480 lines
20 KiB
C#
480 lines
20 KiB
C#
/*
|
|
* Farseer Physics Engine:
|
|
* Copyright (c) 2012 Ian Qvist
|
|
*
|
|
* Original source Box2D:
|
|
* Copyright (c) 2006-2011 Erin Catto http://www.box2d.org
|
|
*
|
|
* This software is provided 'as-is', without any express or implied
|
|
* warranty. In no event will the authors be held liable for any damages
|
|
* arising from the use of this software.
|
|
* Permission is granted to anyone to use this software for any purpose,
|
|
* including commercial applications, and to alter it and redistribute it
|
|
* freely, subject to the following restrictions:
|
|
* 1. The origin of this software must not be misrepresented; you must not
|
|
* claim that you wrote the original software. If you use this software
|
|
* in a product, an acknowledgment in the product documentation would be
|
|
* appreciated but is not required.
|
|
* 2. Altered source versions must be plainly marked as such, and must not be
|
|
* misrepresented as being the original software.
|
|
* 3. This notice may not be removed or altered from any source distribution.
|
|
*/
|
|
//#define USE_ACTIVE_CONTACT_SET
|
|
|
|
using System.Collections.Generic;
|
|
using System.Diagnostics;
|
|
using FarseerPhysics.Collision;
|
|
using FarseerPhysics.Collision.Shapes;
|
|
using FarseerPhysics.Common;
|
|
using Microsoft.Xna.Framework;
|
|
|
|
namespace FarseerPhysics.Dynamics.Contacts
|
|
{
|
|
/// <summary>
|
|
/// A contact edge is used to connect bodies and contacts together
|
|
/// in a contact graph where each body is a node and each contact
|
|
/// is an edge. A contact edge belongs to a doubly linked list
|
|
/// maintained in each attached body. Each contact has two contact
|
|
/// nodes, one for each attached body.
|
|
/// </summary>
|
|
public sealed class ContactEdge
|
|
{
|
|
/// <summary>
|
|
/// The contact
|
|
/// </summary>
|
|
public Contact Contact;
|
|
|
|
/// <summary>
|
|
/// The next contact edge in the body's contact list
|
|
/// </summary>
|
|
public ContactEdge Next;
|
|
|
|
/// <summary>
|
|
/// Provides quick access to the other body attached.
|
|
/// </summary>
|
|
public Body Other;
|
|
|
|
/// <summary>
|
|
/// The previous contact edge in the body's contact list
|
|
/// </summary>
|
|
public ContactEdge Prev;
|
|
}
|
|
|
|
/// <summary>
|
|
/// The class manages contact between two shapes. A contact exists for each overlapping
|
|
/// AABB in the broad-phase (except if filtered). Therefore a contact object may exist
|
|
/// that has no contact points.
|
|
/// </summary>
|
|
public class Contact
|
|
{
|
|
private ContactType _type;
|
|
|
|
private static EdgeShape _edge = new EdgeShape();
|
|
|
|
private static ContactType[,] _registers = new[,]
|
|
{
|
|
{
|
|
ContactType.Circle,
|
|
ContactType.EdgeAndCircle,
|
|
ContactType.PolygonAndCircle,
|
|
ContactType.ChainAndCircle,
|
|
},
|
|
{
|
|
ContactType.EdgeAndCircle,
|
|
ContactType.NotSupported,
|
|
// 1,1 is invalid (no ContactType.Edge)
|
|
ContactType.EdgeAndPolygon,
|
|
ContactType.NotSupported,
|
|
// 1,3 is invalid (no ContactType.EdgeAndLoop)
|
|
},
|
|
{
|
|
ContactType.PolygonAndCircle,
|
|
ContactType.EdgeAndPolygon,
|
|
ContactType.Polygon,
|
|
ContactType.ChainAndPolygon,
|
|
},
|
|
{
|
|
ContactType.ChainAndCircle,
|
|
ContactType.NotSupported,
|
|
// 3,1 is invalid (no ContactType.EdgeAndLoop)
|
|
ContactType.ChainAndPolygon,
|
|
ContactType.NotSupported,
|
|
// 3,3 is invalid (no ContactType.Loop)
|
|
},
|
|
};
|
|
// Nodes for connecting bodies.
