In the world of Minecraft modding, three letters strike fear and excitement into the heart of every graphics enthusiast: PTGI (Path Traced Global Illumination). Specifically, Sonic Ether’s Unbelievable Shaders (SEUS) PTGI is the gold standard for realistic lighting.
However, a war has been raging in the modding community between two rendering APIs: Iris (for Fabric) and Oculus (the Forge port of Iris). Players constantly ask: Can I use SEUS PTGI on Forge with Oculus? Or do I need Iris? And what does "Top" mean?
Here is the hard truth about the current compatibility landscape.
Goal: Play Forge modpacks in VR with path tracing.
Have a different combination that works better for you? Let us know in the comments below.
SEUS PTGI (Path Traced Global Illumination) is generally compatible with Iris and its Forge-equivalent Oculus, but users often experience specific graphical bugs that vary by version. Core Compatibility Overview
Mod Loaders: Iris is built for Fabric and NeoForge (1.21.1+). For standard Forge, you must use Oculus, which is a port of Iris designed specifically for that loader. SEUS PTGI Versions: seus ptgi iris compatibility oculus forge top
HRR 2.1: Widely considered stable and compatible with modern versions of Iris/Oculus.
HRR 3: Known to have major issues on older Iris versions (like blurry entities or broken shadows), though newer Iris versions (1.6.17+) have improved support.
E12: Generally works, but may lack some specific features intended for OptiFine. Known Technical Issues
Motion Blur: Often appears "broken" or creates unplayable blurring because SEUS uses a function (at_velocity) that was designed for OptiFine and does not always translate correctly to Iris/Oculus.
Entity Visuals: Mobs, item frames, and paintings may appear blurry, flicker, or have graphical glitches.
Flywheel Conflict: If using the Create mod, you often need the Iris & Oculus Flywheel Compat mod to prevent rendering issues with moving parts when shaders are active. Setup Recommendations In the world of Minecraft modding, three letters
To achieve the "top" experience with SEUS PTGI on these platforms:
SEUS PTGI HRR 3 , full compatibility with (Fabric) and (Forge) is now widely available, though it requires specific versions of these mods to avoid common graphical glitches. Core Compatibility Status SEUS PTGI HRR 3
: Generally works on recent versions of Iris (1.6.x+) and Oculus. Older versions of Iris (e.g., 1.2.1) had significant regressions causing PTGI 3 to fail, often appearing as "default Minecraft". SEUS PTGI HRR 2.1 & E12 : Highly stable on both Iris and Oculus. Forge Support
is a direct fork of Iris for Forge, any shader verified for Iris will typically work on Oculus provided you use a matching performance mod like Essential Configuration Tips
To achieve "top" performance and visual fidelity with this setup: Disable Motion Blur : A specific SEUS function ( at_velocity
) is built for OptiFine and can cause "unplayable" breaking in Iris/Oculus if motion blur is active. Entity Performance : For Forge users, installing the Iris & Oculus Flywheel Compat Have a different combination that works better for you
mod is critical. It fixes a performance drop where shaders would normally disable efficient entity rendering (GPU Instancing) used by mods like Known Conflicts : As of late 2024, Distant Horizons
remains largely incompatible with SEUS PTGI, often causing complete lighting failures or crashes. Performance Comparison
The short answer is Yes, but only under specific conditions.
Let’s build the compatibility table:
| Component | Required Version | Compatible with SEUS PTGI? | Notes | | :--- | :--- | :--- | :--- | | OptiFine | Any | ❌ No | OptiFine cannot run PTGI HRR 3.0+ due to rendering conflicts. | | Sodium (Fabric) | 0.4.10+ | ❌ No (needs Iris) | Sodium is a backend; it doesn't render shaders. | | Iris (Fabric) | 1.6.x+ | ✅ Yes (Native) | Best performance. Use "SEUS PTGI HRR Test" or "HRR 3." | | Oculus (Forge) | 1.6.x+ (ported) | ✅ Yes (Experimental) | Works for SEUS PTGI HRR 2.1 and 3.0, but shadows may glitch. | | Rubidium (Forge) | 0.6.0+ | ❌ No | Requires Oculus as an add-on. |