VR Rendering with Unity 6.0+

(WORK IN PROGRESS…)

I am a perception-driven rendering researcher (2026). VR opened the endless opportunity to explore and exploit the human perceptual limitations to simulate life-like visualization. However, the evaluation process of a perception-driven rendering often requires rigorous user study. The lack of standard and well accepted perceptual quality metrics (as for now, 2026) makes the evaluation process even more complicated. The user study process for perception-driven research is often designed from the scratch, which is time and cost consuming. Therefore, the focus of this tutorial will be more user study design with Unity game engine. I have used the HTC Vive Pro Eye for tutorial. If you need some basic knowledge regarding eye tracking, e.g., SRanipal plugin and runtime, you can follow this old tutorial; however, using the OpenXR is highly recommended as the OpenVR has already been depricated.

Prerequisites

1. SteamVR runtime
2. Sranipal runtime
3. Vive-SRanipal-Unity-Plugin.unitypackage, I used version 1.3.6.8. To the best of my knowledge, that is the last updated version (2026). In the SRanipal SDK folder, you will have C, Unreal, and Unity implementations. Drag and drop the package will be visible as ViveSR folder in the project. Any other slightly older version also might work (untested) similarly. For eye tracking, the SRanipal Eye Framework under ViveSR/Prefabs is required. Alternatively, OpenXR might also work for eye tracking (e.g., XR_EXT_eye_gaze_interaction).

Unity and The Rendering Pipelines

For a beginner, it might be confusing to get familiar with different rendering pipelines mentioned in the Unity (at least it was confusing to me) and select the suitable pipeline for the VR. To my understanding, the Unity’s rendering pipelines are classified as below:

1. Scriptable Rendering Pipeline (SRP)
   1. Universal Rendering Pipeline (URP), that includes Forward, Forward+, Deferred (tile-based deferred rendering?), and Deferred+ Reference pipelines
   2. High Definition Render Pipeline (HDRP)
   3. Lightweight Render Pipeline (LWRP)? where does it fit?
   4. Custom Render Pipeline (CRP) Ref
2. Built-In Render Pipeline (lagacy version, not recommended)

The URP and HDRP can’t be used simultaneously, as both are built with SRP, and their render paths and light models differ. As per the Unity 6+ announcement (2025), URP and HDRP will be the default Render Pipelines, but the Built-In Render Pipeline (which is the default for now) will be supported at least 2 years after the release of Unity 6.