factor/basis/math/quaternions/quaternions.factor

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Factor

! Copyright (C) 2005, 2010 Joe Groff, Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
USING: arrays combinators kernel locals math math.functions
math.libm math.order math.vectors sequences ;
IN: math.quaternions
: q+ ( u v -- u+v )
v+ ; inline
: q- ( u v -- u-v )
v- ; inline
<PRIVATE
GENERIC: (q*sign) ( q -- q' )
M: object (q*sign) { -1 1 1 1 } v* ; inline
PRIVATE>
: q* ( u v -- u*v )
{
[ [ { 1 0 0 0 } vshuffle ] [ { 1 1 2 3 } vshuffle ] bi* v* ]
[ [ { 2 1 2 3 } vshuffle ] [ { 2 0 0 0 } vshuffle ] bi* v* v+ ]
[ [ { 3 2 3 1 } vshuffle ] [ { 3 3 1 2 } vshuffle ] bi* v* v+ ]
[ [ { 0 3 1 2 } vshuffle ] [ { 0 2 3 1 } vshuffle ] bi* v* v- ]
} 2cleave (q*sign) ; inline
GENERIC: qconjugate ( u -- u' )
M: object qconjugate ( u -- u' )
{ 1 -1 -1 -1 } v* ; inline
: qrecip ( u -- 1/u )
qconjugate dup norm-sq v/n ; inline
: q/ ( u v -- u/v )
qrecip q* ; inline
: n*q ( n q -- r )
n*v ; inline
: q*n ( q n -- r )
v*n ; inline
: n>q ( n -- q )
0 0 0 4array ; inline
: n>q-like ( c exemplar -- q )
[ 0 0 0 ] dip 4sequence ; inline
: c>q ( c -- q )
>rect 0 0 4array ; inline
: c>q-like ( c exemplar -- q )
[ >rect 0 0 ] dip 4sequence ; inline
! Euler angles
<PRIVATE
: (euler) ( theta exemplar shuffle -- q )
swap
[ 0.5 * [ fcos ] [ fsin ] bi 0.0 0.0 ] [ call ] [ 4sequence ] tri* ; inline
PRIVATE>
: euler-like ( phi theta psi exemplar -- q )
[ [ ] (euler) ] [ [ swapd ] (euler) ] [ [ rot ] (euler) ] tri-curry tri* q* q* ; inline
: euler ( phi theta psi -- q )
{ } euler-like ; inline
:: slerp ( q0 q1 t -- qt )
q0 q1 vdot -1.0 1.0 clamp :> dot
dot facos t * :> omega
q1 dot q0 n*v v- normalize :> qt'
omega fcos q0 n*v omega fsin qt' n*v v+ ; inline