private List <Dictionary <int, ParticleInteraction> > GenerateParticleInteractions(int particleTypeCount)
{
var result = new List <Dictionary <int, ParticleInteraction> >();
var particleLifeConfig = (ParticleLifeConfig)spaceConfig;
for (int i = 0; i < particleTypeCount; i++) // Loop every particle type
{
var interactions = new Dictionary <int, ParticleInteraction>();
for (int j = 0; j < particleTypeCount; j++) // For every particle type, it has interaction with every other particle.
{
var interaction = new ParticleInteraction()
{
GraphDots = new List <Vector2>()
};
for (int k = 0; k < particleLifeConfig.MinimumParticleInteractions.Count; k++) // Generate all graph dots...
{
var xVal = RNG.RandomFloat(particleLifeConfig.MinimumParticleInteractionDistances[k], particleLifeConfig.MaximumParticleInteractionDistances[k]);
var yVal = RNG.RandomFloat(particleLifeConfig.MinimumParticleInteractions[k], particleLifeConfig.MaximumParticleInteractions[k]);
interaction.GraphDots.Add(new Vector2(xVal, yVal));
}
interactions.Add(j, interaction); // Add to interactions
}
result.Add(interactions);
}
return(result);
}
// UPDATE STEPS
void SatisfyConstraints()
{
// Using a reverse loop allows us to safely remove constraints from the list
for (int interactionIndex = particleInteractions.Count - 1; interactionIndex >= 0; interactionIndex--)
{
ParticleInteraction interaction = particleInteractions[interactionIndex];
// Only satisfy constraints for enabled interactions
if (!simulationManager.GetSpringForce(interaction.interactionType).enabled)
{
continue;
}
// If tearing, check how far apart the particles are and maybe remove them from the list
if (constants.enableTearing)
{
float magnitude = (particles[interaction.particle1].Position - particles[interaction.particle2].Position).magnitude;
if (magnitude > interaction.equilibriumDistance * constants.maxTearingRatio)
{
particleInteractions.RemoveAt(interactionIndex);
// Don't satisfy this constraint, since they it's broken now
continue;
}
}
SatisfyConstraint(interaction);
}
}
// UPDATE STEPS
void AddInternalForces()
{
for (int interactionIndex = particleInteractions.Count - 1; interactionIndex >= 0; interactionIndex--)
{
// Using a reverse loop allows us to safely remove items from the indices list
ParticleInteraction interaction = particleInteractions[interactionIndex];
SpringForceSettings springForceOfInteraction = simulationManager.GetSpringForce(interaction.interactionType);
if (springForceOfInteraction.enabled)
{
EulerParticle particle1 = particles[interaction.particle1];
EulerParticle particle2 = particles[interaction.particle2];
Vector3 direction = particle1.Position - particle2.Position;
float magnitude = direction.magnitude;
// Cloth ripping
if (constants.enableTearing && magnitude > interaction.equilibriumDistance * constants.maxTearingRatio)
{
// Break the connection (we could do the same for the reverse one). No force added.
particleInteractions.RemoveAt(interactionIndex);
continue;
}
Vector3 force = direction / magnitude * (interaction.equilibriumDistance - magnitude) * springForceOfInteraction.forceConstant;
Vector3 dampingForce = (particles[interaction.particle2].velocity - particles[interaction.particle1].velocity) * constants.springDampingConstant;
particle1.AddForce(force + dampingForce);
}
}
}
public void TestInterpolation()
{
var left = new Vector2(1, 2);
var right = new Vector2(4, 7);
var searchPoint = 3.0f;
var interaction = new ParticleInteraction();
interaction.GraphDots = new List <Vector2>();
interaction.GraphDots.Add(left);
interaction.GraphDots.Add(right);
Assert.AreEqual(interaction.GetInteraction(searchPoint),
(left.Y + ((searchPoint - left.X) / (right.X - left.X)) * (right.Y - left.Y))
);
}
// CONSTRAINTS
void SatisfyConstraint(ParticleInteraction interaction)
{
VerletParticle particle1 = particles[interaction.particle1];
VerletParticle particle2 = particles[interaction.particle2];
// Correction vector from particle1 -> particle2
Vector3 directionVector = particle2.Position - particle1.Position;
Vector3 correctionVector = (1 - interaction.equilibriumDistance / directionVector.magnitude) * directionVector;
// Apply half the correction to each particle (unless one is fixed)
if (!particle1.isFixed && !particle2.isFixed)
{
particle1.Position += correctionVector / 2;
particle2.Position -= correctionVector / 2;
}
else if (particle1.isFixed && !particle2.isFixed)
{
particle2.Position -= correctionVector;
}
else if (!particle1.isFixed && particle2.isFixed)
{
particle1.Position += correctionVector;
}
}
