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Dirk Gregorius

Member Since 24 Apr 2002
Offline Last Active Jul 01 2015 04:00 PM

Topics I've Started

Editing Bezier Splines while maintaining C1 Continuity

20 June 2014 - 07:46 PM

I have constructed a (cubic) Bezier spline from some input points by building a Catmull Rom spline first and then convert it to a Bezier spline. I want to manipulate the individual control vertices now, but maintain C1 continuity.


The best I came up with so far is this:

- If I manipulate a knot I can use the same strategy as used for Catmull Rom splines (e.g. compute the tangent and update also the incoming and outgoing vertex)

- If I manipulate an 'internal' control vertex I might just apply the equal and opposite translation to the corresponding vertex to keep them aligned.


I googled for spline/curve editing/manipulation, but couldn't find anything useful so I was wondering if anyone can point me into the right direction.




Spline Ik and Fullbody Ik

12 June 2014 - 03:52 PM

I am looking for some references on Spline Ik and Fullbody Ik. I found tons of good material on basic Ik solvers like Jacobian methods, CCD, analytical and particle methods, but I failed to find anything about these two topics. I must assume I lost my Google Fu :)


For Spline Ik my understanding is that your are given a bunch of joint pivots and find a curve through all these points. Then while moving the spline control points you reconstruct the bone chain. There are some tricky details for the twist.


Fullbody Ik seems to combine different kinds of Ik solvers (e.g. spline solver for the spine, and maybe analytical methods for arms, etc) and then solve those in some hierarchical way with constraints between the Ik handles.


Any information is welcome! Thanks!

Brute Force OBB Fitting

12 August 2013 - 06:43 PM

I implemented a brute force OBB fitting approach for a vertex cloud and I am thinking about which Euler angles range need to iterate. My intuition says -45 <= (yaw, pitch, roll) <= 45 should be sufficient. Does this make sense?

Brute Force OBB Fitting

12 August 2013 - 06:34 PM


Point inside convex polyhedron defined by planes

19 February 2013 - 10:39 PM

Given a set of planes that define a convex polyhedron. I would need to quickly find an arbitrary point inside the polyhedron. Not necessarily, but ideally the centroid. I want to do this without any plane intersections if possible.