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deps/include/Box2D/Dynamics/b2WorldCallbacks.h

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+/*
+* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
+* Copyright (c) 2013 Google, Inc.
+*
+* 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.
+*/
+
+#ifndef B2_WORLD_CALLBACKS_H
+#define B2_WORLD_CALLBACKS_H
+
+#include <Box2D/Common/b2Settings.h>
+
+struct b2Vec2;
+struct b2Transform;
+class b2Fixture;
+class b2Body;
+class b2Joint;
+class b2Contact;
+class b2ParticleSystem;
+struct b2ContactResult;
+struct b2Manifold;
+class b2ParticleGroup;
+struct b2ParticleBodyContact;
+struct b2ParticleContact;
+
+/// Joints and fixtures are destroyed when their associated
+/// body is destroyed. Implement this listener so that you
+/// may nullify references to these joints and shapes.
+class b2DestructionListener
+{
+public:
+	virtual ~b2DestructionListener() {}
+
+	/// Called when any joint is about to be destroyed due
+	/// to the destruction of one of its attached bodies.
+	virtual void SayGoodbye(b2Joint* joint) = 0;
+
+	/// Called when any fixture is about to be destroyed due
+	/// to the destruction of its parent body.
+	virtual void SayGoodbye(b2Fixture* fixture) = 0;
+
+	/// Called when any particle group is about to be destroyed.
+	virtual void SayGoodbye(b2ParticleGroup* group)
+	{
+		B2_NOT_USED(group);
+	}
+
+	/// Called when a particle is about to be destroyed.
+	/// The index can be used in conjunction with
+	/// b2ParticleSystem::GetUserDataBuffer() or
+	/// b2ParticleSystem::GetParticleHandleFromIndex() to determine which
+	/// particle has been destroyed.
+	virtual void SayGoodbye(b2ParticleSystem* particleSystem, int32 index)
+	{
+		B2_NOT_USED(particleSystem);
+		B2_NOT_USED(index);
+	}
+};
+
+/// Implement this class to provide collision filtering. In other words, you can implement
+/// this class if you want finer control over contact creation.
+class b2ContactFilter
+{
+public:
+	virtual ~b2ContactFilter() {}
+
+	/// Return true if contact calculations should be performed between these two shapes.
+	/// @warning for performance reasons this is only called when the AABBs begin to overlap.
+	virtual bool ShouldCollide(b2Fixture* fixtureA, b2Fixture* fixtureB);
+
+	/// Return true if contact calculations should be performed between a
+	/// fixture and particle.  This is only called if the
+	/// b2_fixtureContactListenerParticle flag is set on the particle.
+	virtual bool ShouldCollide(b2Fixture* fixture,
+							   b2ParticleSystem* particleSystem,
+							   int32 particleIndex)
+	{
+		B2_NOT_USED(fixture);
+		B2_NOT_USED(particleIndex);
+		B2_NOT_USED(particleSystem);
+		return true;
+	}
+
+	/// Return true if contact calculations should be performed between two
+	/// particles.  This is only called if the
+	/// b2_particleContactListenerParticle flag is set on the particle.
+	virtual bool ShouldCollide(b2ParticleSystem* particleSystem,
+							   int32 particleIndexA, int32 particleIndexB)
+	{
+		B2_NOT_USED(particleSystem);
+		B2_NOT_USED(particleIndexA);
+		B2_NOT_USED(particleIndexB);
+		return true;
+	}
+};
+
+/// Contact impulses for reporting. Impulses are used instead of forces because
+/// sub-step forces may approach infinity for rigid body collisions. These
+/// match up one-to-one with the contact points in b2Manifold.
+struct b2ContactImpulse
+{
+	float32 normalImpulses[b2_maxManifoldPoints];
+	float32 tangentImpulses[b2_maxManifoldPoints];
+	int32 count;
+};
+
+/// Implement this class to get contact information. You can use these results for
+/// things like sounds and game logic. You can also get contact results by
+/// traversing the contact lists after the time step. However, you might miss
+/// some contacts because continuous physics leads to sub-stepping.
+/// Additionally you may receive multiple callbacks for the same contact in a
+/// single time step.
+/// You should strive to make your callbacks efficient because there may be
+/// many callbacks per time step.
+/// @warning You cannot create/destroy Box2D entities inside these callbacks.
+class b2ContactListener
+{
+public:
+	virtual ~b2ContactListener() {}
+
+	/// Called when two fixtures begin to touch.
+	virtual void BeginContact(b2Contact* contact) { B2_NOT_USED(contact); }
+
+	/// Called when two fixtures cease to touch.
+	virtual void EndContact(b2Contact* contact) { B2_NOT_USED(contact); }
+
+	/// Called when a fixture and particle start touching if the
+	/// b2_fixtureContactFilterParticle flag is set on the particle.
+	virtual void BeginContact(b2ParticleSystem* particleSystem,
+							  b2ParticleBodyContact* particleBodyContact)
+	{
+		B2_NOT_USED(particleSystem);
+		B2_NOT_USED(particleBodyContact);
+	}
+
+	/// Called when a fixture and particle stop touching if the
+	/// b2_fixtureContactFilterParticle flag is set on the particle.
+	virtual void EndContact(b2Fixture* fixture,
+							b2ParticleSystem* particleSystem, int32 index)
+	{
+		B2_NOT_USED(fixture);
+		B2_NOT_USED(particleSystem);
+		B2_NOT_USED(index);
+	}
+
+	/// Called when two particles start touching if
+	/// b2_particleContactFilterParticle flag is set on either particle.
+	virtual void BeginContact(b2ParticleSystem* particleSystem,
+							  b2ParticleContact* particleContact)
+	{
+		B2_NOT_USED(particleSystem);
+		B2_NOT_USED(particleContact);
+	}
+
+	/// Called when two particles start touching if
+	/// b2_particleContactFilterParticle flag is set on either particle.
+	virtual void EndContact(b2ParticleSystem* particleSystem,
+							int32 indexA, int32 indexB)
+	{
+		B2_NOT_USED(particleSystem);
+		B2_NOT_USED(indexA);
+		B2_NOT_USED(indexB);
+	}
+
+	/// This is called after a contact is updated. This allows you to inspect a
+	/// contact before it goes to the solver. If you are careful, you can modify the
+	/// contact manifold (e.g. disable contact).
+	/// A copy of the old manifold is provided so that you can detect changes.
+	/// Note: this is called only for awake bodies.
+	/// Note: this is called even when the number of contact points is zero.
+	/// Note: this is not called for sensors.
+	/// Note: if you set the number of contact points to zero, you will not
+	/// get an EndContact callback. However, you may get a BeginContact callback
+	/// the next step.
+	virtual void PreSolve(b2Contact* contact, const b2Manifold* oldManifold)
+	{
+		B2_NOT_USED(contact);
+		B2_NOT_USED(oldManifold);
+	}
+
+	/// This lets you inspect a contact after the solver is finished. This is useful
+	/// for inspecting impulses.
+	/// Note: the contact manifold does not include time of impact impulses, which can be
+	/// arbitrarily large if the sub-step is small. Hence the impulse is provided explicitly
+	/// in a separate data structure.
+	/// Note: this is only called for contacts that are touching, solid, and awake.
+	virtual void PostSolve(b2Contact* contact, const b2ContactImpulse* impulse)
+	{
+		B2_NOT_USED(contact);
+		B2_NOT_USED(impulse);
+	}
+};
+
+/// Callback class for AABB queries.
+/// See b2World::Query
+class b2QueryCallback
+{
+public:
+	virtual ~b2QueryCallback() {}
+
+	/// Called for each fixture found in the query AABB.
+	/// @return false to terminate the query.
+	virtual bool ReportFixture(b2Fixture* fixture) = 0;
+
+	/// Called for each particle found in the query AABB.
+	/// @return false to terminate the query.
+	virtual bool ReportParticle(const b2ParticleSystem* particleSystem,
+								int32 index)
+	{
+		B2_NOT_USED(particleSystem);
+		B2_NOT_USED(index);
+		return false;
+	}
+
+	/// Cull an entire particle system from b2World::QueryAABB. Ignored for
+	/// b2ParticleSystem::QueryAABB.
+	/// @return true if you want to include particleSystem in the AABB query,
+	/// or false to cull particleSystem from the AABB query.
+	virtual bool ShouldQueryParticleSystem(
+		const b2ParticleSystem* particleSystem)
+	{
+		B2_NOT_USED(particleSystem);
+		return true;
+	}
+};
+
+/// Callback class for ray casts.
+/// See b2World::RayCast
+class b2RayCastCallback
+{
+public:
+	virtual ~b2RayCastCallback() {}
+
+	/// Called for each fixture found in the query. You control how the ray cast
+	/// proceeds by returning a float:
+	/// return -1: ignore this fixture and continue
+	/// return 0: terminate the ray cast
+	/// return fraction: clip the ray to this point
+	/// return 1: don't clip the ray and continue
+	/// @param fixture the fixture hit by the ray
+	/// @param point the point of initial intersection
+	/// @param normal the normal vector at the point of intersection
+	/// @return -1 to filter, 0 to terminate, fraction to clip the ray for
+	/// closest hit, 1 to continue
+	virtual float32 ReportFixture(	b2Fixture* fixture, const b2Vec2& point,
+									const b2Vec2& normal, float32 fraction) = 0;
+
+	/// Called for each particle found in the query. You control how the ray
+	/// cast proceeds by returning a float:
+	/// return <=0: ignore the remaining particles in this particle system
+	/// return fraction: ignore particles that are 'fraction' percent farther
+	///   along the line from 'point1' to 'point2'. Note that 'point1' and
+	///   'point2' are parameters to b2World::RayCast.
+	/// @param particleSystem the particle system containing the particle
+	/// @param index the index of the particle in particleSystem
+	/// @param point the point of intersection bt the ray and the particle
+	/// @param normal the normal vector at the point of intersection
+	/// @param fraction percent (0.0~1.0) from 'point0' to 'point1' along the
+	///   ray. Note that 'point1' and 'point2' are parameters to
+	///   b2World::RayCast.
+	/// @return <=0 to ignore rest of particle system, fraction to ignore
+	/// particles that are farther away.
+	virtual float32 ReportParticle(const b2ParticleSystem* particleSystem,
+								   int32 index, const b2Vec2& point,
+								   const b2Vec2& normal, float32 fraction)
+	{
+		B2_NOT_USED(particleSystem);
+		B2_NOT_USED(index);
+		B2_NOT_USED(&point);
+		B2_NOT_USED(&normal);
+		B2_NOT_USED(fraction);
+		return 0;
+	}
+
+	/// Cull an entire particle system from b2World::RayCast. Ignored in
+	/// b2ParticleSystem::RayCast.
+	/// @return true if you want to include particleSystem in the RayCast, or
+	/// false to cull particleSystem from the RayCast.
+	virtual bool ShouldQueryParticleSystem(
+		const b2ParticleSystem* particleSystem)
+	{
+		B2_NOT_USED(particleSystem);
+		return true;
+	}
+};
+
+#endif