public static void Update(Contexts contexts)
{
var dt = contexts.Configuration().Get <TimeStep>().Value;
var g = contexts.Configuration().Get <GlobalForce>().Value;
var context = contexts.Get <Game>();
foreach (var entity in context.AllWith <Force, Mass, Velocity>())
{
if (entity.Is <Destroyed>())
{
continue;
}
var force = entity.Get <Force>().Value + g;
var mass = entity.Get <Mass>().Value;
var velocity = entity.Get <Velocity>().Value;
var damping = entity.Has <Damping>() ? entity.Get <Damping>().Value : 0;
velocity += dt * force / mass;
velocity *= Fix.One / (Fix.One + dt * damping);
if (entity.Has <MaxVelocity>())
{
var maxVelocity = entity.Get <MaxVelocity>();
velocity = FixVec2.ClampMagnitude(velocity, maxVelocity.Value);
}
entity.Replace(new Velocity(velocity));
entity.Replace(new Force());
}
}
private static SteeringVelocity Arrive(Entity <Game> owner, FixVec2 target)
{
var tolerance = owner.Get <ArrivalTolerance>();
var position = owner.Get <Position>().Value;
target.Sub(ref position);
var distance = target.Magnitude;
if (distance <= tolerance.Distance)
{
return(SteeringVelocity.Zero);
}
var maxVelocity = owner.Get <MaxVelocity>().Value;
var decelerationDistance = tolerance.DecelerationDistance;
if (distance <= decelerationDistance)
{
maxVelocity *= distance / decelerationDistance;
}
var velocity = target / distance * maxVelocity;
return(new SteeringVelocity(FixVec2.ClampMagnitude(velocity, maxVelocity)));
}
public void Limit(Fix maxAcceleration, Fix maxAngularAcceleration)
{
FixVec2.ClampMagnitude(ref Linear, maxAcceleration);
if (Angular > maxAngularAcceleration)
{
Angular = maxAngularAcceleration;
}
}