ShaderSample sample overview

Updated: May 7, 2026

Overview

This sample demonstrates how to apply custom GPU shader effects to the passthrough camera feed by using the GPU texture provided by the Passthrough Camera API as input to a fragment shader. It implements a water surface effect that vertically mirrors the camera feed, distorts it with animated waves, and blends it with caustic textures and color tinting. This is useful for developers who want to apply real-time post-processing or visual effects to the camera feed rather than simply displaying or analyzing it.

View the sample source code on GitHub⁠.

What you will learn

Retrieve the GPU texture from the Passthrough Camera API for use in custom shaders

Implement a traditional CG vertex/fragment shader that processes the passthrough camera texture

Use normal maps and time-based UV distortion to create animated visual effects

Properly handle stereo rendering for Quest headsets in custom shaders

Blend multiple textures (camera feed, normal map, detail map) to create composite effects

Requirements

Quest 3 or Quest 3S headset

Unity development environment configured for Quest

Physical headset or Meta Horizon Link v2.1+ (XR Simulator is not supported)

For Unity versions, SDK dependencies, and complete build prerequisites, see the sample README. For development environment setup, see the Passthrough Camera API Getting Started Guide.

Get started

Clone or download the Unity-PassthroughCameraApiSamples repository⁠ from GitHub. Open the project in Unity, navigate to Assets/PassthroughCameraApiSamples/ShaderSample/, and open the ShaderSample.unity scene. Build and deploy to your Quest 3/3S device using the instructions in the README. When you run the sample, grant camera access permission when prompted, and you see a water surface effect applied to the passthrough camera feed.

Explore the sample

The sample consists of a scene with a water plane, a custom shader, and a manager script that connects the passthrough camera texture to the shader.

File / Scene	What it demonstrates	Key concepts
ShaderSample.unity	Complete scene setup with camera rig, passthrough configuration, and water surface	Scene composition, passthrough building blocks, spatial placement
Scripts/ShaderSampleManager.cs	Runtime connection between camera feed and shader material	Coroutine-based initialization, texture assignment, permission polling
Shaders/ShaderSampleWater.shader	Custom CG shader implementing water reflection effect	UV distortion, time-based animation, vertical mirroring, stereo rendering
Materials/ShaderSampleWaterMat.mat	Pre-configured material with shader parameters	Material property tuning, texture slots
Prefabs/ShaderSampleManagerPrefab.prefab	UI prefab with manager script and debug text	World-space canvas, component wiring
PassthroughCamera/Scripts/RequestPermissionsOnce.cs	Shared script for automatic permission requests	Runtime initialization, permission flow
PassthroughCamera/Prefabs/PassthroughCameraAccessPrefab.prefab	Shared prefab containing the PassthroughCameraAccess component	`MRUK` integration, camera configuration (left camera, 1280x960)

Runtime behavior

When you run the sample on Quest 3/3S, a permission dialog appears requesting headset camera access. Once you grant permission, the debug text changes from “No permission granted.” to “Permission granted.” The passthrough camera feed starts streaming, and you see the real environment around you with a flat water surface plane positioned 4 meters below you. Four cube borders form a pool shape around the plane. On the plane surface, the live passthrough camera feed renders as a vertical mirror reflection. The effect includes animated wave distortion, cyan color tinting, caustic texture overlay, and increased brightness — simulating looking down at a reflective water surface.

Key concepts

Retrieving the GPU texture

Notice how the sample obtains the GPU texture from the PassthroughCameraAccess component (provided by MRUK) and assigns it to the material in ShaderSampleManager.cs:

m_renderer.material.SetTexture("_MainTex", m_cameraAccess.GetTexture());

The script waits for m_cameraAccess.IsPlaying to return true, then assigns the texture once. The GPU texture handle updates its content each frame automatically without additional SetTexture calls. See Passthrough Camera API documentation for details on PassthroughCameraAccess.

UV distortion with normal maps

The fragment shader in ShaderSampleWater.shader samples a normal map texture with UV coordinates animated by _SinTime.y, then uses the normal map’s XY channels to offset the camera texture UVs — creating a scrolling wave distortion effect. This pattern decouples the distortion animation from the camera feed, allowing the waves to move independently of the reflected image.

Vertical mirroring for reflection

After distorting the UVs, the shader inverts the vertical coordinate (distortedUV.y = 1 - distortedUV.y) to flip the camera image upside down, simulating a reflection on a water surface. This simple transformation combined with the wave distortion creates a convincing reflection effect without requiring ray tracing or environment probes.

Stereo rendering support

The shader includes Unity’s stereo rendering macros (UNITY_SETUP_INSTANCE_ID, UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO, UNITY_VERTEX_OUTPUT_STEREO, UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX) to ensure the camera texture renders correctly for both left and right eye views on Quest headsets. This is essential for custom shaders processing passthrough camera content. See ShaderSampleWater.shader for the complete stereo implementation.

Extend the sample

Modify the shader parameters (_WaveAmplitude, _NormalOffsetX, _NormalOffsetY, _ReflectIntensity) in the material to experiment with different water effects — try faster waves, stronger distortion, or different color tints

Replace the water normal map and detail textures with other textures to create different visual effects (frosted glass, heat distortion, kaleidoscope patterns)

Combine techniques from the CameraToWorld sample to align the shader effect with specific real-world surfaces using camera intrinsics and extrinsics

Passthrough Camera API Overview⁠

Passthrough Camera API Getting Started Guide⁠

Mixed Reality Utility Kit (MRUK) Documentation⁠

Unity-PassthroughCameraApiSamples GitHub Repository⁠

CameraViewer sample — simplest passthrough camera display⁠

CameraToWorld sample — world-space alignment with camera intrinsics⁠