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# Representing points projected onto a sphere in two dimensions

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2 replies to this topic

### #1carterza  Members

Posted 31 January 2013 - 03:58 PM

Hi and thank you for reading. Hopefully I'm posting this in the right forum.

I am working on a 2d space simulator and I'm trying to figure out the best way to create a realistic starscape.

The POV for the player will be from a spaceship's cockpit, very similar to the old Wing Commander games (Privateer is the one which I'm drawing most of my inspiration from).

I'm just getting started and one of the first tasks I'd like to complete is creating a realistic starfield. My plan initially was to procedurally generate stars on different layers to represent the distance of the player to the stars. This would give a field of depth but I quickly realized a flaw in my plans.

If the player pans the camera view I need the starfield to be representative of an actual celestial sphere. If the player pans left and then pans back to the right they should see the same starfield they were looking at previously. Same if they begin to move forwards and then move backwards.

I'm thinking that the best way to do this is to create an imaginary sphere if you will, and then to project points onto this sphere. At these coordinate projects I would render my sprites representing the stars.

Am I on the right track here in terms of how to accomplish this or am I way off. Could someone perhaps provide me with some reading material I could check out on any kind of formulas I could play around with to accomplish this? I'm admittedly pretty bad at math - coming from a server side web development background - so I would gladly accept any help I can get.

Thanks!

### #2Bacterius  Members

Posted 31 January 2013 - 05:59 PM

I don't understand the problem. You could render your realistic starfield texture on a 3D sphere centered on the camera, perspective transformation will take care of the rest. Or are you doing something else?

“If I understand the standard right it is legal and safe to do this but the resulting value could be anything.”

### #3carterza  Members

Posted 31 January 2013 - 09:52 PM

I don't understand the problem. You could render your realistic starfield texture on a 3D sphere centered on the camera, perspective transformation will take care of the rest. Or are you doing something else?

I don't want to render a 3d sphere... I want to procedurally generate stars but I don't want to render any 3d objects. If you look at this video - http://www.youtube.com/watch?feature=player_detailpage&v=py2OeGYhZVw#t=65s - and watch as he clicks and pans the camera around, that's the effect I want to simulate but in 2d.

What's a starting point for me to study to be able to create this kind of effect using only two dimensions?

Thanks again!

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