Hey John, Thanks for the quick replies. I'm not sure what you mean with the following: * * *Zero out whichever axis is the aim-axis in your 'up vector', then convert that vector into an MMatrix. Now you have a matrix you can multiply your existing aimed-joint-matrix by to twist it.*
Why would that be helpful or what would those steps produce? If I zero out the up vector and convert that into an MMatrix ain't I creating a zero matrix? (Default matrix) -Roy On Monday, November 12, 2012 4:34:14 PM UTC+1, JP wrote: > > I would think about it like this: for each point/joint along the curve, > you should have some sort of 'up vector'. You could get that a number of > ways - a start/end 'twist' amount, an array of 'up' target objects for each > joint, etc. The end result is that each point along the curve should have > a vector to some other target to help determine the twist. > > Next, you'll need to know what your joint's aim-axis is. The built-in > spline ik node assumes an 'x' aim axis (which blows), but you could have an > input attr for the aim axis. > > Zero out whichever axis is the aim-axis in your 'up vector', then convert > that vector into an MMatrix. Now you have a matrix you can multiply your > existing aimed-joint-matrix by to twist it. > > I think it would be nice to have an array of world matrices for > up-objects, which you would plug the controls for the spline into. You > could get the closest point along the curve for each and treat a particular > axis as the 'up vector' for that point along the curve, then interpolate > between them. > > > On Mon, Nov 12, 2012 at 7:13 AM, Roy Nieterau > <roy_ni...@hotmail.com<javascript:> > > wrote: > >> Hey JP, >> >> Actually I know how to get the point on the curve. Aiming at the next >> joint is also a relatively easy step. >> >> On the other hand knowing/calculating the up vector for the aim is >> something I'm unaware of how to do it. How did you solve/calculate the up >> vector for the aim constraint? >> >> I'm especially interested in allowing a twisting motion along the curve. >> >> -Roy >> >> ------------------------------ >> CC: python_in...@googlegroups.com <javascript:> >> From: jspa...@gmail.com <javascript:> >> Subject: Re: [Maya-Python] API: Custom Spline IK (or Motion Path) >> Date: Mon, 12 Nov 2012 07:08:48 -0800 >> To: python_in...@googlegroups.com <javascript:> >> >> >> Hey Roy, >> >> I've done a sort of 'manual' setup like this by writing a 'pointAtArclen' >> node and then wiring the rest with existing nodes. In my case I used aim >> constraints for each joint, but you can do something similar within your >> solver- get the orientation by figuring out where each joint needs to be on >> the curve and what the vector would be if you were aiming each joint at the >> next. >> >> -JP >> >> Sent from my iPhone >> >> On Nov 12, 2012, at 2:00 AM, Roy Nieterau <royni...@gmail.com<javascript:>> >> wrote: >> >> Hey Guys, >> >> I'm looking into creating a custom Stretchy Spline IK setup that doesn't >> pop (over & under extends in extreme situations). >> But I seem to be unable to wrap my head around how to calculate >> orientations on points on the curve. >> Since the points on the curve don't have any orientation (well, they do >> have tangents or something like that?) I have no clue on how to actually >> start with this. >> >> My main references of tools in Maya would be the Motion Path and the >> Spline IK (with Advanced Twist controlled by a start and end object). >> If anybody has any starting points for this it would be greatly >> appreciated! >> >> Thanks in advance. >> >> Regards, >> Roy >> >> -- >> view archives: http://groups.google.com/group/python_inside_maya >> change your subscription settings: >> http://groups.google.com/group/python_inside_maya/subscribe >> >> >> -- >> view archives: http://groups.google.com/group/python_inside_maya >> change your subscription settings: >> http://groups.google.com/group/python_inside_maya/subscribe >> >> -- >> view archives: http://groups.google.com/group/python_inside_maya >> change your subscription settings: >> http://groups.google.com/group/python_inside_maya/subscribe >> > > > > -- > John Patrick > 404-242-2675 > jspa...@gmail.com <javascript:> > http://www.canyourigit.com > -- view archives: http://groups.google.com/group/python_inside_maya change your subscription settings: http://groups.google.com/group/python_inside_maya/subscribe
