Photon Engine Shaders

A hybrid voxel ray-traced shaderpack for Minecraft Java 1.20.1 (Iris / Oculus). Lighting, reflections and atmosphere are computed from an actual voxel copy of the world around you, not just from what is on screen.

Lighting

• Voxel global illumination:
  • screen-space and voxel ray tracing with 1–2 bounces;
  • a world-space radiance cache that adds further light bounces over time;
  • coloured light bleeding.
• Many-light direct lighting (ReSTIR): every torch, lamp and lava block casts real voxel shadows.
• Soft shadows:
  • PCSS with a penumbra from the sun’s real size;
  • coloured shadows through stained glass;
  • light diffusing through leaf canopies;
  • contact shadows.
• Leak guards: sealed caves stay dark.

Reflections & water

• Reflections: SSR backed by voxel ray tracing, so reflections of geometry outside the screen don’t vanish. Roughness-aware.
• Water:
  • multi-scale waves, refraction and real Fresnel;
  • depth-based absorption and caustics computed from the waves themselves;
  • Snell’s window underwater;
  • shoreline foam.

Sky & weather

• Physically based atmosphere: Rayleigh/Mie multiple scattering and aerial perspective.
• Simulated weather drives multi-layer volumetric clouds (cumulus, alto, cirrus) that cast shadows on the terrain.
• Volumetric light shafts, fog, rain wetness with puddles, simulated campfire smoke.

Materials

• LabPBR 1.3: normal and height maps, roughness, metals (true complex IOR), porosity, subsurface scattering, emission.
• POM with self-shadowing.
• Sensible fallback materials without a PBR pack.

Styles

• Bedrock RTX Look: glassy water with the vanilla water texture, thick god rays (also through windows), dim interiors, glossy blocks and filmic colours.
• Anime / Cel Shading: banded light, tinted shadows, ink outlines, flat colours, two-tone clouds.

PhotonFrameGen support

Works with the PhotonFrameGen frame generation mod. The pack hands it the first-person hand mask and per-pixel depth, so generated frames reproject walls exactly and keep the hand undistorted.

Requirements

macOS is not supported (no OpenGL 4.3).

Presets

Low (Performance), Medium, High (Balanced, default), Ultra (RTX Ultra), Cinematic.

Known limitations (beta)

• This is software voxel ray tracing, not hardware RTX.
• It is demanding: start with the High or Medium preset.
• Distant Horizons is not supported yet.
• Entities are not in the voxel world, so they only appear in screen-space reflections.
• In-game testing is still limited. Please report issues with your GPU and driver, a screenshot, and latest.log.