using System;
using System.Collections.Generic;
using FarseerPhysics.Dynamics;
namespace FarseerPhysics.Controllers
{
///
/// Put a limit on the linear (translation - the movespeed) and angular (rotation) velocity
/// of bodies added to this controller.
///
public class VelocityLimitController : Controller
{
public bool LimitAngularVelocity = true;
public bool LimitLinearVelocity = true;
private List _bodies = new List();
private float _maxAngularSqared;
private float _maxAngularVelocity;
private float _maxLinearSqared;
private float _maxLinearVelocity;
///
/// Initializes a new instance of the class.
/// Sets the max linear velocity to Settings.MaxTranslation
/// Sets the max angular velocity to Settings.MaxRotation
///
public VelocityLimitController()
: base(ControllerType.VelocityLimitController)
{
MaxLinearVelocity = Settings.MaxTranslation;
MaxAngularVelocity = Settings.MaxRotation;
}
///
/// Initializes a new instance of the class.
/// Pass in 0 or float.MaxValue to disable the limit.
/// maxAngularVelocity = 0 will disable the angular velocity limit.
///
/// The max linear velocity.
/// The max angular velocity.
public VelocityLimitController(float maxLinearVelocity, float maxAngularVelocity)
: base(ControllerType.VelocityLimitController)
{
if (maxLinearVelocity == 0 || maxLinearVelocity == float.MaxValue)
LimitLinearVelocity = false;
if (maxAngularVelocity == 0 || maxAngularVelocity == float.MaxValue)
LimitAngularVelocity = false;
MaxLinearVelocity = maxLinearVelocity;
MaxAngularVelocity = maxAngularVelocity;
}
///
/// Gets or sets the max angular velocity.
///
/// The max angular velocity.
public float MaxAngularVelocity
{
get { return _maxAngularVelocity; }
set
{
_maxAngularVelocity = value;
_maxAngularSqared = _maxAngularVelocity * _maxAngularVelocity;
}
}
///
/// Gets or sets the max linear velocity.
///
/// The max linear velocity.
public float MaxLinearVelocity
{
get { return _maxLinearVelocity; }
set
{
_maxLinearVelocity = value;
_maxLinearSqared = _maxLinearVelocity * _maxLinearVelocity;
}
}
public override void Update(float dt)
{
foreach (Body body in _bodies)
{
if (!IsActiveOn(body))
continue;
if (LimitLinearVelocity)
{
//Translation
// Check for large velocities.
float translationX = dt * body.LinearVelocityInternal.X;
float translationY = dt * body.LinearVelocityInternal.Y;
float result = translationX * translationX + translationY * translationY;
if (result > dt * _maxLinearSqared)
{
float sq = (float)Math.Sqrt(result);
float ratio = _maxLinearVelocity / sq;
body.LinearVelocityInternal.X *= ratio;
body.LinearVelocityInternal.Y *= ratio;
}
}
if (LimitAngularVelocity)
{
//Rotation
float rotation = dt * body.AngularVelocityInternal;
if (rotation * rotation > _maxAngularSqared)
{
float ratio = _maxAngularVelocity / Math.Abs(rotation);
body.AngularVelocityInternal *= ratio;
}
}
}
}
public void AddBody(Body body)
{
_bodies.Add(body);
}
public void RemoveBody(Body body)
{
_bodies.Remove(body);
}
}
}