If your resource pack relies on specular maps, normal maps, or emissive textures designed for SEUS (like realistic stone bricks that get wet in the rain), The blocks will look flat. Vanilla PBR support is getting there, but advanced PTGI-specific PBR is lagging.
Using Iris is recommended over OptiFine for SEUS PTGI because (built into Iris) provides the CPU overhead needed to handle path tracing at playable frame rates. 1. Install the Iris Mod How To Install Iris Shaders Minecraft (Quick Guide 2026)
It is important to clarify the tech here. Unlike , which uses dedicated RT cores on the GPU for hardware ray tracing, SEUS PTGI calculates path tracing via software compute shaders.
SEUS PTGI on Iris is the ultimate showcase of what Minecraft Java Edition can look like. It transforms the game from a blocky sandbox into a near-photorealistic architectural simulator.
Running this shader through the mod (a modern, high-performance shader loader) is currently one of the best ways to experience next-gen graphics in Java Edition. Here is the breakdown.
For a long time, loading SEUS PTGI on Iris resulted in a black screen, missing shadows, or the dreaded "Rendering setup has failed" error.
However, the Iris team has been working hard on a feature called