Invisible Deletions: The Architectural Cheat of Occlusion Culling

If a video game rendered every single highly detailed object in a massive city simultaneously, the graphics card would instantly overheat and shut down. To survive this immense mathematical burden, game engines employ a brilliant, invisible optimization technique: Occlusion Culling. Unlike frustum culling (which deletes objects that are behind the player's camera), occlusion culling deletes objects that are physically in front of the camera but currently hidden behind another solid object. If you are standing in an alleyway staring at a brick wall, the engine actively identifies that the entire bustling street on the other side of that wall is blocked from your vision. In a fraction of a millisecond, the game completely deletes the street, the cars, and the people from the processor's memory, only generating them again the instant you peek around the corner. This book explores the intense spatial math required to constantly draw and erase reality at sixty frames per second. We analyze the glitches that occur when this system misfires, causing entire buildings to pop into existence out of thin air. Discover the ultimate digital illusion. Understand how virtual worlds maintain their breathtaking beauty by aggressively deleting everything you cannot currently see.