Expose API for dynamic javascript control [enhancement] about virtualsky HOT 4 CLOSED

@kcgolden The basic idea of centring the map on an RA/Dec is great and something I've been wanting to exist for a while for similar reasons to yours. Unfortunately none of the current projections are set up for that; they are either longitude/latitude based or show the whole-sky with the poles fixed to the top/bottom. Many of them also take short-cuts in code/maths (for speed) on the assumption that the horizon stays attached to the bottom of the screen.

I have been working on a more general projection (gnomic tan) for this RA/Dec use-case but I've not been able to get it working correctly. I'm messing something up in my maths as I get reflections of the sky showing up at various positions on the sky.

Animating a pan is another problem. This feature would have to be limited to only work in this one projection. Should it go via the shortest path on the sky (a great circle)? That would probably involve using quaternions (I never quite got my head around them). Perhaps I should treat it like a standard telescope mount and just rotate in RA and Dec separately keeping north upwards. That will have less than ideal behaviour near the poles though.

So, in summary, I'd love to have those features but at the moment I'm a bit stuck on getting them implemented.

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@kcgolden You may like to know that I think I've sorted out the problem I was having with the gnomic tan projection. I've committed an update to Github but it isn't yet on the live site. I've got a test version at http://strudel.org.uk/virtualsky/?projection=gnomic&gradient=false&ground=false&dec=22.0145&ra=83.6330833&fov=60.

I haven't addressed your suggestion of panning yet.

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There we go. I've added a function very similar to the one you suggested. The only difference is that you specify the duration of the pan in milliseconds (x1000) as that matches with how other libraries set durations. Angles are provided in decimal degrees. So to pan to the Orion Nebula in 2 seconds use e.g.

planetarium.panTo(83.8220833,-5.3911111,2000);

from virtualsky.

That's really awesome. Thanks for doing that. I can't wait to get a chance
to implement this on my site. I'll let you know when.

On Thu, Nov 7, 2013 at 4:16 PM, Stuart [email protected] wrote:

Closed #12 #12.

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Reply to this email directly or view it on GitHubhttps://github.com//issues/12
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