| Quaternion spherical interpolation in PV-Wave [message #63550] |
Tue, 11 November 2008 14:18 |
ez569x
Messages: 2
Registered: November 2008
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Junior Member |
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I have been been a user of PV-Wave for the last seven years. Let me
say here that without this newsgroup's help, I probably wouldn't have
lasted seven months. I've learned a great deal from all the valuable
posts and been inspired to implement many routines. It's time to
donate back.
PV-Wave doesn't have any quaternion routines. Craig Markwardt does.
I've implemented his routines, but the only one that needed some
tweaking was QTERP. Thanks to Craig for validating my results.
function qterp, t0,q0,t1,qdiff=qdiff,reset=reset,slerp=slerp
; This function has been modified for implementation
; in PV-Wave from the original written by Craig Markwardt.
; Many thanks to him for his help verifying this implementation.
; All other quaternion routines are as originally written.
nq=n_elements(q0)/4
if nq eq 0 then begin
print,'no q input, stopping...'
return, -1
endif
if nq eq 1 then return,rebin(reform(q0,4,1),4,n_elements(t1))
if keyword_set(slerp) then begin
if n_elements(qdiff)/4 ne nq-1 or keyword_set(reset) then begin
qdiff=qtmult(q0(*,0:nq-2),/inv,q0(*,1:*))
wh=where(qdiff(3,*) lt 0,ct)
if ct gt 0 then qdiff(*,wh)=qdiff(*,wh)
endif
ii=floor(mgh_locate(t0,xout=t1)) < (nq-2) > 0 ; mark hadfield
hh=(t1-t0(ii)/(t0(ii+1)-t0(ii))
return,qtmult(q0(*,ii),qtpow(qdiff(*,ii),hh))
endif
q1=(q0(*,0)#t1)*0
for i=0,3 do q1(i,*)=spline(t0,q0(i,*),t1)
tot=sqrt(total(q1^2,d=0))
for i=0,3 do q1(i,*)=q1(i,*)/tot
return,q1
end
Regards,
SpinMan
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