried to implement a "portal effect" or "partial mask" using a stencil buffer in Shader Graph, but even though I set the stencil's Compare Function and Ref Value correctly in the material inspector, the stencil mask did not work and everything was drawn opaquely.

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Root Cause

In URP, direct stencil control on the material side is ignored by default and overridden by the drawing settings specified in Universal Renderer Data, so this is caused by not properly adding and configuring the Renderer Feature "Render Objects".

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Solution

Open the Universal Renderer Data asset and add Render Objects (Renderer Feature). Specify the layer to which the stencil is applied in Filters, enable the Stencil settings, and set the comparison criteria (Ref value, Pass/Fail) defined on the material side.

These are the steps to properly control the "Stencil Buffer" (Stencil Buffer), which is essential when creating 2D/3D cutouts and portals (3D models that can only be seen on the other side of the gate).

Specific solution

1. Setting up Universal Renderer Data

Open the Universal Renderer Data asset you are currently using.

2. Add Render Objects Feature

Select Add Renderer Feature ➔ Render Objects at the bottom to add it.

3. Synchronize the stencil mask

Expand the added Feature, select the layer to which the object you want to mask belongs in Filters ➔ Layer Mask, enable the **`Stencil`** checkbox at the bottom, and set the following parameters.

Value: An integer that matches the material side (e.g. `1`)
Compare Function: `Equal` (or mask target setting)
Pass: `Keep`

Explanatory diagram of the stencil buffer mask and portal drawing mechanism using URP's Render Objects

Figure 1: Mechanism for permitting and discarding drawing by stencil comparison processing (comparison and judgment of Ref value and buffer value)