Blenderビューポート上でリアルタイムPBR（Physically based rendering）を可能にした独自ビルドバージョン！「Blender PBR viewport Branch v0.4」が公開されております。
※2016/06/07 – “アドオン”という記載をしておりましたが、正しくは”独自ビルドを行った別バージョン”との事でした。記事全体を修正してます。ご指摘いただいた方々、ありがとうございました。

Blender PBR viewport Branch v0.4

PBR viewport Branch V0.4 – 06/06/2016

• Oren-nayar Diffuse (Env lighting)
• Velvet Shader (Env lighting + Point lights)
• Toon Shader (Env lighting + Point lights)
• Ashikhmin & Beckmann distributions for isotropic and anisotropic
• Closest Filtering for Texture node
• Material layer overide but only for material. So you can preview one material on every
• objects without assigning it to each object.
• Linearly Transformed Cosines to shade Area lights with the Glossy GGX (other
• distributions use the same LUT)
• Material AO to apply occlusion during the shading stage an not at the post process stage.
• Algorithm is slow but correct (matches cycles)
• Screen Space Reflections for Sharp Glossy shader. Algorithm is from Morgan McGuire
• blog and the step is always 1px so reflections can’t go far.
• Backface buffer to improve screen space effects.
• Bias parameter to control the accuracy of the Environment Sampling.
• Performance : Use a jitter texture + a sample texture to generate sampling random vectors instead of computing everything inside the shader. (this takes 2 texture slots though)
• Performance : Lights shadowing (and lamp nodetree) are evaluated only once per Material.
• Codebase Change : major thing I did is not using the common uniform interface for passing uniforms related to the sampling and PBR. I also splited the glsl files into more managable ones.

cycles renderとの比較も遜色無い感じですね。
旧バージョンのプレビュー＆解説動画も貼り付けておきます。

Blender PBR viewport Branch v0.35

Blender PBR viewport Branch v0.2

関連リンク

• GLSL PBR Shader for viewport
• Clément FOUCAULT Portfolio