QUAKE 3 INVERSE SQUARE ROOT CODE

The resulting mess is turned back into a decimal number in the reverse way, which somehow requires merely one iteration of Newton's Method to be accurate enough for a first person game engine.

QUAKE 3 INVERSE SQUARE ROOT CODE

Fast inverse square root skips several iterations of Newton's Method by reinterpreting a decimal number's data as pure integers (which also makes it include a bunch of data used for, say, tracking the decimal point), cutting off the last Bit (turning it into a seemingly unrelated number, and probably not valid data for decimals), and then subtracting that from random ass hexadecimal number. In the source code of the game Quake III a very different approach is found that uses a mysterious approximation method. Usefulness of the calculation is mostly given if you try to normalize a vector quickly. Alogrithm is taken from the game Quake III. A fast yet slightly inaccurate algorithm to calculate the inverse square root of a float number. What TFA calls 'inverse square root' is really 'inverse of the square root', a small but significant difference. A fast algorithm to calculate the inverse of a square root stolen from Quake III. Of course, this is the and we don't have the CPU power for that shit. You are correct, the inverse to xn is x(1/n), from which it follows that the inverse to a square root is the inverse inverse square, or just square. 0 0 'Assassin2107 42 points 3 days In the source code for Quake 3 Arena, there's a function called fast inverse square root, where the devs use some bit manipulation: = * (long * ) &y evil floating point bit level hacking i = Ox5f3759df - (i 1 what the fuck? embed save parent report giveaward reply NexusOtter 3 days ago For those who don't want to read the entire wiki article: This function avoids using Newton's Method, an accurate, but expensive way to calculate the inverse square root of a number, that works by constantly reapplying the method.

'Assassin2107 42 points 3 days In the source code for Quake 3 Arena, there's a function called fast inverse square root, where the devs use some bit manipulation: = * (long * ) &y evil floating point bit level hacking i = Ox5f3759df - (i 1 what the fuck? embed save parent report giveaward reply NexusOtter 3 days ago For those who don't want to read the entire wiki article: This function avoids using Newton's Method, an accurate, but expensive way to calculate the inverse square root of a number, that works by constantly reapplying the method.

Quake 3 inverse square root