MINECRAFTHUB.IO
Shaders

Rethinking Voxels

Rethinking Voxels is a beta Iris shader for Minecraft Java that replaces standard lighting with voxel-based colored blocklight, global illumination, and sharp shadows.

By gri573 via Modrinth.

Rethinking Voxels shader casting sharp block shadows across a Minecraft scene
Section
Shader
Platform
Java
Versions
v 1.20.1 / 1.20.4 / 1.21.1 / 1.21.2 / 1.21.3 / 1.21.4 / 1.21.5 / 1.21.6 / 1.21.7 / 1.21.8 / 1.21.9 / 1.21.10
Last checked
Updated
Global illumination in Rethinking Voxels with light bouncing between block surfaces
Global illumination in Rethinking Voxels with light bouncing between block surfaces
Modern interior room lit by stained glass tinting nearby blocks in Rethinking Voxels
Modern interior room lit by stained glass tinting nearby blocks in Rethinking Voxels
Revamped skylight using global illumination for natural shadow depth in Rethinking Voxels
Revamped skylight using global illumination for natural shadow depth in Rethinking Voxels
Entity shadows cast by all light sources including blocklight in Rethinking Voxels
Entity shadows cast by all light sources including blocklight in Rethinking Voxels
Cave interior lit by global illumination in Rethinking Voxels
Cave interior lit by global illumination in Rethinking Voxels
Specular highlights from colored blocklight on smooth block surfaces in Rethinking Voxels
Specular highlights from colored blocklight on smooth block surfaces in Rethinking Voxels
Volumetric lighting with blocklight scattering through the air in Rethinking Voxels
Volumetric lighting with blocklight scattering through the air in Rethinking Voxels

Rethinking Voxels is a Java Edition shader for Iris that replaces Minecraft's standard lighting with a voxel-based colored blocklight system. Every light source, including torches, lanterns, and stained glass, emits colored rays that scatter in the air, tint nearby surfaces, and cast sharp, defined shadows. The shader is built on Complementary Reimagined and runs on 1.20.1 through 1.21.x.

Effects and Lighting

The core technique is voxel-based light propagation: the shader samples world geometry at a voxel level to determine where light travels, rather than relying on Minecraft's flood-fill approximation. This enables several effects that standard shading cannot produce.

  • Global illumination: light bounces off surfaces multiple times, filling areas with indirect color.
  • Colored blocklight: torches, lanterns, stained glass, and other sources each cast their own color.
  • Sharp block shadows: hard-edged shadows from all light sources, including sun, moon, and blocklight.
  • Entity shadows: mobs and players cast shadows from every light source, not only the sun.
  • Volumetric lighting: blocklight scatters visibly through the air in dim spaces and caves.
  • Specular highlights: smooth surfaces pick up colored reflections from nearby light sources.

How to Install Rethinking Voxels

Rethinking Voxels requires Iris Shaders. OptiFine is listed as a supported loader on the project page, but Iris is the primary and recommended pipeline.

  1. 1.Install Iris Shaders for your Minecraft version. Iris can be installed standalone or included in a Fabric modpack.
  2. 2.Download the Rethinking Voxels ZIP file from the Modrinth project page.
  3. 3.Open Minecraft and go to Options, then Video Settings, then Shader Packs.
  4. 4.Click Open Shader Pack Folder and move the downloaded ZIP into that folder.
  5. 5.Select Rethinking Voxels from the shader list and click Apply.

Performance and Settings

Global illumination and voxel-based lighting carry a significant GPU cost compared to simpler shader packs. Systems that run mid-range shaders at comfortable frame rates may see a noticeable reduction with Rethinking Voxels at full settings. The Iris shader settings menu exposes options for adjusting GI quality and shadow resolution, which can help on less powerful hardware.

Compatibility

  • Loader: Iris (primary). OptiFine is listed on the Modrinth project page.
  • Minecraft Java versions: 1.20.1, 1.20.4, 1.21.1 through 1.21.x.
  • Client-side only. The shader does not affect server behavior.
  • Bedrock Edition is not supported.

Questions about this entry.

  • How do I install Rethinking Voxels?

    Install Iris Shaders for your Minecraft version, then download the Rethinking Voxels ZIP from Modrinth. Open Minecraft, go to Options, Video Settings, Shader Packs, and click Open Shader Pack Folder. Drop the ZIP in, then select it from the list and click Apply.

  • Does Rethinking Voxels work with OptiFine?

    OptiFine is listed as a supported loader on the Modrinth project page. Iris is the primary and recommended loader. If you use OptiFine, check the project page for any version-specific notes before downloading.

  • Which Minecraft version does Rethinking Voxels support?

    Rethinking Voxels supports Minecraft Java Edition 1.20.1, 1.20.4, and 1.21.1 through 1.21.x. Check the Modrinth project page for the latest supported version list, as new minor versions are added regularly.

  • Is Rethinking Voxels good for low-end PCs?

    No. Global illumination and voxel-based lighting are computationally demanding. Rethinking Voxels is aimed at systems with capable GPUs. If frame rate is a concern, a lighter shader pack is likely more appropriate.

  • Can I use Rethinking Voxels on multiplayer servers?

    Yes. Rethinking Voxels is a client-side shader and does not affect server behavior. You can use it on any server that permits client mods, including public servers and Realms.