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General >> Discussion >> Wishlist - Reading output files in GravSim
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Message started by Mal on 10/31/06 at 14:51:44

Title: Wishlist - Reading output files in GravSim
Post by Mal on 10/31/06 at 14:51:44

Now that I can output data to files (in the beta version), I'm finding that the actual visualisation side of GravSim is very much secondary now. To wit - I use the forms to enter the objects for the simulation, then start it running, then I turn the Plot option off so nothing gets drawn on the screen (to make it go faster), and then I just read off the output files and plot the graphs in Excel. I very rarely need to turn on the plots to see the orbits now.

But what would be kinda nice in GravSim is the ability to import the output files and show the full orbits (not the object moving in the orbits, but the full path) in a timestep. So I could take the output files, import them, and GravSim would then render the orbits according to that data with the year displayed in the corner, which then updates every couple of seconds to show the orbits in the next row of the table, and so on. Then you could actually see how the orbits evolve over the whole run instead of just seeing how it is right now.

I think that sort of thing would make the visualisation side a lot more useful.

Title: Re: Wishlist - Reading output files in GravSim
Post by Tony on 10/31/06 at 15:40:13

Basically an easier way of doing this:
http://orbitsimulator.com/gravity/5planet.GIF

Where instead of constructing an animated GIF from Screen Shots, Gravity Simulator would be creating the animation on the fly from the output file data?

Title: Re: Wishlist - Reading output files in GravSim
Post by Mal on 10/31/06 at 17:54:59

Yeah. Though I was thinking more in terms of having it also print the current year on the screen for each frame, and having a user-defined framerate so it doesn't all flash by in a second :).

Title: Re: Wishlist - Reading output files in GravSim
Post by Tony on 10/31/06 at 18:04:50

I could have done the year simply by placing the "Time and Date" window next to the orbits.

When creating animated GIFs, you can set the speed by placing delays between the frames.

This is a cumbersome way to do it, but your suggestion would require lots of coding.  I think the next thing I want to work on when I get a good block of time is a Runge-Kutta 4 algorithm.  This may allow us to perform simulations twice as fast.

But I agree, your idea is valuable.  The animated GIF hits at its full potential.  It might even be better done as a stand-alone program.

I could also make my own GIF player, giving the user some control.

Title: Re: Wishlist - Reading output files in GravSim
Post by Mal on 10/31/06 at 19:25:29

As I understand it, there's legal issues with GIF files (something to do with licensing, IIRC the people that made the format decided they wanted money from anyone who used it, which is why it's largely fallen out of favour as an image format on the net, and is way behind JPG and PNG). Might be worth looking into that if you're going to do anything with it in the program itself, to make sure you don't get into trouble.

But making animated gifs IS pretty cumbersome, and it doesn't help if you don't make screenshots while you're running th sum (plus, that just fills folders with loads of images as it's running, which isn't that great if you're also doing autosaves and output files).

I think it'd be a lot better to just be able to view the orbits within the program, never mind doing animated gifs or anything. I'd imagine that you must have most of the code already there somewhere - you just need to read the orbit parameters from the data file, plot an orbit corresponding to that, and then move on to the next one and plot that. Then again, this might be one of those things that sounds easier than it really is. ;)

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