Why aren't lava, lanterns, or ores glowing with Optimum Realism

Optimum Realism uses LabPBR emission (the specular map's alpha channel), not OptiFine's _e files. If glow is missing, turn on LabPBR/emissive support in your shader's Materials tab — and check the "Floodfill" setting if glow only appears at certain times.

Still seeing it?

What does the glow look like?

Emissive support is off in the shader, or it's set to the wrong PBR mode. LabPBR stores emission in the alpha channel of the specular map — the shader has to be told to read it.

  1. Open Shader settings → Materials (or Lighting / Surface) tab
  2. Set PBR / Resource Pack mode to LabPBR (NOT OldPBR, SeusPBR, or Integrated PBR)
  3. Turn Emissive Textures / Emission ON
  4. Press F3 + T in-game to reload — glow appears immediately

That's the shader's "Floodfill" lighting feature interfering. Look for a Floodfill toggle in the shader's lighting settings and turn it OFF — the emission then shows consistently.

Flickering emission was a known bug in old Sodium / Embeddium / Rubidium builds. Update Sodium (and Indium) to current versions, or switch the shader's "requirements"/compatibility option — newer builds fixed it.

Iris + Fabric mod list

OptiFine reads LabPBR emission too, but only on a recent build with shaders active and "Emissive Textures" enabled. Update to the latest OptiFine preview and make sure a LabPBR shader is loaded — plain OptiFine without a shader won't emit.

OptiFine too old?

Related
Why does my Optimum Realism look flat or matte?Why do blocks look flat with shaders on — POM / parallax not working?Which shader works best with Optimum Realism?Optimum Realism is too dark at night or in caves with shaders — how do I brighten it?What mods do I need to run Optimum Realism on Iris + Fabric?

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