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new beta version (Read 56880 times)
EDG
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Re: new beta version
Reply #45 - 06/18/11 at 22:11:50
 
Quote from Tony on 06/11/11 at 10:53:19:
Thanks for the report.
You'll probably find that there is a problem with onlyplanets.gsim even if you don't add more items.  There are some problems opening simulations created with previous versions that are saved with time steps other than 1 second in the new beta.  This might sound like a pain to try, but open onlyplanets in an older beta (prior to May 2011), reduce the time step to 1, resave it.  Then it should open fine in the new beta and you can create your additional objects and it should work fine.  I'll correct this soon so you can open older simulations with the Beta, but for the time being, you can only open existing sims saved at timestep = 1.

 
Has this been fixed yet? Is there a way to manually edit existing sims (say, in notepad) to edit the timestep to equal 1?
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Re: new beta version
Reply #46 - 06/18/11 at 22:17:57
 
It hasn't been fixed yet.  You could edit the .gsim in notepad by dividing all the velocities by the time step, and dividing all the masses by timestep^2.  But it's much easier to simply keep an older version of the beta on your system, and use it to open the file, reduce the timestep to 1, then resave the file.
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Re: new beta version
Reply #47 - 10/18/11 at 17:59:24
 
This installs a new version.  It contains dlls for RK4, and variable-step RK4.  Give it a try and let me know if it installs smoothly.
http://orbitsimulator.com/gravity/beta/setupGravitySimulatorAlpha3.exe
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Re: new beta version
Reply #48 - 10/20/11 at 14:51:19
 
Is there a changelog anywhere that shows what's been fixed/updated/removed in the various alpha and beta releases? (eg does this new alpha fix the timestep issue described above?)
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Re: new beta version
Reply #49 - 10/20/11 at 16:33:26
 
I think I fixed that one.  You can double check.  The new version lets you choose an integrator from a dropdown list.  It gives you dlls for the RK4 routines.  It has a variable time step routine, so you can run simulations at fast speed and they automatically slow down for close approaches.
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Re: new beta version
Reply #50 - 12/30/12 at 12:23:38
 
Quote from EDG on 10/20/11 at 14:51:19:
Is there a changelog anywhere that shows what's been fixed/updated/removed in the various alpha and beta releases? (eg does this new alpha fix the timestep issue described above?)

 
I'm still hoping a changelog exists and can be posted (surely Tony must make one whenever he updates the beta?!) - I've quite lost track of what is now possible in the program.  
 
Is the install file downloadable from the website going to be updated to the latest beta too? I think it's still the original basic version.
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Re: new beta version
Reply #51 - 03/13/13 at 20:29:11
 
There are other integrators in the "new" GravSim3Alpha... I presume that Euler is the 'original' integrator, and you mention RK and RK4 above, but what should "Leapfrog" and "Verlet" be used for?
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Re: new beta version
Reply #52 - 03/14/13 at 00:52:55
 
The leapfrog and verlet are there for comparison.  RK4 is the best one to use.  Try creating a new simulation, then put 1 object in orbit above the Sun, just above its surface.  Open a distance and velocity box from the view menu.  Notice that in Euler, the distance varies slightly over the orbit, but it holds steady in RK4.
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Re: new beta version
Reply #53 - 04/16/13 at 21:09:05
 
It seems that the 'help' functions in the help menu aren't working in the 3.0 alpha either. Whether I go to Gravity Simulator Help or to the Gravity Simulator Online help, the program crashes whenever it tries to open Internet Explorer (I have IE 9 on my system). Though can we set a Preference to point it to a preferred browser? While I have IE9 on my computer, I don't use it - I use Firefox instead.  
 
