611 lines
20 KiB
C#
611 lines
20 KiB
C#
/*
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* Farseer Physics Engine based on Box2D.XNA port:
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* Copyright (c) 2010 Ian Qvist
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*
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* Box2D.XNA port of Box2D:
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* Copyright (c) 2009 Brandon Furtwangler, Nathan Furtwangler
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*
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* Original source Box2D:
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* Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgment in the product documentation would be
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* appreciated but is not required.
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* 2. Altered source versions must be plainly marked as such, and must not be
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* misrepresented as being the original software.
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* 3. This notice may not be removed or altered from any source distribution.
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*/
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using FarseerPhysics.Collision;
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using FarseerPhysics.Collision.Shapes;
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using FarseerPhysics.Common;
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using FarseerPhysics.Dynamics.Contacts;
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using Microsoft.Xna.Framework;
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namespace FarseerPhysics.Dynamics
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{
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[Flags]
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public enum Category
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{
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None = 0,
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All = int.MaxValue,
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Cat1 = 1,
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Cat2 = 2,
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Cat3 = 4,
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Cat4 = 8,
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Cat5 = 16,
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Cat6 = 32,
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Cat7 = 64,
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Cat8 = 128,
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Cat9 = 256,
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Cat10 = 512,
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Cat11 = 1024,
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Cat12 = 2048,
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Cat13 = 4096,
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Cat14 = 8192,
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Cat15 = 16384,
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Cat16 = 32768,
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Cat17 = 65536,
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Cat18 = 131072,
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Cat19 = 262144,
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Cat20 = 524288,
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Cat21 = 1048576,
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Cat22 = 2097152,
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Cat23 = 4194304,
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Cat24 = 8388608,
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Cat25 = 16777216,
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Cat26 = 33554432,
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Cat27 = 67108864,
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Cat28 = 134217728,
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Cat29 = 268435456,
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Cat30 = 536870912,
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Cat31 = 1073741824
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}
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/// <summary>
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/// This proxy is used internally to connect fixtures to the broad-phase.
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/// </summary>
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public struct FixtureProxy
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{
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public AABB AABB;
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public int ChildIndex;
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public Fixture Fixture;
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public int ProxyId;
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}
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/// <summary>
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/// A fixture is used to attach a Shape to a body for collision detection. A fixture
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/// inherits its transform from its parent. Fixtures hold additional non-geometric data
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/// such as friction, collision filters, etc.
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/// Fixtures are created via Body.CreateFixture.
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/// Warning: You cannot reuse fixtures.
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/// </summary>
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public class Fixture : IDisposable
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{
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private static int _fixtureIdCounter;
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/// <summary>
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/// Fires after two shapes has collided and are solved. This gives you a chance to get the impact force.
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/// </summary>
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public AfterCollisionEventHandler AfterCollision;
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/// <summary>
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/// Fires when two fixtures are close to each other.
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/// Due to how the broadphase works, this can be quite inaccurate as shapes are approximated using AABBs.
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/// </summary>
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public BeforeCollisionEventHandler BeforeCollision;
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/// <summary>
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/// Fires when two shapes collide and a contact is created between them.
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/// Note that the first fixture argument is always the fixture that the delegate is subscribed to.
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/// </summary>
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public OnCollisionEventHandler OnCollision;
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/// <summary>
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/// Fires when two shapes separate and a contact is removed between them.
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/// Note that the first fixture argument is always the fixture that the delegate is subscribed to.
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/// </summary>
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public OnSeparationEventHandler OnSeparation;
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public FixtureProxy[] Proxies;
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public int ProxyCount;
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internal Category _collidesWith;
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internal Category _collisionCategories;
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internal short _collisionGroup;
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internal Dictionary<int, bool> _collisionIgnores;
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private float _friction;
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private float _restitution;
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internal Fixture()
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{
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}
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public Fixture(Body body, Shape shape)
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: this(body, shape, null)
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{
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}
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public Fixture(Body body, Shape shape, object userData)
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{
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if (Settings.UseFPECollisionCategories)
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_collisionCategories = Category.All;
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else
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_collisionCategories = Category.Cat1;
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_collidesWith = Category.All;
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_collisionGroup = 0;
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//Fixture defaults
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Friction = 0.2f;
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Restitution = 0;
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IsSensor = false;
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Body = body;
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UserData = userData;
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#pragma warning disable 162
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if (Settings.ConserveMemory)
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Shape = shape;
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else
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Shape = shape.Clone();
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#pragma warning restore 162
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RegisterFixture();
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}
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/// <summary>
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/// Defaults to 0
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///
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/// If Settings.UseFPECollisionCategories is set to false:
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/// Collision groups allow a certain group of objects to never collide (negative)
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/// or always collide (positive). Zero means no collision group. Non-zero group
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/// filtering always wins against the mask bits.
