private static Vector3 CalculateExternalForces(Particle p)
{
// not efficient at all
Vector3 force = new Vector3(0, -GRAVITY * p.Mass, 0);
return force;
}
private void LoadParticleSystem(string configFile)
{
_particles = new List<Particle>();
_constraints = new List<Constraint>();
XmlDocument doc = new XmlDocument();
doc.Load(configFile);
// load transforms
Vector3 translation = GetVectorFromString(doc.SelectSingleNode("/ParticleSystem/Transform").Attributes["Translation"].Value);
Vector3 scale = GetVectorFromString(doc.SelectSingleNode("/ParticleSystem/Transform").Attributes["Scale"].Value);
// load particles
foreach (XmlElement particleElement in doc.SelectNodes("/ParticleSystem/Particles/Particle"))
{
Vector3 position = GetVectorFromString(particleElement.Attributes["Position"].Value);
position *= scale;
position += translation;
Particle particle = new Particle(position, this.Game);
if (particleElement.HasAttribute("Mass"))
{
string massString = particleElement.Attributes["Mass"].Value;
if (massString == "INFINITE_MASS")
particle.Mass = Particle.INFINITE_MASS;
else
particle.Mass = Convert.ToSingle(massString);
}
_particles.Add(particle);
}
// load constraints
foreach (XmlElement constraintElement in doc.SelectNodes("/ParticleSystem/Constraints/*"))
{
string constraintType = constraintElement.Name;
Constraint constraint = null;
switch (constraintType)
{
case "DistanceConstraint" :
Particle particleA = _particles[Convert.ToInt32(constraintElement.Attributes["ParticleA"].Value)];
Particle particleB = _particles[Convert.ToInt32(constraintElement.Attributes["ParticleB"].Value)];
float restLength;
if (constraintElement.HasAttribute("RestLength"))
restLength = Convert.ToSingle(constraintElement.Attributes["RestLength"].Value);
else
restLength = Vector3.Distance(particleA.Position, particleB.Position);
constraint = new DistanceConstraint(this, particleA, particleB, restLength);
if (constraintElement.HasAttribute("Stiffness"))
constraint.Stiffness = Convert.ToSingle(constraintElement.Attributes["Stiffness"].Value);
break;
}
if (constraint != null)
_constraints.Add(constraint);
}
}
private void GenerateCollisionConstraints(Particle p, List<Constraint> collisionConstraints)
{
// collide with terrain
SimpleTerrain terrain = (SimpleTerrain) this.Game.Services.GetService(typeof(SimpleTerrain));
if (terrain != null)
{
float terrainHeight = terrain.GetHeight(p.CandidatePosition.X, p.CandidatePosition.Z);
if (p.CandidatePosition.Y < terrainHeight)
{
collisionConstraints.Add(new GroundCollisionConstraint(this, p, terrainHeight));
p.WasInvolvedInCollision = true;
}
}
// collide with meshes
foreach (GameComponent gameComponent in this.Game.Components)
{
if (gameComponent is Mesh && gameComponent != _graphicObject)
{
Mesh mesh = (Mesh) gameComponent;
if (mesh.BoundingSphere.Contains(p.CandidatePosition) == ContainmentType.Contains)
{
collisionConstraints.Add(new SphereCollisionConstraint(this, p, mesh.BoundingSphere));
p.WasInvolvedInCollision = true;
this._collidedWithMesh = true;
}
}
}
}
public GroundCollisionConstraint(ParticleSystem particleSystem, Particle particle, float terrainHeight)
: this(particleSystem, particle, terrainHeight, 1)
{
}
public GroundCollisionConstraint(ParticleSystem particleSystem, Particle particle, float terrainHeight, float stiffness)
: base(particleSystem, stiffness)
{
_particle = particle;
_terrainHeight = terrainHeight;
}
public SphereCollisionConstraint(ParticleSystem particleSystem, Particle particle, BoundingSphere boundingSphere)
: this(particleSystem, particle, boundingSphere, 1)
{
}
public SphereCollisionConstraint(ParticleSystem particleSystem, Particle particle, BoundingSphere boundingSphere, float stiffness)
: base(particleSystem, stiffness)
{
_particle = particle;
_boundingSphere = boundingSphere;
}