(I think this is where it's supposed to be pointing to: http://orbitsimulator.com/gravity/tutorials/tutorials.html - this explains all the items in the (non-alpha?) menus at least).
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Re: new beta version
Reply #54 - 07/25/13 at 15:54:04
 
http://orbitsimulator.com/gravity/beta/csv.csv
http://orbitsimulator.com/gravity/beta/GravitySimulatorAlpha2013July24_3.0.exe
 
Here is the latest beta with Mal's spreadsheet suggestion.  There's a very good chance you'll find bugs in this, but it works with the attached csv.  Try it out and report any bugs to me.
 
Instructions for importing objects from spreadsheet.
 
1. Pause simulation
2. Delete all existing objects using Objects > Delete Objects menu. (see note below)
3. Open "Create Objects" dialog box.
4. Press Import button.
5. Navigate to your csv file.
 
note: If you are importing objects onto an existing system, you do not need to delete the existing objects, but every object in your spreadsheet needs to have a ref obj.  In the attached csv file, Ixtab has no reference object, so this spreadsheet needs to be imported into a system with no existing members.
 
CSV file:
Follow the format of the attached csv file exactly.
Format all your spreadsheet cells as text, and save it as a csv file.
In Ref Obj, if you add 'b' to the reference object name, it is the same as choosing the barycenter option on the Create Objects interface. You must put single quotes around the b so gravity simulator doesn't consider the b to be part of the name.
Mass: Add S for sun, E for Earth, J for Jupiter, kg for kilograms.  If you put nothing, default is Earth mass.
Color: At the moment, the only options are red, black, green, yellow, blue, magenta, cyan, white.  If you want more colors, tell me the hexidecimal color code and name for each additional color.
SMA: Add  m, km, AU, LY for units
 
Distribution:
Use a dash for a range.  For example if you create 3 objects (first column) and put 1-3 AU, you will get an object at 1, 2, and 3 AU
Use ~ for +/- percent.
Use @ for standard deviation
 
The attached csv file will create a system centered around Ixtab.  
Akabna has definite values for all its parameters.  
Balamna will have an inclination of 2 degrees +/- 100 % (i.e. a random value between 0 and 4 degrees)
Balamna's LAN, Per, and MA will be 180 +/- 100% (i.e. a random value between 0 and 360 degrees)
The asteroids' eccentricity will be chosen by a random gaussian distribution centered on 0.1 with a standard deviation of 0.01.  Be careful. This can generate negative numbers which might crash the simulation.
The Kuipers will have a size of 10 km +/- 50% (i.e. a random number between 5 and 15 km)
The Kuipers eccentricities will have a linear distribution from 0 to 0.1 (i.e. 0, 0.05, 0.1)
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stargate38
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Re: new beta version
Reply #55 - 12/23/13 at 16:01:03
 
Why does the About box say this? GravSim is freeware:
 
Code:
Warning: ...Please do not make duplicate copies. All
new users should download and register their
shareware copy of this program from
www.gravitysimulator.com 


 
Please replace the word "Shareware" with "Freeware" in the next version
 
Also, here's a sim that I found where you can change the exponent: http://www.testtubegames.com/gravity.html
 
Can you PLEASE integrate a law-changing function into GravSim? It would help me with formation scenarios because, on top of what I haven't uploaded, I really want to see what would result from a ring of particles in "F=G*m1*m2*f(r)" gravity, where "f" is an arbitrary function (like r^-2+r^-4, which is close to relativistic gravity, or r^-2+0.1, which I call "Gravity with a set minimum"). I hope you integrate this someday; it would help with dark-matter related sims, like galaxies (where MOND is assumed).
 
Advantages for such a feature:
 
1. r^0 is easier to simulate because it changes the force law to "F=G*m1*m2", relieving stress on the CPU.
2. no object could escape from "G*m1*m2*(r^-2+r^1)" gravity.
3. Users could potentially make a sim for 2-D Space, where gravity decreases as r^-1 instead of r^-2. Circular orbital velocity/(Total mass^2)=constant
4. r^1 gravity has 2 advantages:
   a. All objects in a system will have the same orbital period
   b. Orbits are much more stable.
5. Relativity could be simulated by an "r^-2+r^-4" law.
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