Comments on: Understanding Quake’s Fast Inverse Square Root http://betterexplained.com/articles/understanding-quakes-fast-inverse-square-root/ Learning shouldn't hurt. Let's share the insights that made difficult ideas click. Fri, 20 Nov 2009 14:09:06 -0800 http://wordpress.org/?v=2.8.4 hourly 1 By: Paul Duffy http://betterexplained.com/articles/understanding-quakes-fast-inverse-square-root/#comment-251712 Paul Duffy Sat, 05 Sep 2009 16:42:39 +0000 http://betterexplained.com/articles/understanding-quakes-fast-inverse-square-root/#comment-251712 Bit of a correction. Normalising is not actually a 'fancy term for division'. A vector has an exact length of 1, that is, sqrt(x^2+y^2+z^2) = 1. The normalisation process takes a scalar, like a vector but with no definition of how long it should be, and makes it a vector of the same direction. It's important for things like lighting in computer graphics (you've heard of normal maps, right?), even phong shading wouldn't work without it. Bit of a correction. Normalising is not actually a ‘fancy term for division’. A vector has an exact length of 1, that is, sqrt(x^2+y^2+z^2) = 1. The normalisation process takes a scalar, like a vector but with no definition of how long it should be, and makes it a vector of the same direction.

It’s important for things like lighting in computer graphics (you’ve heard of normal maps, right?), even phong shading wouldn’t work without it.

]]> By: SAWP > Fast InvSqrt using union http://betterexplained.com/articles/understanding-quakes-fast-inverse-square-root/#comment-239199 SAWP > Fast InvSqrt using union Mon, 04 May 2009 21:51:29 +0000 http://betterexplained.com/articles/understanding-quakes-fast-inverse-square-root/#comment-239199 [...] [3] http://betterexplained.com/articles/understanding-quakes-fast-inverse-square-root/ convert this post to pdf. Tags: [ Sem categoria ] | [ Veja este post em PDF: ] [...] [...] [3] http://betterexplained.com/articles/understanding-quakes-fast-inverse-square-root/ convert this post to pdf. Tags: [ Sem categoria ] | [ Veja este post em PDF: ] [...]

]]> By: ekzept http://betterexplained.com/articles/understanding-quakes-fast-inverse-square-root/#comment-220485 ekzept Mon, 05 Jan 2009 05:39:38 +0000 http://betterexplained.com/articles/understanding-quakes-fast-inverse-square-root/#comment-220485 Indeed, a few terms of the Newton-Raphson method is how most hardware does square root, so adapting that for an inverse square root function is similar. However, for general functions there are better ways. See the HANDBOOK OF MATHEMATICAL FUNCTIONS by Abramowitz and Stegun. Indeed, a few terms of the Newton-Raphson method is how most hardware does square root, so adapting that for an inverse square root function is similar. However, for general functions there are better ways. See the HANDBOOK OF MATHEMATICAL FUNCTIONS by Abramowitz and Stegun.

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