|
|
internal ContactEdge _nodeA = new ContactEdge();
|
|
internal ContactEdge _nodeB = new ContactEdge();
|
|
internal int _toiCount;
|
|
internal float _toi;
|
|
|
|
public Fixture FixtureA;
|
|
public Fixture FixtureB;
|
|
public float Friction { get; set; }
|
|
public float Restitution { get; set; }
|
|
|
|
/// <summary>
|
|
/// Get the contact manifold. Do not modify the manifold unless you understand the
|
|
/// internals of Box2D.
|
|
/// </summary>
|
|
public Manifold Manifold;
|
|
|
|
/// Get or set the desired tangent speed for a conveyor belt behavior. In meters per second.
|
|
public float TangentSpeed { get; set; }
|
|
|
|
/// Enable/disable this contact. This can be used inside the pre-solve
|
|
/// contact listener. The contact is only disabled for the current
|
|
/// time step (or sub-step in continuous collisions).
|
|
/// NOTE: If you are setting Enabled to a constant true or false,
|
|
/// use the explicit Enable() or Disable() functions instead to
|
|
/// save the CPU from doing a branch operation.
|
|
public bool Enabled { get; set; }
|
|
|
|
/// <summary>
|
|
/// Get the child primitive index for fixture A.
|
|
/// </summary>
|
|
/// <value>The child index A.</value>
|
|
public int ChildIndexA { get; internal set; }
|
|
|
|
/// <summary>
|
|
/// Get the child primitive index for fixture B.
|
|
/// </summary>
|
|
/// <value>The child index B.</value>
|
|
public int ChildIndexB { get; internal set; }
|
|
|
|
/// <summary>
|
|
/// Determines whether this contact is touching.
|
|
/// </summary>
|
|
/// <returns>
|
|
/// <c>true</c> if this instance is touching; otherwise, <c>false</c>.
|
|
/// </returns>
|
|
public bool IsTouching { get; set; }
|
|
|
|
internal bool IslandFlag { get; set; }
|
|
internal bool TOIFlag { get; set; }
|
|
internal bool FilterFlag { get; set; }
|
|
|
|
public void ResetRestitution()
|
|
{
|
|
Restitution = Settings.MixRestitution(FixtureA.Restitution, FixtureB.Restitution);
|
|
}
|
|
|
|
public void ResetFriction()
|
|
{
|
|
Friction = Settings.MixFriction(FixtureA.Friction, FixtureB.Friction);
|
|
}
|
|
|
|
private Contact(Fixture fA, int indexA, Fixture fB, int indexB)
|
|
{
|
|
Reset(fA, indexA, fB, indexB);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Gets the world manifold.
|
|
/// </summary>
|
|
public void GetWorldManifold(out Vector2 normal, out FixedArray2<Vector2> points)
|
|
{
|
|
Body bodyA = FixtureA.Body;
|
|
Body bodyB = FixtureB.Body;
|
|
Shape shapeA = FixtureA.Shape;
|
|
Shape shapeB = FixtureB.Shape;
|
|
|
|
ContactSolver.WorldManifold.Initialize(ref Manifold, ref bodyA._xf, shapeA.Radius, ref bodyB._xf, shapeB.Radius, out normal, out points);
|
|
}
|
|
|
|
private void Reset(Fixture fA, int indexA, Fixture fB, int indexB)
|
|
{
|
|
Enabled = true;
|
|
IsTouching = false;
|
|
IslandFlag = false;
|
|
FilterFlag = false;
|
|
TOIFlag = false;
|
|
|
|
FixtureA = fA;
|
|
FixtureB = fB;
|
|
|
|
ChildIndexA = indexA;
|
|
ChildIndexB = indexB;
|
|
|
|
Manifold.PointCount = 0;
|
|
|
|
_nodeA.Contact = null;
|
|
_nodeA.Prev = null;
|
|
_nodeA.Next = null;
|
|
_nodeA.Other = null;
|
|
|
|
_nodeB.Contact = null;
|
|
_nodeB.Prev = null;
|
|
_nodeB.Next = null;
|
|
_nodeB.Other = null;
|
|
|
|
_toiCount = 0;
|
|
|
|
//FPE: We only set the friction and restitution if we are not destroying the contact
|
|
if (FixtureA != null && FixtureB != null)
|
|
{
|
|
Friction = Settings.MixFriction(FixtureA.Friction, FixtureB.Friction);
|
|
Restitution = Settings.MixRestitution(FixtureA.Restitution, FixtureB.Restitution);
|
|
}
|
|
|
|
TangentSpeed = 0;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Update the contact manifold and touching status.
