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silverRohan

Planets

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One of the things I've been wanting to do is render a planet, like the Earth. Rendering a sphere is not exactly hard, but getting a good texture on it, and including things like bump mapping, selectable features, etc. is going to be the more challenging part. Anyone done something like this before or know where I could find some more information on rendering realistic looking planets?

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when doing the selection part you could always fake the audience by drawing your own selections....how realistic do you want your scene. There are many tricks that can be applied to a model. You use a modeling program if you wish but if you don't want to i think your answer hangs around with alot of math

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If you want bump mapping or a well-applied texture and what not,
a modelling package isn't an option. it's a must.
Bump mapping for spheres would be best done with shaders. Selecting
is done with D3DXProject, iirc. It turns a screen coordinate into
a 3D world coordinate, given a depth value. Then you do ray collision
to see if your planet got selected.
Hope that helps.

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A modeling package isn't a must at all. For planets, procedural generation is very common. See Texturing & Modeling: A Procedural Approach or Mojoworld for details about Ken Musgrave's implementations. Sean O'Neill created an OpenGL based procedural planet viewer, which is quite nice, and he even wrote a Gamasutra article detailing it. Of course, if you choose to go the procedural route, be aware that you may never actually get around to being 'finished,' since you'll always find more cool stuff you want to add :-)

-bodisiw

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Hey, bodisiw. =)
Just wondering. How would you texture a sphere with correct UVs and all
without a modelling package or texturing program of some sort?
For creating the model, and for materials, sure you don't need one,
but how would you texture it? Just curious, thanks. =)

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I'd recommend the book "Texturing and Modeling - A procedural approach, 3rd edition" if you're into the procedural generation of planet textures. Alternatively you can use already existing textures, like the Nasa's Blue Marble dataset (Earth in 46000x24000 textures). The procedural generation is better if you want to have a lot of planets with different looks. Here is an Earth-like one i recently generated using multifractal noise (and lots of tweaking). It's 1/6th of the full texture since it's mapped onto a cube deformed into a sphere:


Click here for the large version (2048x2048).

Y.

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