Angus Dorbie (dorbie++at++multipass.asd.sgi.com)
Wed, 2 Jul 1997 15:19:40 -0700
See my posting there.
Cheers,Angus.
On Jul 1, 2:42pm, WILLIAM_MARINELLI++at++ntsc.navy.mil wrote:
> Subject: Curved Ocean
> The issue I would like to address is the idea of rendering ships on
> the horizon if they are viewed from a periscope. On a flat ocean, they
> look hokey since in real life they should sink down into the horizon.
>
> My first approach was to simply sink the ships into the ocean based on
> their distance from the eyepoint and the curvature of the earth. This
> did lower the ships, but the effect had a hokeyness all its own: There
> would be water surrounding the partially sunken ship.
>
> My next kluge was to manipulate the far clip plane so that there was
> no water behind the partially sunken ship. But what if there was more
> than one ship out there and the ships were at different distances from
> the eyepoint.
>
> Enough about my problem. I am wondering about the possibility of
> modeling the ocean as a curved surface - perhaps a NURB or a set of
> NURBS. Any ideas of the feasibility of doing that? (I do recall that
> OpenGL demo that generates a heart shaped object from NURBS - I think
> it was a glu call. And the relationship of the control points to the
> curve was not clear in the way it was coded - at least not clear to
> me.) Of course, if this were done, the ships would have to placed on
> the nurb based ocean to produce this sinking on the horizon effect. I
> think that would be an easy calculation.
>
> The other option that comes to mind with a flat ocean is to render the
> ships correctly out to a certain point near the far clip plane. At
> that point, depending on how far they are supposed to be away from the
> eyepoint, then scale them and sink them to get the right perspective.
>
> Any thoughts on this sort of thing?
>
>
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>-- End of excerpt from WILLIAM_MARINELLI++at++ntsc.navy.mil
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