[Bf-committers] lattice spline interpolation

[Ton Roosendaal]

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-

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Ton Roosendaal  Blender Foundation   ton at blender.org    www.blender.org
Blender Institute   Entrepotdok 57A  1018AD Amsterdam   The Netherlands

On 11 Feb, 2013, at 23:26, dlr13 at 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
> 
> 
> 
> 
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