public IEnumerator EndcapForceSign()
{
LinearElasticSystem les = new LinearElasticSystem(0.0f, 0.0f, extentProperties, elasticProperties);
// Goal position for the elastic system to stretch towards
var goalValue = 15.0f;
// Let the elastic system come to an equilibrium.
// No need for yielding for new frames because the elastic system
// simlulates independently from Unity's frame system.
for (int i = 0; i < 50; i++)
{
les.ComputeIteration(goalValue, 0.1f);
}
// Get the equilibrium value from the system.
var equilibrium = les.GetCurrentValue();
Debug.Assert(equilibrium < goalValue, $"Stretching beyond max limit should result in equilibrium value less than goal value, equilibrium: {equilibrium}");
// Compute one small iteration, covering 50 milliseconds.
var newValue = les.ComputeIteration(equilibrium, 0.05f);
// The system should have shrunk back towards the endpoint.
Debug.Assert(newValue < equilibrium, $"Elastic system should have contracted towards endpoint when released, actual value: {newValue}, equilibrium: {equilibrium}");
Debug.Assert(les.GetCurrentVelocity() < 0.0f, $"Elastic system should now have negative velocity, actual velocity: {les.GetCurrentVelocity()}");
// Compute one more small iteration (50 milliseconds)
var secondNewValue = les.ComputeIteration(equilibrium, 0.05f);
// The system should have shrunk back towards the endpoint.
Debug.Assert(secondNewValue < equilibrium, $"Elastic system should have contracted towards endpoint when released, actual value: {secondNewValue}, equilibrium: {equilibrium}");
Debug.Assert(secondNewValue < newValue, $"Elastic system should have contracted further towards endpoint, new value: {secondNewValue}, last value: {newValue}");
Debug.Assert(les.GetCurrentVelocity() < 0.0f, $"Elastic system should still have negative velocity, actual velocity: {les.GetCurrentVelocity()}");
// Now, we test pulling the elastic negative, and performing similar checks.
goalValue = -5.0f;
// Let the elastic system come to an equilibrium
for (int i = 0; i < 50; i++)
{
les.ComputeIteration(goalValue, 0.1f);
}
// Get the equilibrium value from the system.
equilibrium = les.GetCurrentValue();
Debug.Assert(equilibrium > goalValue, $"Stretching beyond minimum limit should result in equilibrium value greater than goal value, equilibrium: {equilibrium}");
// Compute one small iteration, covering 50 milliseconds.
newValue = les.ComputeIteration(equilibrium, 0.05f);
// The system should have shrunk back towards the endpoint.
Debug.Assert(newValue > equilibrium, $"Elastic system should have contracted towards endpoint when released, actual value: {newValue}, equilibrium: {equilibrium}");
Debug.Assert(les.GetCurrentVelocity() > 0.0f, $"Elastic system should now have positive velocity, actual velocity: {les.GetCurrentVelocity()}");
// Compute one more small iteration (50 milliseconds)
secondNewValue = les.ComputeIteration(equilibrium, 0.05f);
// The system should have shrunk back towards the endpoint.
Debug.Assert(secondNewValue > equilibrium, $"Elastic system should have contracted towards endpoint when released, actual value: {secondNewValue}, equilibrium: {equilibrium}");
Debug.Assert(secondNewValue > newValue, $"Elastic system should have contracted further towards endpoint, new value: {secondNewValue}, last value: {newValue}");
Debug.Assert(les.GetCurrentVelocity() > 0.0f, $"Elastic system should still have positive velocity, actual velocity: {les.GetCurrentVelocity()}");
yield return(null);
}
public IEnumerator EndpointSnapping()
{
// Default extent properties have SnapToEnd set to false.
LinearElasticSystem les = new LinearElasticSystem(0.0f, 0.0f, extentProperties, elasticProperties);
// Goal position for the elastic system to seek.
// We will let the system settle to right next to the endpoint.
var goalValue = 9.5f;
// Let the elastic system come to an equilibrium.
// No need for yielding for new frames because the elastic system
// simlulates independently from Unity's frame system.
for (int i = 0; i < 1000; i++)
{
les.ComputeIteration(goalValue, 0.05f);
}
// Get the equilibrium value from the system.
// It should be basically equal to the goal value, given that endpoint snapping is disabled.
var equilibrium = les.GetCurrentValue();
Assert.AreApproximatelyEqual(goalValue, les.GetCurrentValue(), $"Equilibrium should be roughly equal to goal value. Goal: {goalValue}");
// Compute one small iteration, covering 50 milliseconds.
var newValue = les.ComputeIteration(equilibrium, 0.05f);
// The system should have stayed still.
Assert.AreApproximatelyEqual(newValue, equilibrium, $"Elastic system should have stayed mostly still when released, actual value: {newValue}, equilibrium: {equilibrium}");
Assert.AreApproximatelyEqual(les.GetCurrentVelocity(), 0.0f, $"Elastic system should have zero velocity, actual velocity: {les.GetCurrentVelocity()}");
// Copy the extent properties, but now we enable end snapping.
var newExtentProperties = extentProperties;
newExtentProperties.SnapToEnds = true;
// Create new system.
les = new LinearElasticSystem(0.0f, 0.0f, newExtentProperties, elasticProperties);
// Again, right next to the endpoint.
goalValue = 9.5f;
// Let the elastic system come to an equilibrium.
for (int i = 0; i < 1000; i++)
{
les.ComputeIteration(goalValue, 0.05f);
}
// Get the equilibrium value from the system.
// It should now be slightly bigger than the goal value, due to endpoint snapping.
equilibrium = les.GetCurrentValue();
Debug.Assert(equilibrium > goalValue, $"Equilibrium should be slightly greater than goal value. Goal: {goalValue}, Current: {equilibrium}");
Debug.Assert(equilibrium < 10.0f, $"Equilibrium should still be less than the endpoint value");
// Compute one small iteration, covering 50 milliseconds.
newValue = les.ComputeIteration(equilibrium, 0.05f);
// The system should have moved towards the endpoint
Debug.Assert(newValue > equilibrium, $"Elastic system should snap towards endpoint, actual value: {newValue}, equilibrium: {equilibrium}");
Debug.Assert(les.GetCurrentVelocity() > 0.0f, $"Elastic system should have positive velocity, actual velocity: {les.GetCurrentVelocity()}");
yield return(null);
}