The creators of Portal 2: Community Edition presented a new mini-developer diary. They talked about improving the lighting engine:
“In the new renderer, all light objects in the engine can be drawn dynamically and cast real shadows while preserving the precompiled bounce lighting from the original renderer.”
At the following link, a promo page is available where you can explore a slice of the game in your browser.
Video: https://youtu.be/5ovDgRtosGA
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Cover art author: Valve. Image source: YouTube.com