public ParticleEngine(Vector2 position, Vector2 scale, Color tint, int particlesPerSpawn, TimeSpan particleLifeTime, TimeSpan spawnRate, params Texture2D[] particleImages)
{
_position = position;
_particles = new List<Particle> ();
_particleImages = particleImages;
_lifeTime = particleLifeTime;
_scale = scale;
_random = new Random();
_autoSpawn = true;
_spawnCount = particlesPerSpawn;
_spawnRate = spawnRate;
_speed = 3;
_useGravity = false;
_gravityScale = 1;
_particleTint = tint;
_targetAlpha = tint.A;
_scale = scale;
_targetScale = scale;
_autoSpawn = true;
_targetRotation = 0;
_rotation = 0;
_randomizeSpeed = false;
//the pool of particles will be the 1.5 times the maximum number of particles will ever be on screen
//with the current spawnrate, spawncount, and lifetime
_particlePool = new Particle[MaxParticles];
for (int i = 0; i < _particlePool.Length; i++)
{
_particlePool[i] = new Particle(_particleImages[_random.Next(0, _particleImages.Length)], _position, _particleTint, _particleSpeed, _scale, _rotation, _lifeTime);
}
}
private void ExpandParticlePool()
{
//if this ever gets called then either SpawnCount, LifeTime, or SpawnRate were changed,
//recalculate the new max size of the array
Particle[] newPool = new Particle[((MaxParticles * 1.5f).ToInt())];
_particlePool.CopyTo(newPool, 0);
int newStartIndex = _particlePool.Length;
_particlePool = newPool;
for (int i = newStartIndex; i < _particlePool.Length; i++)
{
_particlePool[i] = new Particle(_particleImages[_random.Next(0, _particleImages.Length)], _position, _particleTint, _particleSpeed, _scale, _rotation, _lifeTime);
}
}