Blender Glass BSDF Node Explained

The Glass BSDF node in Blender is a specialized shader designed to simulate refractive and reflective materials like glass, water, crystals, and lenses. It combines Glossy BSDF (reflection) and Refraction BSDF functions into a single node to realistically bend and bounce light through an object. This overview covers the core parameters of the Glass BSDF node, how light algorithms work within it, and how to use it in both Cycles and Eevee render engines.

Core Inputs and Settings

The Glass BSDF node uses three primary settings to control how light interacts with the mesh:

  • Color: Sets the tint of the glass. A pure white color creates clear, transparent glass, while adding a specific color creates tinted materials like colored bottles or stained glass.
  • Roughness: Controls the surface smoothness. A value of 0.0 results in sharp, perfectly clear glass. Increasing the roughness diffuses both the reflection and refraction, creating frosted or brushed glass effects.
  • IOR (Index of Refraction): Dictates the angle at which light bends when passing through the material. Real-world materials have specific IOR values:
    • Air: 1.000
    • Water: 1.333
    • Glass: 1.450 – 1.520
    • Diamond: 2.417

Distribution Algorithms

The dropdown menu on the node changes how microfacet distributions are calculated across the surface:

  • GGX: The default and most versatile distribution algorithm for realistic materials.
  • Multiscatter GGX: Accounts for multiple light bounces between surface microfacets. This prevents rough glass from looking unnaturally dark or losing light energy, making it ideal for frosted glass in Cycles.
  • Beckmann: An older microfacet distribution model, useful for specific vintage rendering styles or metallic glass.
  • Sharp: Removes microfacet calculations entirely, forcing reflections and refractions to remain perfectly sharp regardless of roughness values.

Render Engine Considerations

Cycles

Cycles uses path tracing, allowing the Glass BSDF to function automatically with realistic light bending, reflection, and shadow casting. Because real glass can absorb light rays and cause noise (fireflies), light path limits or caustics settings may need adjustment for complex interior scenes.

Eevee

Because Eevee is a real-time rasterization engine, refraction is not calculated automatically. To make the Glass BSDF work in Eevee:

  1. Go to Render Properties and enable Screen Space Reflections, then check Refraction.
  2. Go to Material Properties for the glass object, navigate to the Settings section, and enable Screen Space Refraction.

Glass BSDF vs. Principled BSDF

While the Glass BSDF node is effective for dedicated glass shaders, Blender's Principled BSDF node can achieve similar glass effects by turning the Transmission weight to 1.0.

Use the Glass BSDF when creating simple, lightweight glass shaders or when combining specific refraction effects using custom node groups. Use the Principled BSDF when the material needs complex surface details, such as surface fingerprints, dust layers, coat layers, or metallic blending on top of the glass.