1 ! Copyright (C) 2010 Erik Charlebois
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: arrays combinators grouping kernel math
4 math.combinatorics math.polynomials math.vectors sequences ;
8 :: bernstein-polynomial-ith ( n i -- p )
9 n i nCk { 0 1 } i p^ { 1 -1 } n i - p^ p* n*p ;
11 :: hermite-polynomial ( p0 m0 p1 m1 -- poly )
14 -3 p0 * -2 m0 * + 3 p1 * + m1 neg +
15 2 p0 * m0 + -2 p1 * + m1 +
18 :: kochanek-bartels-coefficients ( tension bias continuity -- s1 d1 s2 d2 )
22 [ 1 continuity + * * 2 / ]
23 [ 1 continuity - * * 2 / ] 2bi
27 [ 1 continuity - * * 2 / ]
28 [ 1 continuity + * * 2 / ] 2bi
31 :: kochanek-bartels-tangents ( points m0 mn c1 c2 -- tangents )
33 first3 :> ( pi-1 pi pi+1 )
41 :: <bezier-curve> ( control-points -- polynomials )
44 [ first length [ { 0 } ] replicate ]
47 control-points [| pt i |
48 n i bernstein-polynomial-ith :> poly
50 j acc [ v poly n*p p+ ] change-nth
55 :: <cubic-hermite-curve> ( p0 m0 p1 m1 -- polynomials )
65 : (cubic-hermite-spline) ( point-in-out-triplets -- polynomials-sequence )
67 first2 [ first2 ] [ [ first ] [ third ] bi ] bi* <cubic-hermite-curve>
71 : <cubic-hermite-spline> ( point-tangent-pairs -- polynomials-sequence )
72 2 clump [ first2 [ first2 ] bi@ <cubic-hermite-curve> ] map ;
74 :: <kochanek-bartels-curve> ( points m0 mn tension bias continuity -- polynomials-sequence )
75 tension bias continuity kochanek-bartels-coefficients :> ( s1 d1 s2 d2 )
77 [ s1 s2 kochanek-bartels-tangents ]
78 [ d1 d2 kochanek-bartels-tangents ] 3bi :> ( in out )
79 points in out [ 3array ] 3map (cubic-hermite-spline) ;
81 : <catmull-rom-spline> ( points m0 mn -- polynomials-sequence )
82 0 0 0 <kochanek-bartels-curve> ;