Whenever I give talks about WebGL and try to describe "real time rendering," I like to start off with with a description of what real time rendering is _not_. [

Whenever I give talks about WebGL and try to describe "real time rendering," I like to start off with with a description of what real time rendering is _not_. [0] The factoid I like to use is: "Toy Story 3 took on average 7 hours to render 1 frame (24 fps), and at most 39 hours." (source [1]) That means if we wanted to render the next frame dynamically based on user input, the user would have to wait on average 7 hours to see the next frame, vs 16.666 ms that we shoot for in real time rendering. If one frame takes on average 7 hours, and there's 24 frames per second, then it take 168 hours or 1 week to render 1 second of video. Better get it right the first time (or have a super computer cluster to do all of that math)! Many corners are cut to achieve something of lesser quality than can be achieved via pre-rendering; we call them "approximations." [0] http://nickdesaulniers.github.io/RawWebGL/#/28 http://nickdesaulniers.github.io/RawWebGL/#/28 [1] http://www.wired.com/2010/05/process_pixar/all/ http://www.wired.com/2010/05/process_pixar/all/