|
|
/// Note: do not assume the fixture AABBs are overlapping or are valid.
|
|
/// </summary>
|
|
/// <param name="contactManager">The contact manager.</param>
|
|
internal void Update(ContactManager contactManager)
|
|
{
|
|
Body bodyA = FixtureA.Body;
|
|
Body bodyB = FixtureB.Body;
|
|
|
|
if (FixtureA == null || FixtureB == null)
|
|
return;
|
|
|
|
Manifold oldManifold = Manifold;
|
|
|
|
// Re-enable this contact.
|
|
Enabled = true;
|
|
|
|
bool touching;
|
|
bool wasTouching = IsTouching;
|
|
|
|
bool sensor = FixtureA.IsSensor || FixtureB.IsSensor;
|
|
|
|
// Is this contact a sensor?
|
|
if (sensor)
|
|
{
|
|
Shape shapeA = FixtureA.Shape;
|
|
Shape shapeB = FixtureB.Shape;
|
|
touching = Collision.Collision.TestOverlap(shapeA, ChildIndexA, shapeB, ChildIndexB, ref bodyA._xf, ref bodyB._xf);
|
|
|
|
// Sensors don't generate manifolds.
|
|
Manifold.PointCount = 0;
|
|
}
|
|
else
|
|
{
|
|
Evaluate(ref Manifold, ref bodyA._xf, ref bodyB._xf);
|
|
touching = Manifold.PointCount > 0;
|
|
|
|
// Match old contact ids to new contact ids and copy the
|
|
// stored impulses to warm start the solver.
|
|
for (int i = 0; i < Manifold.PointCount; ++i)
|
|
{
|
|
ManifoldPoint mp2 = Manifold.Points[i];
|
|
mp2.NormalImpulse = 0.0f;
|
|
mp2.TangentImpulse = 0.0f;
|
|
ContactID id2 = mp2.Id;
|
|
|
|
for (int j = 0; j < oldManifold.PointCount; ++j)
|
|
{
|
|
ManifoldPoint mp1 = oldManifold.Points[j];
|
|
|
|
if (mp1.Id.Key == id2.Key)
|
|
{
|
|
mp2.NormalImpulse = mp1.NormalImpulse;
|
|
mp2.TangentImpulse = mp1.TangentImpulse;
|
|
break;
|
|
}
|
|
}
|
|
|
|
Manifold.Points[i] = mp2;
|
|
}
|
|
|
|
if (touching != wasTouching)
|
|
{
|
|
bodyA.Awake = true;
|
|
bodyB.Awake = true;
|
|
}
|
|
}
|
|
|
|
IsTouching = touching;
|
|
|
|
if (wasTouching == false)
|
|
{
|
|
if (touching)
|
|
{
|
|
if (Settings.AllCollisionCallbacksAgree)
|
|
{
|
|
bool enabledA = true, enabledB = true;
|
|
|
|
// Report the collision to both participants. Track which ones returned true so we can
|
|
// later call OnSeparation if the contact is disabled for a different reason.
|
|
if (FixtureA.OnCollision != null)
|
|
foreach (OnCollisionEventHandler handler in FixtureA.OnCollision.GetInvocationList())
|
|
enabledA = handler(FixtureA, FixtureB, this) && enabledA;
|
|
|
|
// Reverse the order of the reported fixtures. The first fixture is always the one that the
|
|
// user subscribed to.
