public void ShouldNotMoveWhenNoVelocity()
{
var particle = new Particle(Vector2D.Zero);
particle.Move(TimeSpan.FromSeconds(1));
Assert.That(particle.Position, Is.EqualTo(Vector2D.Zero));
}
public Vector2D GetAcceleration(Particle particle)
{
var distance = GetDistance(particle);
if (distance < 1)
distance = 1;
return Force/distance;
}
public void ShouldBump(double startVelocityX, double startVelocityY, double collisionPlaneX, double collistionPlaneY, double resultVelocityX, double resultVelocityY)
{
// given
var particle = new Particle(Vector2D.Zero, new Vector2D(startVelocityX, startVelocityY));
var collisionNormalPlane = new Vector2D(collisionPlaneX, collistionPlaneY);
// when
particle.Bump(collisionNormalPlane);
// then
Assert.That((particle.Velocity - new Vector2D(resultVelocityX, resultVelocityY)).GetLength() < 0.00000001);
}
public void ShouldMoveWithConstantSpeedWhenNoAcceleration()
{
var particle = new Particle(Vector2D.Zero, new Vector2D(1, 0));
particle.Move(TimeSpan.FromSeconds(1));
Assert.That(particle.Position, Is.EqualTo(new Vector2D(1, 0)));
Assert.That(particle.Velocity, Is.EqualTo(new Vector2D(1, 0)));
particle.Move(TimeSpan.FromSeconds(1));
Assert.That(particle.Position, Is.EqualTo(new Vector2D(2, 0)));
Assert.That(particle.Velocity, Is.EqualTo(new Vector2D(1, 0)));
}
public void ShouldAccelerate()
{
var particle = new Particle(Vector2D.Zero, Vector2D.Zero, new Vector2D(1, 0));
particle.Move(TimeSpan.FromSeconds(1));
Assert.That(particle.Position, Is.EqualTo(new Vector2D(1, 0)));
Assert.That(particle.Velocity, Is.EqualTo(new Vector2D(1, 0)));
particle.Move(TimeSpan.FromSeconds(1));
Assert.That(particle.Position, Is.EqualTo(new Vector2D(3, 0)));
Assert.That(particle.Velocity, Is.EqualTo(new Vector2D(2, 0)));
}
private double GetDistance(Particle particle)
{
var p = particle.Position;
var squaredLength = (End - Start).GetSquaredLength();
var lengthToA = (p - Start).GetSquaredLength();
var lengthToB = (p - End).GetSquaredLength();
if (lengthToA > squaredLength || lengthToB > squaredLength)
return Math.Min(lengthToA, lengthToB);
var a = Start;
var n = (End - Start).Normalize();
var distance = ((a - p) - n * ((a - p).Dot(n))).GetLength();
return distance;
}
private void UpdatePosition(Shape ellipse, Particle particle)
{
if (particle.IsStopped())
ellipse.Fill = _cholesterolBrush;
ellipse.SetValue(Canvas.LeftProperty, particle.Position.X - _particleSize /2);
ellipse.SetValue(Canvas.TopProperty, particle.Position.Y - _particleSize / 2);
}
void dispatcherTimer_Tick(object sender, EventArgs e)
{
_dispatcherTimer.Stop();
_world.Move(TimeSpan.FromMilliseconds(5));
var toRemove = new Collection<Model.Particle>();
// find all particles that need to be removed
foreach (var particle in _world.Particles)
{
if (particle.Position.X > canvas.ActualWidth || particle.Position.X < 0 || particle.Position.Y > canvas.ActualHeight || particle.Position.Y < 0)
toRemove.Add(particle);
}
foreach (var particle in toRemove)
{
_world.RemoveParticle(particle);
canvas.Children.Remove(_visualizationMap[particle]);
_visualizationMap.Remove(particle);
}
// generate new particles
if ((DateTime.Now - _lastGenerated) > TimeSpan.FromMilliseconds(10))
{
int count = _randomGenerator.Next(2, 5);
for (int i = 0; i < count; i++)
{
var sx = _randomGenerator.Next(200, 390);
var sy = 300;
var vx = 0;
var vy = _randomGenerator.Next(-150, -75);
var particle = new Particle(new Vector2D(sx, sy), new Vector2D(vx, vy));
_world.AddParticle(particle);
var ellipse = CreateParticleVisualisation(particle);
_visualizationMap.Add(particle, ellipse);
}
_lastGenerated = DateTime.Now;
}
// find all particles that needs to be added
foreach (var particle in _world.Particles.Where(p => !_visualizationMap.ContainsKey(p)).ToArray())
{
var ellipse = CreateParticleVisualisation(particle);
_visualizationMap.Add(particle, ellipse);
}
// update position of each particle visualisation
foreach (var particle in _world.Particles)
{
UpdatePosition(_visualizationMap[particle], particle);
}
_dispatcherTimer.Start();
}
private Ellipse CreateParticleVisualisation(Particle particle)
{
var ellipse = new Ellipse();
ellipse.Fill = _bloodBrush;
ellipse.Width = _particleSize;
ellipse.Height = _particleSize;
UpdatePosition(ellipse, particle);
canvas.Children.Add(ellipse);
return ellipse;
}
public void RemoveParticle(Particle particle)
{
Particles.Remove(particle);
}
public void AddParticle(Particle particle)
{
Particles.Add(particle);
}
public bool IsInRange(Particle particle)
{
var distance = GetDistance(particle);
return distance < Range;
}