thanx!
this is helpful
For finally setting the rotation i am using the (maim) matrix-aim
function, but the birds are still flipping over their backs from time to
time
I've been reading on quaternions but this is still beyond my
understanding of 3d math.
I've build each birdy according to a struct:
(define-struct Birdy (
(pos #:mutable) ; position vector
(vel #:mutable) ; velocity vector
(mass #:mutable) ; const
....
(Oforward #:mutable) ; local x vector
(Oup #:mutable) ; local y vector
(Oside #:mutable); local z vector
...
(body) ; prim
)
my failsafe would be to get the orientation from the struct-list of
another Birdy
But with this I can get the local orientation-axisses of an object that
is not build with these struct parameters!
forward-orientation:
(vtransform-rot (vector 1 0 0) (with-primitive p (get-global-transform)))
up-orientation:
(vtransform-rot (vector 0 1 0) (with-primitive p (get-global-transform)))
side-orientation:
(vtransform-rot (vector 0 0 1) (with-primitive p (get-global-transform)))
greets and thanx, Rob
hi Rob,
some starting pics: http://www.flickr.com/photos/superrobber/4305067091/
looks really nice. congrats.
i've tried the (vtransform-rot) but with this function somehow i just
can't get the rotation out of the (get-transform) matrix
the manual says it's kinda ment for use with normals ?
i believe you can get the direction vector like this:
(define (global-dir p)
(vtransform-rot (vector 0 1 0)
(with-primitive p
(get-global-transform))))
; to draw it
(let ([dir (global-dir p)])
(with-primitive (build-ribbon 2)
(hint-unlit)
(hint-wire)
(pdata-set! "p" 0 (vector 0 0 0))
(pdata-set! "p" 1 (vmul dir 5))))
but i'm not sure that this would be very useful in your case, because
this is just a direction vector and not a rotation vector. if you want
the rotation angles, you can try (matrix->euler). but since you want
to interpolate between rotation matrices, you might need quaternions.
best,
gabor
