Skybox vs skysphere in a space sim?
Posted 13 January 2007 - 09:10 PM
Also, I note that EVE online and other games sometimes implement "space dust" as one moves to create an illusion of movement. How is this sort of thing done? A particle effect around the ship?
Posted 13 January 2007 - 09:27 PM
I'd guess you're right about the particle effect around the ship.
You could probably get away with static particles places randomly round your environment.
I did the same thing for rain, its like the rain cloud is following you round!
Posted 13 January 2007 - 11:41 PM
Posted 14 January 2007 - 12:54 AM
I imagine the size of such a scene is limited by stretching of the texture, not to mention memory. I'm using 3Ds Max to make my scene, and I'm trying to figure out how much of a solar system I can depict in one scene.
Posted 14 January 2007 - 01:26 AM
I would draw it first with Z off so that it gets drawn over by anything else, no matter how far away it is.
Here's a article I found http://gpwiki.org/index.php/Sky_Box although its OpenGL not XNA
The texture really needs to be quite big, probably a similar size to your screen res.
Posted 14 January 2007 - 08:52 AM
If you're only talking about the amount of polygons rendered, the cost of the sky sphere is neglible compared to the sky box. I'd wager that a couple thousand polygons here or there won't make much of a difference.
Posted 14 January 2007 - 12:55 PM
Who wrote that?
Posted 14 January 2007 - 03:30 PM
Posted 14 January 2007 - 04:38 PM
Posted 15 January 2007 - 02:32 AM
Looking at Celestia's files, I see just a couple of dozen models of significant objects -- mostly regular things like asteroids, Mir and Hubbell. So they probably just have one or two spheroid models for planets and suns, and textures to put on them. I can certainly handle just making a couple dozen models for a space scene, and I can handle making textures. But how to render all the tiny points of light you see until you get close to them?
Posted 15 January 2007 - 11:57 AM
Posted 15 January 2007 - 04:19 PM
Posted 15 January 2007 - 04:56 PM
I was under the impression that skybox and sky sphere (I'll use the term "sky dome" in this post) are two different technologies.
A sky dome is actual geometry that surrounds a level. Therefore, you either end up with a lot of polygons in your sphere or really large geometry that shows seams, especially if you use a cube.
A skybox is when you have a separate area in a map--like a little room--with only a camera and the sky elements in it. When the player's camera rotates, so too does the camera in the skybox. The view in the skybox is composited with the view from the level--just added into the background. That way the player will never bump up against the geometry that makes up the sky dome, only against the geometry of the level--because there IS no geometry making up the sky, only a masked-in image that's been rendered somewhere else.
That's lifted pretty much verbatim from Luke Ahearn's book 3D GAME TEXTURES.
IMO, you'll get a much better effect--especially for your space sim which requires lots and lots of, well, space--if you use the skybox technique I mentioned here, and not a sky dome or sky sphere.
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