Overview
GravitySimulator (as the name suggests) is a real-time gravity simulation screensaver. There are several models available which can be manually selected or cycled through on a periodic basis (default) these range from stable star systems to black holes.

Feedback
Please note that the current release is the initial Beta so any comments, complaints, suggestions, would be greatly appreciated. If your suggestion is good and it gets into the next release I'll credit the provider.

Cost
GravitySimulator is FREEWARE i.e. it's FREE i.e. Don't pay for it!. If you like it and feel generous enough to make a donation to the project then 50% will go to charity (See Here).

Spyware/Shareware
There is absolutely no shareware/spyware bundled with this screensaver whatsoever. The screensaver does check periodically with the GravitySimulator web server for upgrade notices (which appear at the bottom right corner of the screen when the screen saver starts) and as part of this it does report the following information: Hours of usage, Number of display adapters, Number of CPU cores and Number of objects. None of this information is used for marketing purposes (and I'd be impressed if such a use could be found for it!).

Background
GravitySimulator was written as a training exercise in the .NET Framework and includes in its core technology VB.Net, C#.Net, c++.Net, x86 Assembly and SSE2/SSE3 code.
The simulator is extremely CPU intensive and will optimise itself to the speed of your system (i.e. the more CPU / Graphics power available the more objects are created. The main test system runs with a 3GHZ Quad Core Intel Core 2 Processor and two dual-head Nvidia 8600GTS adapters (4 Displays) which allows for approximately 5000 objects. Note, to double the amount of objects you need to quadruple the processing power! The reason for this is that for each frame the interaction of every object against every other object needs to be calculated.
Additionally if your CPU supports SSE2/SSE3 (All new CPU's do) then the maths core is run using these instructions which gives a four to eight times increase in processing power.
The screensaver will run on all the display adapters on the system and will select a different camera angle for each display by default. Note that manual selection of a camera view will apply that view to all displays.

System Requirements:

Installation
Download the exe file from Here and complete the installation as directed. The installer may require you to install the '.NET Framework 3.5' and also the 'DirextX9 for Managed Code' runtimes and you may also be asked to reboot your system.
Once installation is complete the Windows screen saver 'Display Properties' dialog box should appear and you can select 'Gravity' from the list. The only option available is to select the model that is displayed.

Screen saver options (when the screen saver is running):
P - Status Info
Toggles the status information on/off in the bottom right corner of the display.

N - Automatic Model
This will set the screensaver to change the model automatically on a periodic basis. Some of the models will run for different periods of time.

M - Change Model
Manually selects the next model and also turns off automatic model selection. To return to automatic selection press 'N'.

PgUp - x2 Objects
Doubles the amount of objects in the model (and also restarts the model).The system will auto adjust this value if there are to many objects.

PgDn - /2 Objects
Halves the amount of objects in the model (and also restarts the model).The system will auto adjust this value if there are to few objects.

C - Change Camera
Selects the next camera and disables the automatic camera mode. If your system has more than one display then every display will show the same view.

A - Automatic Camera
This set the automatic camera mode and the cameras will be changed periodically. If your system has more than one dislpay then each display will show a different view.

R - Reset Model
Restarts the current model.

G - Toggle Gravity Mode
Toggles the gravity mode between Real & High. This is normally handled automatically and is set depending on the type of model you are viewing. Changing the setting manually will cause catastrophic effects (but it can be quite spectacular!).

D - Make a Donation
Takes you to the Donation page on the GravitySimulator website (See Here).

V - Toggle Model Info
Toggles the model name information on/off in the top left corner of the screen.

P - Toggle Status Info
Toggles the display of the shortcut keys in the bottom left of the screen.

S - Toggle stats Info
Toggles the Stats information on/off in the top right corner of the screen. This gives information on the current status of the screensaver such as number of objects/displays/CPU cores, Processor usage etc. (Mainly nerdy stuff).