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///
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/// If Settings.UseFPECollisionCategories is set to true:
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/// If 2 fixtures are in the same collision group, they will not collide.
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/// </summary>
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public short CollisionGroup
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{
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set
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{
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if (_collisionGroup == value)
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return;
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_collisionGroup = value;
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Refilter();
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}
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get { return _collisionGroup; }
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}
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/// <summary>
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/// Defaults to Category.All
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///
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/// The collision mask bits. This states the categories that this
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/// fixture would accept for collision.
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/// Use Settings.UseFPECollisionCategories to change the behavior.
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/// </summary>
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public Category CollidesWith
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{
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get { return _collidesWith; }
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set
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{
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if (_collidesWith == value)
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return;
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_collidesWith = value;
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Refilter();
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}
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}
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/// <summary>
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/// The collision categories this fixture is a part of.
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///
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/// If Settings.UseFPECollisionCategories is set to false:
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/// Defaults to Category.Cat1
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///
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/// If Settings.UseFPECollisionCategories is set to true:
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/// Defaults to Category.All
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/// </summary>
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public Category CollisionCategories
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{
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get { return _collisionCategories; }
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set
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{
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if (_collisionCategories == value)
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return;
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_collisionCategories = value;
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Refilter();
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}
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}
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/// <summary>
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/// Get the type of the child Shape. You can use this to down cast to the concrete Shape.
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/// </summary>
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/// <value>The type of the shape.</value>
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public ShapeType ShapeType
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{
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get { return Shape.ShapeType; }
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}
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/// <summary>
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/// Get the child Shape. You can modify the child Shape, however you should not change the
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/// number of vertices because this will crash some collision caching mechanisms.
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/// </summary>
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/// <value>The shape.</value>
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public Shape Shape { get; internal set; }
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/// <summary>
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/// Gets or sets a value indicating whether this fixture is a sensor.
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/// </summary>
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/// <value><c>true</c> if this instance is a sensor; otherwise, <c>false</c>.</value>
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public bool IsSensor { get; set; }
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/// <summary>
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/// Get the parent body of this fixture. This is null if the fixture is not attached.
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/// </summary>
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/// <value>The body.</value>
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public Body Body { get; internal set; }
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/// <summary>
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/// Set the user data. Use this to store your application specific data.
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/// </summary>
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/// <value>The user data.</value>
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public object UserData { get; set; }
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/// <summary>
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/// Get or set the coefficient of friction.
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/// </summary>
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/// <value>The friction.</value>
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public float Friction
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{
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get { return _friction; }
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set
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{
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Debug.Assert(!float.IsNaN(value));
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_friction = value;
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}
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}
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/// <summary>
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/// Get or set the coefficient of restitution.
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/// </summary>
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/// <value>The restitution.</value>
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public float Restitution
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{
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get { return _restitution; }
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set
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{
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Debug.Assert(!float.IsNaN(value));
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_restitution = value;
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}
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}
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/// <summary>
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/// Gets a unique ID for this fixture.
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/// </summary>
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/// <value>The fixture id.</value>
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public int FixtureId { get; private set; }
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#region IDisposable Members
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public bool IsDisposed { get; set; }
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public void Dispose()
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{
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if (!IsDisposed)
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{
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Body.DestroyFixture(this);
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IsDisposed = true;
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GC.SuppressFinalize(this);
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}
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}
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#endregion
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/// <summary>
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/// Restores collisions between this fixture and the provided fixture.
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/// </summary>
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/// <param name="fixture">The fixture.</param>
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public void RestoreCollisionWith(Fixture fixture)
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{
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if (_collisionIgnores == null)
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return;
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if (_collisionIgnores.ContainsKey(fixture.FixtureId))
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{
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_collisionIgnores[fixture.FixtureId] = false;
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Refilter();
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}
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}
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/// <summary>
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/// Ignores collisions between this fixture and the provided fixture.
