How Cube Map Reflections work?

[Od1sseas]

In GTA 5 (First mission), when i see on the ground i still see reflections (They are not static and Screen Space Reflections wouldn't work because i was looking on the ground). I thought this was possible only using Ray Tracing.

[tikker]

Ray tracing is indeed what enables you to also calculate/show reflections of stuff that is off screen. The answer is in your question though: cubemaps. You just roughly approximate what will be reflected. If you study your puddles in detail you'll likely see it's not a totally correct reflection. Here's an explanation specific to GTA V actually:

 

http://www.adriancourreges.com/blog/2015/11/02/gta-v-graphics-study-part-2