Thanks for the replies everyone, I think I get it now
In: 24
**Old way:** Take a bunch of triangles, “project,” them onto the 2D screen (similar to how you’d draw a “3D cube,” on a piece of paper) and then color in the 2D triangles. There’s tons of smoke and mirrors, and things like surface lighting and shadows are two completely different techniques mushed together to make it look like it’s real lighting. Hacks on top of hacks on top of hacks, but we’ve managed to get things looking pretty realistic over the years.
**Raytracing**: You specify the physical properties of a surface (rough surfaces scatter light, shiny surfaces don’t, glass bends the light as it passes through, red surfaces absorb green and blue light, etc.) and then you just shoot light rays out and let them do their thing. All the hacks that we’ve had to develop over the years we basically just get for free with raytracing, and even some of the things like realtime bounce lighting, reflections, and glass refraction that have been almost impossible to do before (at least well).
It’s the last major step in realistic graphics. Problem is, it requires thousands to millions of rays to be simulated each frame, which as you can imagine requires a *lot* of processing power. Movies can wait days for a single frame to render, but games can’t, so it’s been used in movies for 20 years, but we’re just now becoming capable of running it in real-time for video games.
SOURCE: I’m a 3D graphics developer, AMA.
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