Beyond3D - Origin of Quake3's Fast InvSqrt()
Published on 29th Nov 2006, written by Rys for Software - Last updated: 21st Mar 2007 Introduction Note! This article is a republishing of something I had up on my personal website a year or so ago before I joined Beyond3D, which is itself the culmination of an investigation started in April 2004. So if timeframes appear a little wonky, it's entirely on purpose! One for the geeks, enjoy. To most f
Understanding Quake’s Fast Inverse Square Root – BetterExplained
An article and research paper describe a fast, seemingly magical way to compute the inverse square root ($1/\sqrt{x}$), used in the game Quake. I'm no graphics expert, but appreciate why square roots are useful. The Pythagorean theorem computes distance between points, and dividing by distance helps normalize vectors. (Normalizing is often just a fancy term for division.) 3D games like Quake divid
Fast inverse square root - Wikipedia
Lighting and reflection calculations, as in the video game OpenArena, use the fast inverse square root code to compute angles of incidence and reflection. Fast inverse square root, sometimes referred to as Fast InvSqrt() or by the hexadecimal constant 0x5F3759DF, is an algorithm that estimates , the reciprocal (or multiplicative inverse) of the square root of a 32-bit floating-point number in IEEE
InvSqrt.dvi
FAST INVERSE SQUARE ROOT CHRIS LOMONT Abstract. Computing reciprocal square roots is necessary in many applications, such as vector normalization in video games. Often, some loss of precision is acceptable for a large increase in speed. This note examines and improves a fast method found in source- code for several online libraries, and provides the ideas to derive similar methods for other functi
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0x5f3759df - a true 'magic number'
http://www.matzmtok.com/blog/?p=451
高速根号計算アルゴリズム
http://ncannasse.fr/blog/fast_inverse_square_root