public void AddRandomBurst(Point location, int count)
{
for (int i = 0; i < count; i++)
{
Particle p = new Particle();
double radius = Radius + (_random.NextDouble() * 2.0 - 1.0) * RadiusVariation;
double lifetime = _random.NextDouble() * 3.0 + 1.0;
p.Location = location;
p.Velocity = new Vector(_random.NextDouble() * 200.0 - 100.0, _random.NextDouble() * -200 + 100.0);
p.LifeTime = _timeTracker.ElapsedTime;
p.DeathTime = _timeTracker.ElapsedTime + TimeSpan.FromSeconds(lifetime);
p.Diameter = 2.0 * radius;
Color startColor = StartColor;
Color startColorVariation = StartColorVariation;
Color endColor = EndColor;
Color endColorVariation = EndColorVariation;
Color startRandColor = Color.FromScRgb(startColorVariation.ScA * (float)(_random.NextDouble() * 2.0 - 1.0),startColorVariation.ScR * (float)(_random.NextDouble() * 2.0 - 1.0),startColorVariation.ScG * (float)(_random.NextDouble() * 2.0 - 1.0),startColorVariation.ScB * (float)(_random.NextDouble() * 2.0 - 1.0));
Color endRandColor = Color.FromScRgb(endColorVariation.ScA * (float)(_random.NextDouble() * 2.0 - 1.0), endColorVariation.ScR * (float)(_random.NextDouble() * 2.0 - 1.0), endColorVariation.ScG * (float)(_random.NextDouble() * 2.0 - 1.0), endColorVariation.ScB * (float)(_random.NextDouble() * 2.0 - 1.0));
p.StartColor = startColor + startRandColor;
p.EndColor = endColor + endRandColor;
_particles.Add(p);
}
}
private void UpdateParticles(double deltatime)
{
//drop particles from mouse position
if (_mouseDropsParticles && IsMouseOver)
{
_secondsUntilDrop -= deltatime;
if (_secondsUntilDrop < 0.0)
{
AddRandomBurst(_lastMousePosition - new Vector(Radius / 2.0, Radius / 2.0), 1);
_secondsUntilDrop = MouseDropDelay + (_random.NextDouble() * 2.0 - 1.0) * MouseDropDelayVariation;
}
}
if (_particles.Count > 0)
{
InvalidateVisual();
}
//update all particles
for (int i = 0; i < _particles.Count;)
{
//_particles[i]
Particle p = _particles[i];
if (_gravitateToMouse)
{
p.Velocity += (_lastMousePosition - p.Location) * _gravitateScale;
}
else
{
p.Velocity += _gravity;
}
p.Location += p.Velocity * deltatime;
if (_bounceOffContainer)
{
double radius = p.Diameter / 2.0;
if (p.Location.X - radius < 0.0)
{
p.Location.X = radius;
p.Velocity.X *= -0.9;
}
else if (p.Location.X > ActualWidth - radius)
{
p.Location.X = ActualWidth - radius;
p.Velocity.X *= -0.9;
}
if (p.Location.Y - radius < 0.0)
{
p.Location.Y = radius;
p.Velocity.Y *= -0.9;
}
else if (p.Location.Y > ActualHeight - radius)
{
p.Location.Y = ActualHeight - radius;
p.Velocity.Y *= -0.9;
}
}
//only increment counter for live particles
if (_timeTracker.ElapsedTime > p.DeathTime)
{
_particles.RemoveAt(i);
}
else
{
i++;
}
}
}
