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deepsender

OpenGL Far-clipping and very distant objects

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My app has a scene with buildings, roads, airport runways, etc, and objects are clipped with reasonable near and far frustum values. But, I also want to look up, see the moon or other planets, and then travel to those objects in somewhat real-time and motion, while keeping them in view. This would require a far clip value in the billions. How might this situation be handled within OpenGL? Thanks.

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Guest Anonymous Poster
you would make a dynamic sky box/impostor that is your back ground that gets updated with the moons geometry every so often. eventually you will get close enough to render the full geometry, and it will no longer be part of your background impostor. This is basically what oblivion and other games do to render extreme distances. Also note that even if you do this, it would be smart to employ some kind of LOD algorithm so that the impostor/background updates do not take forever to render.



I would recommend a simple cut scene when you travel to the moon. Nothing is wrong with a cut scene showing you going to the moon level.

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Yeah, that journal is one great source of inspiration but at the same time can make you think sometimes that "us ordinary mortals cannot compare to Flavien's genius, so why even bother?"

There is another solution to the problem, where you basically render all far objects, then clear the depth buffer and render all near objects. This has also been suggested in the past here, and on at least one mailing list.

Oh, and you will probably need multiple origins for your coordinate system if you want to walk on the moon in steps less than 100km large :S

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The sky-box with scene cut doesn't seem very good. No wonder that response was Anonymous. I'm just kiddin'.

Your comments and links have given me some great ideas on how to handle things. I already use a non-depth-tested sky-dome for sky coloring, and fake stars for high-altitude flight. For distant objects, I will probably go with multiple renderings/z-buffers.

Physical realism is more important to me than photo realism.

I don't play many games, but one of my all time faves was MS Space Sim. I think I'm one of the 3 fans of that game. You could basically see any object in the known universe at any time. Do you know how they did it?

Thanks.

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Haven't tried MS Space Sim, but in the same vein, if you have not yet played Frontier First Encounters, you may want to do so now. Although from what I remember, Frontier's approach may in fact have been using impostors.

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