"Carl Hoff" <hof### [at] wtnet> wrote in message news:4032ba6b@news.povray.org...
> > > What you asked about the front/back or leading/trailing
> > > sides is simply a matter of pulling a vector from out of the
> > > spline by its time (or t) value. Such as I did to place the
> > > light_source ahead of center. It's just any amount +/- of
> > > the clock, in that example. And then the question about
> > > going up walls would be done by adding y values to the
> > > sphere_sweep and spline vectors.
> >
> > Thanks... that sounds simple enough.
>
> Ummm... it just hit me that only takes care of forward and
> back.  In 2D that's fine but if my bike climbs walls, I can
> point it forward but how do I know the wheels will be on
> the floor (or wall in this case)?  Think of unit vectors pointing
> in the x/forward direction, y/upward direction, and z/left
> direction coming from the point that's traveling along the
> spline.  The above tells me how to define x but if I can climb
> walls or fly I need to know how to find y or z.  One will
> give me the other but at the moment I'm not sure how to
> find either.

You might be thinking too hard and overlooking the simplicity of it. The
splines have all three axes. Or I'm not thinking hard enough. Maybe you're
needing a way to create the path based on what the room shape is and
obstacles in it? If so, then 'trace' is probably the answer. That could be
applied to sense surroundings, but it can slow up animations.

I had figured you would be plotting out the path yourself though, in
advance. If that were the case, all you'd do is set the vectors to include
each value, i.e. <0,0,0> to <1,0,0> to <1,1,0> moves forward (+x) then stays
at x*1 but moves up y*1.

Hopefully I'm still shedding some light.

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