|
|
if (FixtureB.OnCollision != null)
|
|
foreach (OnCollisionEventHandler handler in FixtureB.OnCollision.GetInvocationList())
|
|
enabledB = handler(FixtureB, FixtureA, this) && enabledB;
|
|
|
|
Enabled = enabledA && enabledB;
|
|
|
|
// BeginContact can also return false and disable the contact
|
|
if (enabledA && enabledB && contactManager.BeginContact != null)
|
|
Enabled = contactManager.BeginContact(this);
|
|
}
|
|
else
|
|
{
|
|
//Report the collision to both participants:
|
|
if (FixtureA.OnCollision != null)
|
|
foreach (OnCollisionEventHandler handler in FixtureA.OnCollision.GetInvocationList())
|
|
Enabled = handler(FixtureA, FixtureB, this);
|
|
|
|
//Reverse the order of the reported fixtures. The first fixture is always the one that the
|
|
//user subscribed to.
|
|
if (FixtureB.OnCollision != null)
|
|
foreach (OnCollisionEventHandler handler in FixtureB.OnCollision.GetInvocationList())
|
|
Enabled = handler(FixtureB, FixtureA, this);
|
|
|
|
//BeginContact can also return false and disable the contact
|
|
if (contactManager.BeginContact != null)
|
|
Enabled = contactManager.BeginContact(this);
|
|
}
|
|
|
|
// If the user disabled the contact (needed to exclude it in TOI solver) at any point by
|
|
// any of the callbacks, we need to mark it as not touching and call any separation
|
|
// callbacks for fixtures that didn't explicitly disable the collision.
|
|
if (!Enabled)
|
|
IsTouching = false;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if (touching == false)
|
|
{
|
|
//Report the separation to both participants:
|
|
if (FixtureA != null && FixtureA.OnSeparation != null)
|
|
FixtureA.OnSeparation(FixtureA, FixtureB);
|
|
|
|
//Reverse the order of the reported fixtures. The first fixture is always the one that the
|
|
//user subscribed to.
|
|
if (FixtureB != null && FixtureB.OnSeparation != null)
|
|
FixtureB.OnSeparation(FixtureB, FixtureA);
|
|
|
|
if (contactManager.EndContact != null)
|
|
contactManager.EndContact(this);
|
|
}
|
|
}
|
|
|
|
if (sensor)
|
|
return;
|
|
|
|
if (contactManager.PreSolve != null)
|
|
contactManager.PreSolve(this, ref oldManifold);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Evaluate this contact with your own manifold and transforms.
|
|
/// </summary>
|
|
/// <param name="manifold">The manifold.</param>
|
|
/// <param name="transformA">The first transform.</param>
|
|
/// <param name="transformB">The second transform.</param>
|
|
private void Evaluate(ref Manifold manifold, ref Transform transformA, ref Transform transformB)
|
|
{
|
|
switch (_type)
|
|
{
|
|
case ContactType.Polygon:
|
|
Collision.Collision.CollidePolygons(ref manifold, (PolygonShape)FixtureA.Shape, ref transformA, (PolygonShape)FixtureB.Shape, ref transformB);
|
|
break;
|
|
case ContactType.PolygonAndCircle:
|
|
Collision.Collision.CollidePolygonAndCircle(ref manifold, (PolygonShape)FixtureA.Shape, ref transformA, (CircleShape)FixtureB.Shape, ref transformB);
|
|
break;
|
|
case ContactType.EdgeAndCircle:
|
|
