Re: Rotate Vector in XSIMaths

[Alok]

Ah !  a typo: **6.12323399574 is to be multiplied by 10 ^ -17 -------- Original Message -------- Subject: Re: Rotate Vector in XSIMaths Date: Thu, 21 Feb 2013 10:33:37 -0500 From: Alok <alok.gan...@modusfx.com> To: softimage@listproc.autodesk.com +1 to Martin's reply, that is the correct explanation. .Peter you don't have a thing to worry, you are doing everything right, do consider 6.12323399574e-17 as  0.0 Let me explain why: you see the e-17 at the end of number ? That mean the number 6.12323399574 is to be multiplied by 10 ^ 17 or divided by 10 ^ 17. So effectively this is: 6.12323399574 / 1000000000000000000 ~= 0.0000000000000000612323399574 which can be approximately treated as 0. I hope that explains. On 21/02/2013 10:20 AM, Martin Chatterjee wrote: Hi Peter, as far as I see it your result is correct?  The resulting vector should be   [0.0,  0.0,  -1.0] - which is effectively the result of your print statement. in your example vec.Y has a value of 6.12323399574e-17  which essentially is  0.0 (due to floating point math precision). So all is fine - or did I not get your point? Cheers, Martin --        Martin Chatterjee   [ Freelance Technical Director ] [   http://www.chatterjee.de   ] [ https://vimeo.com/chatterjee ]  nbsp;]  On Thu, Feb 21, 2013 at 3:21 PM, Peter Agg <peter....@googlemail.com> wrote: (and yes, rotating [0, 1, 0] by [-90, 0, 0] should actually make make [0, 0, -1]) :) On 21 February 2013 14:15, Peter Agg <peter....@googlemail.com> wrote: Hey all, I'm trying to rotate a vector in a Python Script and seem to be running into an odd block. For example: I want to rotate the vector [0, 1, 0] by [-90, 0, 0], which should make [-1, 0, 0] (and does so if I test in ICE using a Rotate Vector node) but I can't seem to work out how to do this via scripting. What I tried: vec = XSIMath.CreateVector3(0, 1, 0) rot = XSIMath.CreateRotation(XSIMath.DegreesToRadians( -90 ),                              XSIMath.DegreesToRadians( 0 ),                              XSIMath.DegreesToRadians( 0 )) vec.MulByRotationInPlace( rot) print vec.X, vec.Y, vec.Z # 0.0 6.12323399574e-17 -1.0 ...which makes me think that I've misunderstood what MulByRotation does! Any ideas? No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2238 / Virus Database: 2639/5621 - Release Date: 02/21/13