Post #6by VikingTechJPL » 24.04.2010, 03:38
Tim,
Here's a "quick and dirty" method that may help get you started or at least give you some other ideas.
The photon torpedo (smaller star) is actually a star circling a barycenter, so it actually moves between the 2 ships (the larger stars) only once each orbit in CELESTIA. Still, if you save (as cel:urls) its motion between the stars several different times (and from several different angles), you can call them sequentially from your script and produce the effect of many torpedo shots.
Basically, in an stc file, I've created two fixed stars that are near each other and 500 light years from Earth. You'll see their coordinates in the stc files. You would substitute your ships in these locations. Then I created a star moving around a barycenter located at the Earth and in the same plane and at the same distance as the two fixed stars. So on Jan 1, 2000 the small star starts moving from FixedStar1 to FixedStar2 because everything in CELESTIA is geared to the J2000 epoch. As I said, you can change your camera to look at this from any angle and any distance. Because the radius of the small star's (photon torpedo's) orbit is so large, it looks like it's moving in a straight line.
If you're making a movie instead of a script, you can record many little clips from a bunch of different angles and then stitch them together. If you want FixedStar2 to return fire, just run time backwards after the small star has reached it. The demo AVI video shows the photon torpedo (smaller star) bouncing back and forth because I just kept reversing time. The included AVI's very rough, only meant to show that motion is possible.
You'll need to make sure that all of your distances and sizes are consistent, because the units for stars and satellites are not expressed the same in CELESTIA (assuming, that is, that your models are satellite objects). CELESTIA's source code has all of the constants and multiples you'll need.
Not knowing what version of CELESTIA you're using, I've included an stc for both for 1.4.1 and 1.6.0. Each also contains a "commented out" cel:url that you can put in a word processor and use after you're installed the stc files in your extras folder and restarted CELESTIA.
Let me know how it works out. I hope it helps.
Gary
1.6.1, Dell Studio XPS, AMD 2.7 GHz, 8 GB RAM, Win 7 64-bit, ATI Radeon HD 5670
1.6.0, Dell Inspiron 1720, Intel Core Duo 2 Ghz, 3 GB RAM, Win Vista, NVIDIA GeForce 8600M G/GT
1.4.1, Dell Dimension 4700, Pent-4 2.8 GHz, 512 MB RAM, Win XP SP2, Radeon X300
