From BlenderWiki
[edit] PBR Viewport Project
This section gives an overview of the Physicaly Based Rendering/Shading project for Blender's viewport, it's targets and my personal technical choices. Nothing is carved in stone and every idea is welcome.
I will go step by step through the rendering process and discuss each point that are important for PBR.
[edit] Pre Render
1. Update Probes
2. Pre Render Buffers
3. Object Setup
4. Render Surface / Shader compilation
[edit] Bsdf rendering
5. Direct Lighting
6. Indirect Lighting
[edit] Post Render
7. Transparency
8. Post drawing
[edit] Technical details
Minor Features / Improvement Ideas
Planning
Technical Notes