Hello again. I am hoping to get a response this time now that things seem to have quieted down some on the list. I've got a patch that modifies the lattice deformer ever so slightly...it simply adds a new spline option. More info is below. this is a very minor change and I hope it can be accepted and integrated quickly. We are using Blender at NASA Ames as an engineering tool, something many of you may never have expected. However, the lattice deformer is great for doing shape optimization on triangulated surfaces of airplanes and other aerospace geometries. currently I am using Blender to do aerostructural analysis, where we predict the deflection of flexible wings under aerodynamic load (see 787) and actually apply the deflection via Blender. However, the splines available in the lattice deformer are inadequate as coded for our use, so I added a new spline...the Catmull-Rom spline..which is the same as what Blender uses for animation. this does not remove or alter an y previous features, it simply adds a another option.
To whom should I speak about patch files? Thanks. _____ David On May 1, 2013, at 3:12 PM, dl...@me.com wrote: > Hi all. I discussed updating the lattice spline a few months ago. I have > since done some more research and would like to propose a very simple > improvement to the lattice deformer. The current options are "Linear", > "Cardinal", and "Bspline". The Cardinal spline is set to a tension of 0.71 > which can produce very wavy results when the lattice is dense. However, if > we changed the tension to 0.5, the spline becomes the popular Catmull-Rom > spline and produces very nice results, results we can use here at NASA Ames > to deform wings. The Catmull-Rom spline is already being used in other parts > of Blender, so it's natural to include it as an option in the lattice. > > The changes to the code are extremely minor...3-4 source files. 1-2 lines in > most cases, and only 12 or so more in one file with code that looks very > similar to what is already there. I can put together the patch in about an > hour. > > My proposal is this: > > Add "Catmull-Rom" as an option for the spline interpolators in the lattice > deformer. > > > That's it. Quick and simple. Doesn't alter any current functionality, it > simply expands the current number of options from 3 to 4. > > Can such a project be approved? Thanks. > > > > _____ > David > > > > > On Feb 12, 2013, at 3:11 AM, Ton Roosendaal <t...@blender.org> wrote: > >> Hi, >> >> This code and the formula is like 18 years old, i'd welcome someone checking >> on improvements. Rather to make it really good, not just with a button to >> set the interplation value. >> >> Your 'plot' didnt get through... >> >> -Ton- >> >> ------------------------------------------------------------------------ >> Ton Roosendaal Blender Foundation t...@blender.org www.blender.org >> Blender Institute Entrepotdok 57A 1018AD Amsterdam The Netherlands >> >> On 11 Feb, 2013, at 23:26, dl...@mac.com wrote: >> >>> Pardon me if this is the wrong list to send this to. If so, I would >>> appreciate someone pointing me in the right direction. Thanks! >>> >>> >>> The Cardinal spline interpolation for lattices befuddles me. The >>> tension-like variable (fc in the code) is set to 0.71, which I'm guessing >>> is approximately 1/sqrt(2). However, this gives very ugly and wavy results >>> on long straight objects like an airplane wing. In fact, the slopes at the >>> knots is just plain wrong. However, when fc = 0.5, I get very nice >>> cubic-spline-like behavior except at the end points where the code logic >>> just seems to be wrong. Nevertheless, the waviness at the knots is >>> disconcerting in the current distribution of Blender. The plots below show >>> what I mean. >>> >>> >>> >>> >>> Thoughts? Any chance that fc (tension?) variable can be a parameter the >>> user could control? >>> >>> >>> _____ >>> David >>> >>> >>> >>> >>> _______________________________________________ >>> Bf-committers mailing list >>> Bf-committers@blender.org >>> http://lists.blender.org/mailman/listinfo/bf-committers >> >> _______________________________________________ >> Bf-committers mailing list >> Bf-committers@blender.org >> http://lists.blender.org/mailman/listinfo/bf-committers > _______________________________________________ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers
