400 lines
14 KiB
C#
400 lines
14 KiB
C#
// Copyright (c) 2017 Kastellanos Nikolaos
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/* Original source Farseer Physics Engine:
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* Copyright (c) 2014 Ian Qvist, http://farseerphysics.codeplex.com
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* Microsoft Permissive License (Ms-PL) v1.1
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*/
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/*
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* Farseer Physics Engine:
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* Copyright (c) 2012 Ian Qvist
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*
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* Original source Box2D:
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* Copyright (c) 2006-2011 Erin Catto http://www.box2d.org
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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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/// <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
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{
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private bool _isSensor;
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private float _friction;
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private float _restitution;
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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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public FixtureProxy[] Proxies { get; private set; }
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public int ProxyCount { get; private set; }
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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: This can in some cases be called multiple times, as a fixture can have multiple contacts.
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/// Note 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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internal Fixture(Category collisionCategory, Category collidesWith) // Note: This is internal because it's used by Deserialization.
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{
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_collisionCategories = collisionCategory;
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_collidesWith = collidesWith;
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_collisionGroup = 0;
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//Fixture defaults
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Friction = 0.2f;
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Restitution = 0f;
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}
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public Fixture(Shape shape, Category collisionCategory, Category collidesWith) : this(collisionCategory, collidesWith)
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{
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Shape = shape.Clone();
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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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}
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/// <summary>
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/// Defaults to 0
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///
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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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/// </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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/// </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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if (Body != null)
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{
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Body.RefreshCollidesWithMatchesBetweenFixtures();
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}
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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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/// Defaults to Category.Cat1
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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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internal 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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if (Body != null)
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{
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Body.RefreshCollisionCategoriesMatchBetweenFixtures();
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}
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}
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}
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/// <summary>
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/// Get the child Shape.
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/// </summary>
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/// <value>The shape.</value>
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public Shape Shape { get; private 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
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{
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get { return _isSensor; }
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set
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{
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if (Body != null)
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Body.Awake = true;
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_isSensor = value;
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}
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}
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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;
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/// <summary>
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/// Set the coefficient of friction. This will _not_ change the friction of
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/// existing contacts.
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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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/// Set the coefficient of restitution. This will not change the restitution of
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/// existing contacts.
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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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/// 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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private 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.FilterFlag = true;
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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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return;
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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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TouchProxies(broadPhase);
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}
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/// <summary>
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/// Touch each proxy so that new pairs may be created
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/// </summary>
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/// <param name="broadPhase"></param>
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internal void TouchProxies(IBroadPhase broadPhase)
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{
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for (int i = 0; i < ProxyCount; ++i)
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broadPhase.TouchProxy(Proxies[i].ProxyId);
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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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// 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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if (ProxyCount != 0)
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throw new InvalidOperationException("Proxies already created for this Fixture.");
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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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proxy.Fixture = this;
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proxy.ChildIndex = i;
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proxy.Body = this.Body;
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Shape.ComputeAABB(out proxy.AABB, ref xf, i);
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proxy.ProxyId = broadPhase.AddProxy(ref proxy.AABB);
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broadPhase.SetProxy(proxy.ProxyId, 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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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;
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Shape.ComputeAABB(out aabb1, ref transform1, proxy.ChildIndex);
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Shape.ComputeAABB(out aabb2, ref transform2, proxy.ChildIndex);
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proxy.AABB.Combine(ref aabb1, ref aabb2);
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Vector2 displacement = transform2.p - transform1.p;
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broadPhase.MoveProxy(proxy.ProxyId, ref proxy.AABB, displacement);
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}
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}
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/// <summary>
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/// Clones the fixture onto the specified body.
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/// </summary>
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/// <param name="body">The body you wish to clone the fixture onto.</param>
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/// <returns>The cloned fixture.</returns>
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public Fixture CloneOnto(Body body)
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{
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return CloneOnto(body, this.Shape);
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}
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/// <summary>
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/// Clones the fixture and attached shape onto the specified body.
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/// Note: This is used only by Deserialization.
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/// </summary>
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/// <param name="body">The body you wish to clone the fixture onto.</param>
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/// <returns>The cloned fixture.</returns>
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internal Fixture CloneOnto(Body body, Shape shape)
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{
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Fixture fixture = new Fixture(shape.Clone(), _collisionCategories, _collidesWith)
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{
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UserData = UserData,
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Restitution = Restitution,
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Friction = Friction,
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IsSensor = IsSensor,
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_collisionGroup = _collisionGroup
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};
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body.Add(fixture);
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return fixture;
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}
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}
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}
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