/// <summary>
/// Deep copy all of the Particle properties
/// </summary>
/// <param name="ParticleToCopy">The Particle to Copy the properties from</param>
public override void CopyFrom(DPSFParticle ParticleToCopy)
{
// Cast the Particle to the type it really is
DefaultSprite3DBillboardParticle cParticleToCopy = (DefaultSprite3DBillboardParticle)ParticleToCopy;
base.CopyFrom(cParticleToCopy);
this.DistanceFromCameraSquared = cParticleToCopy.DistanceFromCameraSquared;
}
//===========================================================
// Particle System Update Functions
//===========================================================
/// <summary>
/// Sorts the particles to draw particles furthest from the camera first, in order to achieve proper depth perspective.
///
/// <para>NOTE: This operation is very expensive and should only be used when you are
/// drawing particles with both opaque and semi-transparent portions, and not using additive blending.</para>
/// <para>Merge Sort is the sorting algorithm used, as it tends to be best for linked lists.
/// TODO - WHILE MERGE SORT SHOULD BE USED, DUE TO TIME CONSTRAINTS A (PROBABLY) SLOWER METHOD (QUICK-SORT)
/// IS BEING USED INSTEAD. THIS FUNCTION NEEDS TO BE UPDATED TO USE MERGE SORT STILL.
/// THE LINKED LIST MERGE SORT ALGORITHM CAN BE FOUND AT http://www.chiark.greenend.org.uk/~sgtatham/algorithms/listsort.html</para>
/// </summary>
/// <param name="fElapsedTimeInSeconds">How long it has been since the last update</param>
protected void UpdateParticleSystemToSortParticlesByDistanceFromCamera(float fElapsedTimeInSeconds)
{
// Store the Number of Active Particles to sort
int iNumberOfActiveParticles = ActiveParticles.Count;
// If there is nothing to sort
if (iNumberOfActiveParticles <= 1)
{
// Exit without sorting
return;
}
// Create a List to put the Active Particles in to be sorted
List <Particle> cActiveParticleList = new List <Particle>(iNumberOfActiveParticles);
// Add all of the Particles to the List
LinkedListNode <Particle> cNode = ActiveParticles.First;
while (cNode != null)
{
// Copy this Particle into the Array
cActiveParticleList.Add(cNode.Value);
// Move to the next Active Particle
cNode = cNode.Next;
}
// Now that the List is full, sort it
cActiveParticleList.Sort(delegate(Particle Particle1, Particle Particle2)
{
DefaultSprite3DBillboardParticle cParticle1 = (DefaultSprite3DBillboardParticle)(DPSFParticle)Particle1;
DefaultSprite3DBillboardParticle cParticle2 = (DefaultSprite3DBillboardParticle)(DPSFParticle)Particle2;
return(cParticle1.DistanceFromCameraSquared.CompareTo(cParticle2.DistanceFromCameraSquared));
});
// Now that the List is sorted, add the Particles into the Active Particles Linked List in sorted order
ActiveParticles.Clear();
for (int iIndex = 0; iIndex < iNumberOfActiveParticles; iIndex++)
{
// Add this Particle to the Active Particles Linked List.
// List is sorted from smallest to largest, but we want
// our Linked List sorted from largest to smallest, since
// the Particles at the end of the Linked List are drawn last.
ActiveParticles.AddFirst(cActiveParticleList[iIndex]);
}
}
//===========================================================
// Draw Sprite and Overridden Particle System Functions
//===========================================================
/// <summary>
/// Function to draw a Sprite Particle. This function should be used to draw the given
/// Particle with the provided SpriteBatch.
/// </summary>
/// <param name="Particle">The Particle Sprite to Draw</param>
/// <param name="cSpriteBatch">The SpriteBatch to use to doing the Drawing</param>
protected override void DrawSprite(DPSFParticle Particle, SpriteBatch cSpriteBatch)
{
// Cast the Particle to the type it really is
DefaultSprite3DBillboardParticle particle = (DefaultSprite3DBillboardParticle)Particle;
// Calculate the sprites position in 3D space, and flip it vertically so that it is not upside-down.
Vector3 viewSpacePosition = Vector3.Transform(particle.Position, this.View);
// Get the Position of the Particle relative to the camera
Vector2 destination = new Vector2(viewSpacePosition.X, viewSpacePosition.Y);
// Get the Position and Dimensions from the Texture to use for this Sprite
Rectangle sourceFromTexture = new Rectangle(0, 0, Texture.Width, Texture.Height);
// Calculate how much to scale the sprite to get it to the desired Width and Height.
// Use negative height in order to flip the texture to be right-side up.
Vector2 scale = new Vector2(particle.Width / sourceFromTexture.Width, -particle.Height / sourceFromTexture.Height);
// Make the Sprite rotate about its center
Vector2 origin = new Vector2(sourceFromTexture.Width / 2, sourceFromTexture.Height / 2);
// Draw the Sprite
cSpriteBatch.Draw(Texture, destination, sourceFromTexture, Color.FromNonPremultiplied(particle.Color.ToVector4()), particle.Rotation, origin, scale, particle.FlipMode, viewSpacePosition.Z);
}
//===========================================================
// Particle Update Functions
//===========================================================
/// <summary>
/// Updates the Particle's DistanceFromCameraSquared property to reflect how far this Particle is from the Camera.
/// </summary>
/// <param name="cParticle">The Particle to update.</param>
/// <param name="fElapsedTimeInSeconds">How long it has been since the last update.</param>
protected void UpdateParticleDistanceFromCameraSquared(DefaultSprite3DBillboardParticle cParticle, float fElapsedTimeInSeconds)
{
cParticle.DistanceFromCameraSquared = Vector3.DistanceSquared(this.CameraPosition, cParticle.Position);
}