Simple 2D black hole simulator

[Fizyk]

I made a simple 2-dimensional simulator of a spaceship flying near a black hole and I thought I'd share it

EDIT: I made a new version, more detailed description can be found on page 2 of this thread.

You can see the [ame="http://en.wikipedia.org/wiki/Apsidal_precession"]apsidal precession[/ame] in the picture

Forgive the poor graphics (if we can even call it graphics ), but it was just an attempt to simulate black hole physics. I'm going to improve it a bit in the near future.

You can download it here: http://dl.dropbox.com/u/7065759/Black Hole/Black_hole_old.exe

You have a spaceship orbiting a black hole at about 5 Schwarzschild radii from the center. Controls:

W/S/A/D - single press increases forward/backward/left/right thrust.
Q - thrust cutoff.

There are a few fun things to try:

1. Dropping into the black hole. You can see how the board time slows down. Also, there is one quite surprising effect, see if you can spot it and explain it
2. Lowering the orbit. This is damn hard, I still can't succeed - mostly it's poor controls, but this is the only way I could get it to work; I'll need to modify the program to make it better.
3. "Slingshot" around the black hole - now this is funny, because if you aim right, you can make a full circle and get launched again in the same direction (actual circle is very hard, I had managed to get a trajectory that intersected itself though). This is quite different to Newtonian mechanics, where you always get a hyperbola.

Hope you like it

 

[Wishbone]

My antivirus says that a Keylogger has been detected.

 

[Fizyk]

What.

That's strange, I assure you I have put no keylogger in there. Maybe that's because I use the GetAsyncKeyState functions for the controls.

In case you want proof (I know I'm not a recognized member and I guess you may not want to just take my word), I can post whole source of this program.

 

[Urwumpe]

My antivirus says that a Keylogger has been detected.

Can't confirm it here, my A/V doesn't detect anything and manually checking the file imports verifies that it does not import any windows function, that it does not need.

 

[Wishbone]

hehe, you're recognized, and most likely related to Kandinsky...

Now back to the functions: I did have a look at the file (see, your name is in there ), encountered no suspicious kernel-level calls, and noticed that the "keylogger" alarm goes on if the window loses focus. Suggest you should compile with Release setting and post the exe for us to verify that the alert was debug-related.

 

[Keatah]

I ran it by VirusTotal (www.virustotal.com) and they couldn't find anything. 43 scanners said ok, and that's good enough for me.

 

[Fizyk]

Now back to the functions: I did have a look at the file (see, your name is in there )

Haha, indeed, I wasn't aware things like that remain in the exe files

Suggest you should compile with Release setting and post the exe for us to verify that the alert was debug-related.

Umm, this is the release version - actually, in the same place where my name is you can see that the directory was ".../Release/..." .

 

[Wishbone]

slight paranoia... quite possible that it is the result of an earlier exam re-sit today, which the student failed

Back to relativity: is there any way to show thrust graphically in the right panel (e.g., with an arrow)? I've managed to get nice spirals around the hole so far.

 

[orb]

Haha, indeed, I wasn't aware things like that remain in the exe files


Umm, this is the release version - actually, in the same place where my name is you can see that the directory was ".../Release/..." .

For the Release configuration, in the "Project Properties -> Configuration Properties", for "C/C++ -> General -> Debug Information Format" select "Disabled", and for "Linker -> Debugging -> Generate Debug Info" select "No". This will disable generation and exclude the PDB file referencing from the EXE file.

 

[Fizyk]

For the Release configuration, in the "Project Properties -> Configuration Properties", for "C/C++ -> General -> Debug Information Format" select "Disabled", and for "Linker -> Debugging -> Generate Debug Info" select "No". This will disable generation and exclude the PDB file referencing from the EXE file.

I tried it, but for some reason the compiler still generates debug database and adds the reference to the .exe file. That doesn't bother me much, though

Also, I uploaded a new version of the program, which displays one more information, namely what I called "total proper velocity". Total velocity, displayed before, is total velocity as seen by the observer at infinity and doesn't take different time flow where the ship is into account. Total proper velocity takes that into account, so its value can be quite different from the non-proper total velocity.

Back to relativity: is there any way to show thrust graphically in the right panel (e.g., with an arrow)? I've managed to get nice spirals around the hole so far.

Yeah, that's possible, I'll add it in the version with new interface (which, unfortunately, might not be soon, because I have some work to do, but I'll get to it ).

 

[orb]

I tried it, but for some reason the compiler still generates debug database and adds the reference to the .exe file. That doesn't bother me much, though

This is strange, because I just tested this setting in a simple EXE file that does nothing, and the PDB wasn't referenced any longer in Release with those options. Maybe try rebuilding the whole project instead of simply building only changed files (?).

 

[Fizyk]

I realized I missed the point about turning off debugging in the linker options too - my bad. It's ok now. Thanks!
I uploaded this new version, it's available under the same address.

 

[Wishbone]

Thanks, looks fine. Yet after time (inertial) crosses 150, the black hole is no longer black but white with a thin black rim And a serious question: does the black hole rotate?

 

[Fizyk]

Yet after time (inertial) crosses 150, the black hole is no longer black but white with a thin black rim

I knew there were issues with graphics after when the window was hidden behind another window, but I never noticed it was tied to time in any way. Well, I'll rewrite the whole visual side using Qt anyway

EDIT: Indeed, it went white after about 157 seconds for me. Strange.

And a serious question: does the black hole rotate?

Nope, it's the Schwarzschild black hole, but I was trying to write the code in a way that will allow relatively easy switch to Kerr if I ever feel like it

 

[Stevodoran]

This is good fun. Thanks.

 

[Linguofreak]

By "board time" I take it you mean "on-board time"?

Would it make the math (or the programming) too much hairier to give an option to propagate the trajectory by on-board time rather than time-at-infinity?

 

[Fizyk]

By "board time" I take it you mean "on-board time"?

Would it make the math (or the programming) too much hairier to give an option to propagate the trajectory by on-board time rather than time-at-infinity?

Yeah, that's what I meant.

The math would only differ by one division I just chose the time at infinity due to a bit external look of this simulator. If I ever take it into 3D (which I'm planning to do, but it may be too much for me) and first-person-perspective, the on-board time will be the obvious choice as the main time.

I'll make the version using on-board time in a moment.

EDIT: Here you are:
http://dl.dropbox.com/u/7065759/Black_hole_onboard.exe

It goes a bit crazy when you fall on the horizon, because from the on-board perspective you should pass it and fall to the singularity, but I don't simulate the inside of the black hole. Also it's quite easy to see how interstellar travel can be possible even without FTL

 

[Stevodoran]

A little problem. After an extensive period of time the ship dissapears and their are two black holes both white:

Notice it tipped off my antivirus but its clean.

Other than that its great fun and you can make cool orbits

Just one request's: Can you make the controls a little less responsive?

 

[Fizyk]

A little problem. After an extensive period of time the ship dissapears and their are two black holes both white:

Yeah, I don't know why that happens, but I'm currently rewriting this using Qt, so it should work better when I finish.

Other than that its great fun and you can make cool orbits

Glad to hear that

Just one request's: Can you make the controls a little less responsive?

I'll make them more convenient in the Qt version

 

[Stevodoran]

Yeah, I don't know why that happens, but I'm currently rewriting this using Qt, so it should work better when I finish.


Glad to hear that


I'll make them more convenient in the Qt version

Whats Qt?