Comments on: Visualizing Floats http://cowboyprogramming.com/2007/01/05/visualizing-floats/ Game Development and General Hacking by the Old West Tue, 20 Jul 2010 15:03:31 +0000 http://wordpress.org/?v=2.9.1 hourly 1 By: burning calories http://cowboyprogramming.com/2007/01/05/visualizing-floats/comment-page-1/#comment-144111 burning calories Wed, 06 Jan 2010 17:38:52 +0000 http://cowboyprogramming.com/?p=40#comment-144111 thanks a lot for the interesting and informative post. thanks a lot for the interesting and informative post.

]]> By: dog health information http://cowboyprogramming.com/2007/01/05/visualizing-floats/comment-page-1/#comment-138304 dog health information Sat, 21 Nov 2009 23:27:14 +0000 http://cowboyprogramming.com/?p=40#comment-138304 I think commenter erik lien is right. Might want to doublecheck that Mike. I think commenter erik lien is right. Might want to doublecheck that Mike.

]]> By: Catherine Ellis http://cowboyprogramming.com/2007/01/05/visualizing-floats/comment-page-1/#comment-135186 Catherine Ellis Mon, 26 Oct 2009 00:54:10 +0000 http://cowboyprogramming.com/?p=40#comment-135186 Enjoyed reading this article, nice one Mick Enjoyed reading this article, nice one Mick

]]> By: Любитель мини-игр http://cowboyprogramming.com/2007/01/05/visualizing-floats/comment-page-1/#comment-95602 Любитель мини-игр Thu, 19 Mar 2009 13:42:07 +0000 http://cowboyprogramming.com/?p=40#comment-95602 Great article, Mick! Great article, Mick!

]]> By: Erik Lien http://cowboyprogramming.com/2007/01/05/visualizing-floats/comment-page-1/#comment-92950 Erik Lien Tue, 10 Mar 2009 03:07:51 +0000 http://cowboyprogramming.com/?p=40#comment-92950 In your FLOATS vs. INTEGERS part you got the precision wrong. Remember the implicit bit in floating point numbers. 32 bit floats have 24 bits of precision. (If you want to store integers in a float, you can accurately represent all integers from 0 to 16777216. As you said, between any 2 powers of two there are 8388608 possible numbers, so from 8388608 to 16777216 you have all the needed 8388608 integers. From 0 to 8388608 you also have all the integers plus lots of numbers inbetween. From 16777216 to 33554432 you only have the even integers) So your precision up to 2^32mm becomes 256mm. Using the sign bit (by centering the world, as mentioned), your precision increases to 128mm. Still not great, but much more useful than 512mm. And you could use doubles :) In your FLOATS vs. INTEGERS part you got the precision wrong. Remember the implicit bit in floating point numbers. 32 bit floats have 24 bits of precision. (If you want to store integers in a float, you can accurately represent all integers from 0 to 16777216. As you said, between any 2 powers of two there are 8388608 possible numbers, so from 8388608 to 16777216 you have all the needed 8388608 integers. From 0 to 8388608 you also have all the integers plus lots of numbers inbetween. From 16777216 to 33554432 you only have the even integers)

So your precision up to 2^32mm becomes 256mm. Using the sign bit (by centering the world, as mentioned), your precision increases to 128mm. Still not great, but much more useful than 512mm. And you could use doubles :)

]]> By: „¥â᪨¥ ¨£àë http://cowboyprogramming.com/2007/01/05/visualizing-floats/comment-page-1/#comment-77026 „¥â᪨¥ ¨£àë Sun, 18 Jan 2009 17:43:10 +0000 http://cowboyprogramming.com/?p=40#comment-77026 Great article! Very nice Great article! Very nice

]]> By: Sean T. McBeth http://cowboyprogramming.com/2007/01/05/visualizing-floats/comment-page-1/#comment-3066 Sean T. McBeth Mon, 13 Aug 2007 13:18:31 +0000 http://cowboyprogramming.com/?p=40#comment-3066 I have similar concerns about using floats as color component values in HDRI. Color is equally dependant on the relative value between two "consecutive" colors as it is on the absolute value of that color. If there isn't enough resolution in our color data, then we end up with nasty gradients. As you probably already know, HDRI seeks to use values outside of the [0.0 1.0] range in order to represent light saturation. Almost a full 1/8th of all usable 32b floating point values (because of the NaN and inf definition, there are only (2^32 - 2^24) usable values, and only half of them are positive) fall in the [0.0 1.0] range, and as you demonstrated, the values get much worse the further out you get. It's unfortunate that the latest graphics hardware is now hardwired to exclusively use floats in shader operations. I have similar concerns about using floats as color component values in HDRI. Color is equally dependant on the relative value between two “consecutive” colors as it is on the absolute value of that color. If there isn’t enough resolution in our color data, then we end up with nasty gradients.

As you probably already know, HDRI seeks to use values outside of the [0.0 1.0] range in order to represent light saturation. Almost a full 1/8th of all usable 32b floating point values (because of the NaN and inf definition, there are only (2^32 – 2^24) usable values, and only half of them are positive) fall in the [0.0 1.0] range, and as you demonstrated, the values get much worse the further out you get.

It’s unfortunate that the latest graphics hardware is now hardwired to exclusively use floats in shader operations.

]]> By: Mick West http://cowboyprogramming.com/2007/01/05/visualizing-floats/comment-page-1/#comment-591 Mick West Tue, 03 Apr 2007 20:59:01 +0000 http://cowboyprogramming.com/?p=40#comment-591 I don't know what I was thinking. I must be getting old. I don’t know what I was thinking. I must be getting old.

]]> By: Paul Robinson http://cowboyprogramming.com/2007/01/05/visualizing-floats/comment-page-1/#comment-588 Paul Robinson Tue, 03 Apr 2007 18:39:48 +0000 http://cowboyprogramming.com/?p=40#comment-588 That came up at a meeting here as well - adjusting the scale won't do a thing since all entities are scaled equally, so the accuracy you have will be scaled as well. I guess you could try scaling to a boundary to maximize the accuracy a little - ie. center your world, but make sure the extents are at -1 & 1, say, and not -0.9 & 0.9. That came up at a meeting here as well – adjusting the scale won’t do a thing since all entities are scaled equally, so the accuracy you have will be scaled as well. I guess you could try scaling to a boundary to maximize the accuracy a little – ie. center your world, but make sure the extents are at -1 & 1, say, and not -0.9 & 0.9.

]]> By: Mick West http://cowboyprogramming.com/2007/01/05/visualizing-floats/comment-page-1/#comment-184 Mick West Wed, 28 Feb 2007 02:56:49 +0000 http://cowboyprogramming.com/?p=40#comment-184 Well, drat! That is not intuitively obvious. I'll have to write a follow-up now. Thanks Peter. Well, drat! That is not intuitively obvious. I’ll have to write a follow-up now. Thanks Peter.

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