public static void UpdateParticle(ParticleManager <ParticleState> .Particle particle)
{
var velocity = particle.State.Velocity;
particle.Position += velocity;
particle.Orientation = velocity.ToAngle();
float speed = velocity.Length();
float alpha = Math.Min(1, Math.Min(particle.PercentLife * 2, speed * 1f));
alpha *= alpha;
particle.Color.A = (byte)(255 * alpha);
particle.Scale.X = particle.State.LengthMultiplier * Math.Min(Math.Min(1f, 0.2f * speed + 0.1f), alpha);
//particle.Scale.Y = particle.State.LengthMultiplier * Math.Min(Math.Min(1f, 0.2f * speed + 0.1f), alpha);
//when velocity ~ 0, set it to 0;
var pos = particle.Position;
int width = (int)GameRoot.ScreenSize.X;
int height = (int)GameRoot.ScreenSize.Y;
// collide with the edges of the screen
if (pos.X < 0)
{
velocity.X = Math.Abs(velocity.X);
}
else if (pos.X > width)
{
velocity.X = -Math.Abs(velocity.X);
}
if (pos.Y < 0)
{
velocity.Y = Math.Abs(velocity.Y);
}
else if (pos.Y > height)
{
velocity.Y = -Math.Abs(velocity.Y);
}
if (Math.Abs(velocity.X) + Math.Abs(velocity.Y) < 0.00000001f)
{
velocity = Vector2.Zero;
}
else if (particle.State.Type == ParticleType.Enemy)
{
velocity *= 0.94f;
}
else
{
velocity *= 0.96f + Math.Abs(velocity.X) % 0.04f;
}
if (particle.State.Type != ParticleType.IgnoreGravity)
{
foreach (var blackHole in EntityManager.BlackHoles)
{
var dPos = blackHole.Position - pos;
float distance = dPos.Length();
var n = dPos / distance;
velocity += 10000 * n / (distance * distance + 10000);
// add tangential acceleration for nearby particles
if (distance < 400)
{
velocity += 45 * new Vector2(n.Y, -n.X) / (distance + 100);
}
}
}
particle.State.Velocity = velocity;
}
public static void UpdateParticle(ParticleManager <ParticleState> .Particle particle)
{
var vel = particle.State.Velocity;
float speed = vel.Length();
// using Vector2.Add() should be slightly faster than doing "x.Position += vel;" because the Vector2s
// are passed by reference and don't need to be copied. Since we may have to update a very large
// number of particles, this method is a good candidate for optimizations.
Vector2.Add(ref particle.Position, ref vel, out particle.Position);
// fade the particle if its PercentLife or speed is low.
float alpha = Math.Min(1, Math.Min(particle.PercentLife * 2, speed * 1f));
alpha *= alpha;
particle.Tint.A = (byte)(255 * alpha);
// the length of bullet particles will be less dependent on their speed than other particles
if (particle.State.Type == ParticleType.Bullet)
{
particle.Scale.X = particle.State.LengthMultiplier * Math.Min(Math.Min(1f, 0.1f * speed + 0.1f), alpha);
}
else
{
particle.Scale.X = particle.State.LengthMultiplier * Math.Min(Math.Min(1f, 0.2f * speed + 0.1f), alpha);
}
particle.Orientation = vel.ToAngle();
var pos = particle.Position;
int width = (int)NeonShooterGame.ScreenSize.X;
int height = (int)NeonShooterGame.ScreenSize.Y;
// collide with the edges of the screen
if (pos.X < 0)
{
vel.X = Math.Abs(vel.X);
}
else if (pos.X > width)
{
vel.X = -Math.Abs(vel.X);
}
if (pos.Y < 0)
{
vel.Y = Math.Abs(vel.Y);
}
else if (pos.Y > height)
{
vel.Y = -Math.Abs(vel.Y);
}
if (particle.State.Type != ParticleType.IgnoreGravity)
{
foreach (var blackHole in EntityManager.BlackHoles)
{
var dPos = blackHole.Position - pos;
float distance = dPos.Length();
var n = dPos / distance;
vel += 10000 * n / (distance * distance + 10000);
// add tangential acceleration for nearby particles
if (distance < 400)
{
vel += 45 * new Vector2(n.Y, -n.X) / (distance + 100);
}
}
}
if (Math.Abs(vel.X) + Math.Abs(vel.Y) < 0.00000000001f) // denormalized floats cause significant performance issues
{
vel = Vector2.Zero;
}
else if (particle.State.Type == ParticleType.Enemy)
{
vel *= 0.94f;
}
else
{
vel *= 0.96f + Math.Abs(pos.X) % 0.04f; // rand.Next() isn't thread-safe, so use the position for pseudo-randomness
}
particle.State.Velocity = vel;
}