public void Update(GameTime gameTime)
{
float now = (float)gameTime.TotalGameTime.TotalMilliseconds;
for (int i = particles.Count - 1; i >= 0; i--)
{
ParticleData p = particles[i];
float time_alive = now - p.BirthTime;
if (time_alive > p.MaxAge)
{
particles.RemoveAt(i);
}
else
{
//update p
float rel_age = time_alive / p.MaxAge;
p.Position = 0.5f * p.Accelaration * rel_age * rel_age + p.Direction * rel_age + p.OriginalPosition;
float inv_age = 1.0f - rel_age;
Vector4 v = p.ModColor.ToVector4();
v.W = inv_age;
//v.Y = inv_age;
p.ModColor = new Color(v);
Vector2 pos_from_center = p.Position - p.OriginalPosition;
float distance = pos_from_center.Length();
p.Scaling = MathHelper.Clamp(inv_age - 0.4f, 0f, 1f);
particles[i] = p;
}
}
}
public void Draw(SpriteBatch batch)
{
for (int i = 0; i < particles.Count; i++)
{
ParticleData p = particles[i];
batch.Draw(Texture, p.Position, null, p.ModColor, i, origin, p.Scaling, SpriteEffects.None, 1);
}
}
public static ParticleGroup CreateGroup(Texture2D texture, int count, eParticleGroupType type, Vector2 position, float offset_radius, Color color, float size, int degrees_lowerlimit, int degrees_upperlimit, GameTime gameTime)
{
ParticleGroup group = new ParticleGroup();
group.Particle_Count = count;
group.Position = position;
group.Scaling_Mode = eParticleScalingMode.Shrinking;
group.Texture = texture;
Random randomizer = new Random();
float max_age = 2000.0f;
if (offset_radius < 1)
{
group.origin = new Vector2(texture.Width / 2, texture.Height / 2);
}
else
{
group.origin = new Vector2(offset_radius);
}
for (int i = 0; i < count; i++)
{
ParticleData particle = new ParticleData();
particle.OriginalPosition = position;
particle.BirthTime = (float)gameTime.TotalGameTime.TotalMilliseconds;
particle.MaxAge = max_age;
particle.ModColor = color;
float distance = (float)randomizer.NextDouble() * size;
Vector2 displacement = new Vector2(distance, 0);
float angle = MathHelper.ToRadians(randomizer.Next(degrees_lowerlimit, degrees_upperlimit));
displacement = Vector2.Transform(displacement, Matrix.CreateRotationZ(angle));
particle.Direction = displacement;
particle.Accelaration = 3.0f * particle.Direction;
group.particles.Add(particle);
}
return(group);
}