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/// </summary>
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/// <param name="fixture">The fixture.</param>
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public void IgnoreCollisionWith(Fixture fixture)
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{
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if (_collisionIgnores == null)
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_collisionIgnores = new Dictionary<int, bool>();
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if (_collisionIgnores.ContainsKey(fixture.FixtureId))
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_collisionIgnores[fixture.FixtureId] = true;
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else
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_collisionIgnores.Add(fixture.FixtureId, true);
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Refilter();
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}
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/// <summary>
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/// Determines whether collisions are ignored between this fixture and the provided fixture.
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/// </summary>
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/// <param name="fixture">The fixture.</param>
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/// <returns>
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/// <c>true</c> if the fixture is ignored; otherwise, <c>false</c>.
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/// </returns>
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public bool IsFixtureIgnored(Fixture fixture)
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{
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if (_collisionIgnores == null)
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return false;
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if (_collisionIgnores.ContainsKey(fixture.FixtureId))
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return _collisionIgnores[fixture.FixtureId];
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return false;
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}
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/// <summary>
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/// Contacts are persistant and will keep being persistant unless they are
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/// flagged for filtering.
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/// This methods flags all contacts associated with the body for filtering.
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/// </summary>
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internal void Refilter()
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{
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// Flag associated contacts for filtering.
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ContactEdge edge = Body.ContactList;
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while (edge != null)
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{
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Contact contact = edge.Contact;
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Fixture fixtureA = contact.FixtureA;
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Fixture fixtureB = contact.FixtureB;
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if (fixtureA == this || fixtureB == this)
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{
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contact.FlagForFiltering();
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}
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edge = edge.Next;
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}
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World world = Body.World;
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if (world == null)
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{
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return;
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}
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// Touch each proxy so that new pairs may be created
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IBroadPhase broadPhase = world.ContactManager.BroadPhase;
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for (int i = 0; i < ProxyCount; ++i)
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{
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broadPhase.TouchProxy(Proxies[i].ProxyId);
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}
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}
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private void RegisterFixture()
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{
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// Reserve proxy space
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Proxies = new FixtureProxy[Shape.ChildCount];
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ProxyCount = 0;
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FixtureId = _fixtureIdCounter++;
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if ((Body.Flags & BodyFlags.Enabled) == BodyFlags.Enabled)
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{
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IBroadPhase broadPhase = Body.World.ContactManager.BroadPhase;
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CreateProxies(broadPhase, ref Body.Xf);
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}
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Body.FixtureList.Add(this);
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// Adjust mass properties if needed.
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if (Shape._density > 0.0f)
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{
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Body.ResetMassData();
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}
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// Let the world know we have a new fixture. This will cause new contacts
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// to be created at the beginning of the next time step.
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Body.World.Flags |= WorldFlags.NewFixture;
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if (Body.World.FixtureAdded != null)
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{
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Body.World.FixtureAdded(this);
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}
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}
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/// <summary>
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/// Test a point for containment in this fixture.
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/// </summary>
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/// <param name="point">A point in world coordinates.</param>
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/// <returns></returns>
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public bool TestPoint(ref Vector2 point)
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{
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return Shape.TestPoint(ref Body.Xf, ref point);
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}
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/// <summary>
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/// Cast a ray against this Shape.
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/// </summary>
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/// <param name="output">The ray-cast results.</param>
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/// <param name="input">The ray-cast input parameters.</param>
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/// <param name="childIndex">Index of the child.</param>
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/// <returns></returns>
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public bool RayCast(out RayCastOutput output, ref RayCastInput input, int childIndex)
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{
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return Shape.RayCast(out output, ref input, ref Body.Xf, childIndex);
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}
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/// <summary>
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/// Get the fixture's AABB. This AABB may be enlarge and/or stale.
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/// If you need a more accurate AABB, compute it using the Shape and
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/// the body transform.