Collision.Collision.CollideEdgeAndCircle(ref manifold, (EdgeShape)FixtureA.Shape, ref transformA, (CircleShape)FixtureB.Shape, ref transformB);
|
|
break;
|
|
case ContactType.EdgeAndPolygon:
|
|
Collision.Collision.CollideEdgeAndPolygon(ref manifold, (EdgeShape)FixtureA.Shape, ref transformA, (PolygonShape)FixtureB.Shape, ref transformB);
|
|
break;
|
|
case ContactType.ChainAndCircle:
|
|
ChainShape chain = (ChainShape)FixtureA.Shape;
|
|
chain.GetChildEdge(_edge, ChildIndexA);
|
|
Collision.Collision.CollideEdgeAndCircle(ref manifold, _edge, ref transformA, (CircleShape)FixtureB.Shape, ref transformB);
|
|
break;
|
|
case ContactType.ChainAndPolygon:
|
|
ChainShape loop2 = (ChainShape)FixtureA.Shape;
|
|
loop2.GetChildEdge(_edge, ChildIndexA);
|
|
Collision.Collision.CollideEdgeAndPolygon(ref manifold, _edge, ref transformA, (PolygonShape)FixtureB.Shape, ref transformB);
|
|
break;
|
|
case ContactType.Circle:
|
|
Collision.Collision.CollideCircles(ref manifold, (CircleShape)FixtureA.Shape, ref transformA, (CircleShape)FixtureB.Shape, ref transformB);
|
|
break;
|
|
}
|
|
}
|
|
|
|
internal static Contact Create(Fixture fixtureA, int indexA, Fixture fixtureB, int indexB)
|
|
{
|
|
ShapeType type1 = fixtureA.Shape.ShapeType;
|
|
ShapeType type2 = fixtureB.Shape.ShapeType;
|
|
|
|
Debug.Assert(ShapeType.Unknown < type1 && type1 < ShapeType.TypeCount);
|
|
Debug.Assert(ShapeType.Unknown < type2 && type2 < ShapeType.TypeCount);
|
|
|
|
Contact c;
|
|
Queue<Contact> pool = fixtureA.Body._world._contactPool;
|
|
if (pool.Count > 0)
|
|
{
|
|
c = pool.Dequeue();
|
|
if ((type1 >= type2 || (type1 == ShapeType.Edge && type2 == ShapeType.Polygon)) && !(type2 == ShapeType.Edge && type1 == ShapeType.Polygon))
|
|
{
|
|
c.Reset(fixtureA, indexA, fixtureB, indexB);
|
|
}
|
|
else
|
|
{
|
|
c.Reset(fixtureB, indexB, fixtureA, indexA);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
// Edge+Polygon is non-symetrical due to the way Erin handles collision type registration.
|
|
if ((type1 >= type2 || (type1 == ShapeType.Edge && type2 == ShapeType.Polygon)) && !(type2 == ShapeType.Edge && type1 == ShapeType.Polygon))
|
|
{
|
|
c = new Contact(fixtureA, indexA, fixtureB, indexB);
|
|
}
|
|
else
|
|
{
|
|
c = new Contact(fixtureB, indexB, fixtureA, indexA);
|
|
}
|
|
}
|
|
|
|
c._type = _registers[(int)type1, (int)type2];
|
|
|
|
return c;
|
|
}
|
|
|
|
internal void Destroy()
|
|
{
|
|
#if USE_ACTIVE_CONTACT_SET
|
|
FixtureA.Body.World.ContactManager.RemoveActiveContact(this);
|
|
#endif
|
|
FixtureA.Body._world._contactPool.Enqueue(this);
|
|
|
|
if (Manifold.PointCount > 0 && FixtureA.IsSensor == false && FixtureB.IsSensor == false)
|
|
{
|
|
FixtureA.Body.Awake = true;
|
|
FixtureB.Body.Awake = true;
|
|
}
|
|
|
|
Reset(null, 0, null, 0);
|
|
}
|
|
|
|
#region Nested type: ContactType
|
|
|
|
private enum ContactType
|
|
{
|
|
NotSupported,
|
|
Polygon,
|
|
PolygonAndCircle,
|
|
Circle,
|
|
EdgeAndPolygon,
|
|
EdgeAndCircle,
|
|
ChainAndPolygon,
|
|
ChainAndCircle,
|
|
}
|
|
|
|
#endregion
|
|
}
|
|
} |