So, yeah, silly question. :) Still haven't dived that deep into matrix maths myself. Thanks for the clarification Grahame! It's appreciated.
Mitch On Tue, Aug 27, 2013 at 5:22 PM, Grahame Fuller <grahame.ful...@autodesk.com > wrote: > T is not an exponent in that formula - rather MT is the transpose of M. > > gray > > From: softimage-boun...@listproc.autodesk.com [mailto: > softimage-boun...@listproc.autodesk.com] On Behalf Of Mitchell Lotierzo > Sent: Tuesday, August 27, 2013 6:15 PM > To: softimage@listproc.autodesk.com > Subject: Re: SI Matrix3 and Maths > > So out of curiosity (and pardon me if this is a silly question), what > exactly is the exponent of 'T' in that equation? I don't seem to see a > definition. > > On Tue, Aug 27, 2013 at 3:38 PM, Matt Lind <ml...@carbinestudios.com > <mailto:ml...@carbinestudios.com>> wrote: > Maggie hasn't been with Softimage for nearly 10 years. What's everybody > else's excuse? > > > Matt > > > > > -----Original Message----- > From: softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com> [mailto: > softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com>] On Behalf Of Grahame Fuller > Sent: Tuesday, August 27, 2013 12:16 PM > To: softimage@listproc.autodesk.com<mailto:softimage@listproc.autodesk.com > > > Subject: RE: SI Matrix3 and Maths > > Maggie. > > gray > > -----Original Message----- > From: softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com> [mailto: > softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com>] On Behalf Of Matt Lind > Sent: Tuesday, August 27, 2013 3:04 PM > To: softimage@listproc.autodesk.com<mailto:softimage@listproc.autodesk.com > > > Subject: RE: SI Matrix3 and Maths > > In a bit of irony, I actually don't know who was in charge of the SDK > guide. > > Matt > > > > > -----Original Message----- > From: softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com> [mailto: > softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com>] On Behalf Of Grahame Fuller > Sent: Tuesday, August 27, 2013 12:02 PM > To: softimage@listproc.autodesk.com<mailto:softimage@listproc.autodesk.com > > > Subject: RE: SI Matrix3 and Maths > > It's been long enough that I can say this. Do you remember who was in > charge of the SDK guide? That's why. > > gray > > -----Original Message----- > From: softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com> [mailto: > softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com>] On Behalf Of Eric Thivierge > Sent: Tuesday, August 27, 2013 2:57 PM > To: softimage@listproc.autodesk.com<mailto:softimage@listproc.autodesk.com > > > Subject: Re: SI Matrix3 and Maths > > Formula? What you talkin' 'bout Willis? > > > Eric Thivierge > =============== > Character TD / RnD > Hybride Technologies > > > On August-27-13 2:54:24 PM, Matt Lind wrote: > > Which begs the question - why is that formula in the user's guide and > > not the sdk guide? > > > > I've wondered about that for years. > > > > Matt > > > > *From:*softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com> > > [mailto:softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com>] *On Behalf Of > > *Grahame Fuller > > *Sent:* Tuesday, August 27, 2013 11:52 AM > > *To:* softimage@listproc.autodesk.com<mailto: > softimage@listproc.autodesk.com> > > *Subject:* RE: SI Matrix3 and Maths > > > > Just to clarify, that's the order of the matrices in the > > multiplication, which in a row-vector world corresponds to performing > > the transformations interactively in the opposite order. > > > > If there's non-uniform scaling involved and hierarchical scaling is > > on, it's more complicated. For the gruesome details, scroll to the > > bottom of this page: > > > http://download.autodesk.com/global/docs/softimage2014/en_us/userguide/index.html?url=files/transforms_ScalingObjects.htm,topicNumber=d30e51306 > . > > > > If there's no non-uniform scaling then everything works out the same > > as for classic scaling. > > > > gray > > > > *From:*softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com> > > <mailto:softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com>> > > [mailto:softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com>] *On Behalf Of *Daniel > > Brassard > > *Sent:* Tuesday, August 27, 2013 2:29 PM > > *To:* softimage@listproc.autodesk.com<mailto: > softimage@listproc.autodesk.com> > > <mailto:softimage@listproc.autodesk.com<mailto: > softimage@listproc.autodesk.com>> > > *Subject:* Re: SI Matrix3 and Maths > > > > BTW, the order of operation on the matrices is important. For > > Softimage you scale, rotate then translate (SRT like the order in the > > MCP, easy way to remember). Any other way and you will have > > unpredictable results. > > > > On Tue, Aug 27, 2013 at 2:12 PM, Daniel Brassard > > <dbrassar...