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/// </summary>
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/// <param name="aabb">The aabb.</param>
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/// <param name="childIndex">Index of the child.</param>
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public void GetAABB(out AABB aabb, int childIndex)
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{
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Debug.Assert(0 <= childIndex && childIndex < ProxyCount);
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aabb = Proxies[childIndex].AABB;
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}
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public Fixture Clone(Body body)
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{
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Fixture fixture = new Fixture();
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fixture.Body = body;
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#pragma warning disable 162
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if (Settings.ConserveMemory)
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fixture.Shape = Shape;
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else
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fixture.Shape = Shape.Clone();
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#pragma warning restore 162
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fixture.UserData = UserData;
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fixture.Restitution = Restitution;
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fixture.Friction = Friction;
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fixture.IsSensor = IsSensor;
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fixture._collisionGroup = CollisionGroup;
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fixture._collisionCategories = CollisionCategories;
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fixture._collidesWith = CollidesWith;
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if (_collisionIgnores != null)
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{
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fixture._collisionIgnores = new Dictionary<int, bool>();
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foreach (KeyValuePair<int, bool> pair in _collisionIgnores)
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{
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fixture._collisionIgnores.Add(pair.Key, pair.Value);
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}
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}
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fixture.RegisterFixture();
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return fixture;
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}
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public Fixture DeepClone()
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{
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Fixture fix = Clone(Body.Clone());
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return fix;
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}
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internal void Destroy()
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{
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// The proxies must be destroyed before calling this.
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Debug.Assert(ProxyCount == 0);
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// Free the proxy array.
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Proxies = null;
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Shape = null;
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BeforeCollision = null;
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OnCollision = null;
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OnSeparation = null;
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AfterCollision = null;
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if (Body.World.FixtureRemoved != null)
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{
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Body.World.FixtureRemoved(this);
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}
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Body.World.FixtureAdded = null;
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Body.World.FixtureRemoved = null;
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OnSeparation = null;
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OnCollision = null;
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}
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// These support body activation/deactivation.
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internal void CreateProxies(IBroadPhase broadPhase, ref Transform xf)
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{
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Debug.Assert(ProxyCount == 0);
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// Create proxies in the broad-phase.
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ProxyCount = Shape.ChildCount;
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for (int i = 0; i < ProxyCount; ++i)
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{
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FixtureProxy proxy = new FixtureProxy();
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Shape.ComputeAABB(out proxy.AABB, ref xf, i);
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proxy.Fixture = this;
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proxy.ChildIndex = i;
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proxy.ProxyId = broadPhase.AddProxy(ref proxy);
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Proxies[i] = proxy;
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}
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}
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internal void DestroyProxies(IBroadPhase broadPhase)
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{
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// Destroy proxies in the broad-phase.
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for (int i = 0; i < ProxyCount; ++i)
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{
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broadPhase.RemoveProxy(Proxies[i].ProxyId);
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Proxies[i].ProxyId = -1;
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}
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ProxyCount = 0;
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}
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internal void Synchronize(IBroadPhase broadPhase, ref Transform transform1, ref Transform transform2)
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{
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if (ProxyCount == 0)
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{
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return;
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}
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for (int i = 0; i < ProxyCount; ++i)
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{
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FixtureProxy proxy = Proxies[i];
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// Compute an AABB that covers the swept Shape (may miss some rotation effect).
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AABB aabb1, aabb2;
|
|
Shape.ComputeAABB(out aabb1, ref transform1, proxy.ChildIndex);
|
|
Shape.ComputeAABB(out aabb2, ref transform2, proxy.ChildIndex);
|
|
|
|
proxy.AABB.Combine(ref aabb1, ref aabb2);
|
|
|
|
Vector2 displacement = transform2.Position - transform1.Position;
|
|
|
|
broadPhase.MoveProxy(proxy.ProxyId, ref proxy.AABB, displacement);
|
|
}
|
|
}
|
|
|
|
internal bool CompareTo(Fixture fixture)
|
|
{
|
|
return (
|
|
CollidesWith == fixture.CollidesWith &&
|
|
CollisionCategories == fixture.CollisionCategories &&
|
|
CollisionGroup == fixture.CollisionGroup &&
|
|
Friction == fixture.Friction &&
|
|
IsSensor == fixture.IsSensor &&
|
|
Restitution == fixture.Restitution &&
|
|
Shape.CompareTo(fixture.Shape) &&
|
|
UserData == fixture.UserData);
|
|
}
|
|
}
|
|
} |