private static void ApplyMoment(SectionForceInput input)
{
Vector3 moment = input.worldAxis * input.force;
input.section.Moment += moment;
if (!input.body)
{
return;
}
input.body.AddTorqueAtPosition(moment, input.worldAxisZero, input.sectionWorldPosition, ForceMode.Force);
}
private static void ApplyDrag(SectionForceInput input)
{
Vector3 drag = input.sectionRelativeDirection * -input.force;
input.section.Drag += drag;
if (!input.body)
{
return;
}
input.body.AddForceAtPosition(drag, input.sectionWorldPosition);
}
// Todo: We might be able to skip a normalize and a scale operation if we use RelativeVelocity instead of RelativeDirection+Magnitude breakup
private static void ApplyLift(SectionForceInput input)
{
Vector3 liftDirection = Vector3.Cross(input.sectionRelativeDirection, input.worldAxis);
float liftMagnitude = input.force * Mathf.Pow(input.efficiency, 2f);
Vector3 lift = liftDirection * liftMagnitude;
input.section.Lift += lift;
if (!input.body)
{
return;
}
input.body.AddForceAtPosition(lift, input.sectionWorldPosition);
}
private void EvaluateForces()
{
Transform wingTransform = transform;
Vector3 wingPosition = wingTransform.position;
Vector3 windVelocity = _wind.GetWindVelocity(wingPosition);
float airDensity = _wind.GetAirDensity(wingPosition);
Vector3 velocity = (wingPosition - _lastPosition) / Time.deltaTime;
_lastPosition = wingPosition;
RelativeVelocity = velocity - windVelocity;
AirSpeed = RelativeVelocity.magnitude;
const float groundEffectHeight = 32f;
const float groundEffectPow = 2f;
float groundEffectMultiplier = 1f;
RaycastHit hit;
if (Physics.Raycast(_body.transform.position, Vector3.down, out hit, groundEffectHeight, _layerMask))
{
groundEffectMultiplier += Mathf.Pow(Mathf.InverseLerp(groundEffectHeight, 0f, hit.distance), groundEffectPow);
}
UpdateStats(wingTransform);
// Calculate forces per section of the wing
for (int i = 0; i < _numSections; i++)
{
var section = _sectionStates[i];
Vector3 sectionWorldPosition = wingTransform.TransformPoint(section.LocalPosition);
Vector3 sectionWorldVelocity = (sectionWorldPosition - section.LastSectionWorldPosition) / Time.fixedDeltaTime;
section.LastSectionWorldPosition = sectionWorldPosition;
section.RelativeVelocity = sectionWorldVelocity - windVelocity;
section.AirSpeed = section.RelativeVelocity.magnitude;
float dynamicPressure = 0.5f * airDensity * section.AirSpeed * section.AirSpeed * groundEffectMultiplier;
section.Lift = Vector3.zero;
section.Drag = Vector3.zero;
section.Moment = Vector3.zero;
//Vector3 localRelativeVelocity = wingTransform.InverseTransformDirection(section.RelativeVelocity);
// Calculate the effects around each axis
for (int j = 0; j < _components.Length; j++)
{
AirfoilAxisResponse coefficient = _components[j];
AirfoilAxis airfoilAxis = _axes[(int)coefficient.AxisType];
Vector3 worldAxis = wingTransform.TransformDirection(airfoilAxis.Axis);
Vector3 worldAxisBase = wingTransform.TransformDirection(airfoilAxis.AxisZero);
// Todo: Collapse this all into 2D calculations around the coefficient axis
Vector3 projectedVelocity = section.RelativeVelocity - Vector3.Project(section.RelativeVelocity, worldAxis);
section.AngleOfAttack = MathUtils.AngleAroundAxis(worldAxisBase, projectedVelocity, worldAxis);
Vector3 sectionRelativeDirection = projectedVelocity.normalized;
float forceCoefficient = coefficient.Coefficients.Evaluate(section.AngleOfAttack + section.Offset) * coefficient.Multiplier;
float forceMagnitude = dynamicPressure * section.SurfaceArea * forceCoefficient;
var input = new SectionForceInput()
{
body = _body,
force = forceMagnitude,
efficiency = _efficiency,
section = section,
sectionWorldPosition = sectionWorldPosition,
sectionRelativeDirection = sectionRelativeDirection,
worldAxis = worldAxis,
worldAxisZero = worldAxisBase
};
//ForceApplicators[(int) coefficient.Type](input);
switch (coefficient.Type)
{
case ForceType.Lift:
ApplyLift(input);
break;
case ForceType.Drag:
ApplyDrag(input);
break;
case ForceType.Moment:
ApplyMoment(input);
break;
}
}
}
}