public static void SequentialDraw(Body[] bodies, Graphics g, float planetRadius)
{
for (int i = 0; i < bodies.Length; i++)
{
bodies[i].Paint(g, planetRadius);
}
}
static void Main()
{
// We simulate some of the planets in our solar system
Body[] bodies = new Body[]{
new Body(1.496e11, 0, 0, 2.980e04, 5.974e24,Color.Blue), // Earth
new Body(2.279e11, 0, 0, 2.410e04, 6.419e23,Color.Red), // Mars
new Body(5.790e10, 0, 0, 4.790e04, 3.302e23, Color.Gray), // Mercury
new Body(1.082e11, 0, 0, 3.500e04, 4.869e24, Color.Yellow), // Venus
new Body(0, 0, 0, 0, 1.989e30, Color.Orange) // Sun
};
// Comment out the section below to generate
// some random bodies instead of the solar system.
/*
int N = 1000;
Body[] bodies = NBodySolver.GenerateRandomBodies(N); */
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new NBodyForm(new NbodyPanel(800, 800, -2.5e11f, 2.5e11f, -2.5e11f, 2.5e11f, 100000, bodies, true)));
// Comment out the line below to run a console based version
// of the N-body problem. Remember to change the "Output type"
// of the project to "Console application"
// NBodyConsole();
}
public NbodyPanel(
int width, // width of the panel
int height, // height of the panel
float xMin, // the smallest visible x-coordinate
float xMax, // the largest visible x-coordinate
float yMin, // the smallest visible y-coordinate
float yMax, // the largest visible y-coordinate
float dt, // the time step-size
Body[] bodies, // the bodies to be shown
bool parallel // should the calculations be done in parallel
)
{
this.Size = new Size(width, height);
this.DoubleBuffered = true;
this.BackColor = Color.Black;
float xScale = (float)(width / (xMax - xMin));
float yScale = (float)(height / (yMax - yMin));
float xTranslate = (float)Math.Abs(xMin * xScale);
float yTranslate = (float)Math.Abs(yMin * yScale);
float planetRadius = ((xMax - xMin) / width) * 10;
Timer timer = new Timer();
timer.Interval = 1;
timer.Tick += delegate(Object sender, EventArgs e)
{
Bitmap bmpNew = new Bitmap(width, height);
Graphics g = Graphics.FromImage(bmpNew);
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
g.Transform = new System.Drawing.Drawing2D.Matrix(xScale, 0, 0, yScale, xTranslate, yTranslate);
if (parallel)
{
NBodySolver.ParallelCalcForceAndUpdate(bodies, dt);
}
else
{
NBodySolver.SequentialCalcForceAndUpdate(bodies, dt);
}
NBodySolver.SequentialDraw(bodies, g, planetRadius);
this.bmp = bmpNew;
Refresh();
};
timer.Start();
}
/****************************
* Calculate the effect of
* the Body b. This Body won't
* be moved until the update
* method is called.
****************************/
public void CalcForce(Body b)
{
double dx = b.x - x;
double dy = b.y - y;
double r = Math.Sqrt(dx * dx + dy * dy);
double F = (G * mass * b.mass) / (r * r + EPS * EPS);
xForce += F * dx / r;
yForce += F * dy / r;
}
/************************ Sequential methods ****************************/
public static void SequentialCalcForceAndUpdate(Body[] bodies, double dt)
{
for (int i = 0; i < bodies.Length; i++)
{
bodies[i].Reset();
for (int j = 0; j < bodies.Length; j++)
if (i != j)
bodies[i].CalcForce(bodies[j]);
}
for (int i = 0; i < bodies.Length; i++)
{
bodies[i].Update(dt);
}
}
/************************ Parallel methods ****************************/
public static void ParallelCalcForceAndUpdate(Body[] bodies, double dt)
{
Parallel.For(0, bodies.Length, 100, delegate(int i)
{
bodies[i].Reset();
for (int j = 0; j < bodies.Length; j++)
if (i != j)
bodies[i].CalcForce(bodies[j]);
});
Parallel.For(0, bodies.Length, 100, delegate(int i)
{
bodies[i].Update(dt);
});
}
public static Body[] GenerateRandomBodies(int N)
{
Random rand = new Random();
Body[] bodies = new Body[N];
// Generate some random bodies:
for (int i = 0; i < N - 1; i++)
{
bodies[i] = new Body(RandomDouble(rand, 2.5E11),
RandomDouble(rand, 2.5E11),
RandomDouble(rand, 4e4),
RandomDouble(rand, 4e4),
RandomDouble(rand, 1E25), Color.Green);
}
// And one in the middle, that is much heavier than the rest
bodies[N - 1] = new Body(0, 0, 0, 0, 1.989e30, Color.Orange);
return bodies;
}
