b2WorldCallbacks.h
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- /*
- * Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com
- *
- * 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;
- struct b2ContactPoint;
- struct b2ContactResult;
- struct b2Manifold;
- /// 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;
- };
- /// 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);
- };
- /// 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];
- };
- /// 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); }
- /// 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;
- };
- /// 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;
- };
- /// Color for debug drawing. Each value has the range [0,1].
- struct b2Color
- {
- b2Color() {}
- b2Color(float32 r, float32 g, float32 b) : r(r), g(g), b(b) {}
- void Set(float32 ri, float32 gi, float32 bi) { r = ri; g = gi; b = bi; }
- float32 r, g, b;
- };
- /// Implement and register this class with a b2World to provide debug drawing of physics
- /// entities in your game.
- class b2DebugDraw
- {
- public:
- b2DebugDraw();
- virtual ~b2DebugDraw() {}
- enum
- {
- e_shapeBit = 0x0001, ///< draw shapes
- e_jointBit = 0x0002, ///< draw joint connections
- e_aabbBit = 0x0004, ///< draw axis aligned bounding boxes
- e_pairBit = 0x0008, ///< draw broad-phase pairs
- e_centerOfMassBit = 0x0010, ///< draw center of mass frame
- };
- /// Set the drawing flags.
- void SetFlags(uint32 flags);
- /// Get the drawing flags.
- uint32 GetFlags() const;
-
- /// Append flags to the current flags.
- void AppendFlags(uint32 flags);
- /// Clear flags from the current flags.
- void ClearFlags(uint32 flags);
- /// Draw a closed polygon provided in CCW order.
- virtual void DrawPolygon(const b2Vec2* vertices, int32 vertexCount, const b2Color& color) = 0;
- /// Draw a solid closed polygon provided in CCW order.
- virtual void DrawSolidPolygon(const b2Vec2* vertices, int32 vertexCount, const b2Color& color) = 0;
- /// Draw a circle.
- virtual void DrawCircle(const b2Vec2& center, float32 radius, const b2Color& color) = 0;
-
- /// Draw a solid circle.
- virtual void DrawSolidCircle(const b2Vec2& center, float32 radius, const b2Vec2& axis, const b2Color& color) = 0;
-
- /// Draw a line segment.
- virtual void DrawSegment(const b2Vec2& p1, const b2Vec2& p2, const b2Color& color) = 0;
- /// Draw a transform. