public void Update(GameTime gameTime)
{
float now = (float)gameTime.TotalGameTime.TotalMilliseconds;
for (int i = particleList.Count - 1; i >= 0; i--)
{
ParticleData particle = particleList[i];
float timeAlive = now - particle.BirthTime;
if (timeAlive > particle.MaxAge)
{
particleList.RemoveAt(i);
}
else
{
float relAge = timeAlive / particle.MaxAge;
particle.Position = 0.5f * particle.Accelaration * relAge * relAge + particle.Direction * relAge + particle.OrginalPosition;
float invAge = 1.0f - relAge;
particle.ModColor = new Color(new Vector4(invAge, invAge, invAge, invAge));
Vector2 positionFromCenter = particle.Position - particle.OrginalPosition;
float distance = positionFromCenter.Length();
particle.Scaling = (50.0f + distance) / 200.0f;
particleList[i] = particle;
}
}
}
public void Draw(SpriteBatch spriteBatch)
{
spriteBatch.End();
spriteBatch.Begin(SpriteSortMode.BackToFront, BlendState.Additive);
for (int i = 0; i < particleList.Count; i++)
{
ParticleData particle = particleList[i];
spriteBatch.Draw(explosionTexture, particle.Position, null, particle.ModColor, i, new Vector2(256, 256), particle.Scaling, SpriteEffects.None, 1);
}
spriteBatch.End();
spriteBatch.Begin();
}
private void AddExplosionParticle(Vector2 explosionPos, float explosionSize, float maxAge, GameTime gameTime)
{
ParticleData particle = new ParticleData();
particle.OrginalPosition = explosionPos;
particle.Position = particle.OrginalPosition;
particle.BirthTime = (float)gameTime.TotalGameTime.TotalMilliseconds;
particle.MaxAge = maxAge;
particle.Scaling = 0.25f;
particle.ModColor = Color.White;
float particleDistance = (float)randomizer.NextDouble() * explosionSize;
Vector2 displacement = new Vector2(particleDistance, 0);
float angle = MathHelper.ToRadians(randomizer.Next(360));
displacement = Vector2.Transform(displacement, Matrix.CreateRotationZ(angle));
particle.Direction = displacement * 2.0f;
particle.Accelaration = -particle.Direction;
particleList.Add(particle);
}