@gmail.com<mailto:dbrassar...@gmail.com> <mailto: > dbrassar...@gmail.com<mailto:dbrassar...@gmail.com>>> wrote: > > > > A pretty good explanation of row vector and transform Matrix here. > > > > http://msdn.microsoft.com/en-us/library/windows/desktop/bb206269(v=vs. > > 85).aspx > > > > On Tue, Aug 27, 2013 at 1:39 PM, Grahame Fuller > > <grahame.ful...@autodesk.com<mailto:grahame.ful...@autodesk.com> > <mailto:grahame.ful...@autodesk.com<mailto:grahame.ful...@autodesk.com>>> > wrote: > > > > I'm pretty sure it's the row versus column vector issue. In a > > nutshell, most of the CG world, including Softimage, treats vectors as > > rows, i.e., 1x3 matrices. The rest of the world, including most > > references you'll find for math, physics, robotics, etc., treats > > vectors as columns, i.e., 3x1 matrices. > > > > In a row-vector world, you construct your transform by inserting your > > X,Y,Z basis vectors into a matrix as rows. The order of multiplication > > for transforms is Mchild x Mparent, and when multiplying a vector and > > matrix the vector goes on the left and the matrix on the right. > > > > In a column-vector world, it's the opposite. You construct your > > transform by inserting your X,Y,Z basis vectors into a matrix as > > columns. The order of multiplication for transforms is Mparent x > > Mchild, and when multiplying a vector and matrix the vector goes on > > the right and the matrix on the left. > > > > In particular, note that the row-vector transform is transposed > > (mirrored across the diagonal) from the column-vector transform. So if > > the formulas for your individual rotation matrices matX, matY, and > > matZ came from a reference that uses column-vectors, you need to > > transpose the matrices. > > > > To calculate the various rotation orders, you just need to multiply > > the matrices in different orders. In a row-vector world, you use > > reverse order, for example, if you want XYZ order then you calculate > > matZ x matY x matX. Luckily matrix multiplication is the same in both > > row-vector and column-vector worlds, so you can save some processor > > time by figuring it out long-hand and stuffing the final values into > > the full transform matrix directly, like in the code sample you > > showed, but of course it's easy to make a typo or other mistake. > > > > gray > > > > From: softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com> > > <mailto:softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com>> > > [mailto:softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com> > > <mailto:softimage-boun...@listproc.autodesk.com<mailto: > softimage-boun...@listproc.autodesk.com>>] On Behalf Of Eric > > Thivierge > > Sent: Monday, August 26, 2013 8:21 PM > > To: softimage@listproc.autodesk.com<mailto: > softimage@listproc.autodesk.com> > > <mailto:softimage@listproc.autodesk.com<mailto: > softimage@listproc.autodesk.com>> > > Subject: Re: SI Matrix3 and Maths > > > > Thanks Raf I saw that today. It's a problem somewhere with my matrix > > multiplication I think. Tried a bunch of different combos but I'm > > thinking it's what Matt touched on either the row / column mixing or a > > mistake in the shorthand somewhere. > > > > -------------------------------------------- > > Eric Thivierge > > http://www.ethivierge.com > > > > On Mon, Aug 26, 2013 at 8:15 PM, Raffaele Fragapane > > <raffsxsil...@googlemail.com<mailto:raffsxsil...@googlemail.com> > > <mailto:raffsxsil...@googlemail.com<mailto:raffsxsil...@googlemail.com > >><mailto:raffsxsil...@googlemail.co<mailto:raffsxsil...@googlemail.co> > > m <mailto:raffsxsil...@googlemail.com<mailto:raffsxsil...@googlemail.com > >>>> > > wrote: > > The rotation order matters. > > It's as simple as each rotation pushing a gimbal along by a linear > > distance of trigonometric functions of that angle in turns, in the > > rotation order... order. > > Wikipedia has the matricial forms: > > http://en.wikipedia.org/wiki/Rotation_matrix#Basic_rotations > > What's not working from that? Or if you haven't looked at it, shame on > > you! > > > > > > > >
