[Maya-Python] Re: API: Custom Spline IK (or Motion Path)
Hard , to tell much i have build my nodes differently: The core concept was that the curve is a temporal system: there is a start and an end ( you will often see in SIGGRAPH paper the u parameter named as the variable *t* ). I dont try to bundle all element in one node: some data can be store and update upstream. so my node compute a matrix at a curve parameter value and the end object is used to extract a twist value. This extraction is done by a separate node . it doesn't matter if you have 7 full spin on the twist axis: your motion path node drive your joint and even with 180/-180 degree range the orientation will be correct Le lundi 12 novembre 2012 11:00:31 UTC+1, Roy Nieterau a écrit : 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
RE: [Maya-Python] Re: API: Custom Spline IK (or Motion Path)
Sounds exactly like what I would need. So one would for example: 1. Get the point on curve (MFnNurbsCurve.getPointAtParam) 2. Create the matrix for that point (where do you get the rotation from?, since the tangent and normal give unpredictable results, although I haven't seen them working the way I actually wanted) We know that the matrix would always aim towards a next point on the curve (aiming along the curve). The upVector would be the twist, yet there's no default rotation to which we can add twisting rotation along the aimVector (changing the upVector and the orthogonal vector of both upVector and aimVector). 3. End object extract a twist value: by extracting it's rotation along a certain local axis, right? 4. Apply the twist 5. Done. As you can see I'm having a hard time visualing or thinking through points 2 and 3. Maybe I'm too much of a beginner for this, hehe. :) Thanks again! -Roy Date: Fri, 16 Nov 2012 01:57:55 -0800 From: cedricbazil...@gmail.com To: python_inside_maya@googlegroups.com Subject: [Maya-Python] Re: API: Custom Spline IK (or Motion Path) Hard , to tell much i have build my nodes differently: The core concept was that the curve is a temporal system: there is a start and an end ( you will often see in SIGGRAPH paper the u parameter named as the variable t ). I dont try to bundle all element in one node: some data can be store and update upstream. so my node compute a matrix at a curve parameter value and the end object is used to extract a twist value. This extraction is done by a separate node . it doesn't matter if you have 7 full spin on the twist axis: your motion path node drive your joint and even with 180/-180 degree range the orientation will be correct Le lundi 12 novembre 2012 11:00:31 UTC+1, Roy Nieterau a écrit :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
[Maya-Python] Re: API: Custom Spline IK (or Motion Path)
I use the tangent and it is really robust: its the curve normal that can break with sharp turn. But my node drives helper/cross section joint and i have better result with tangent than point at the next point on the curve. Perhaps try to use a nurbssurface ribbon and than once you are comfortable with that you can start massaging vector and matrix? Le lundi 12 novembre 2012 11:00:31 UTC+1, Roy Nieterau a écrit : 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
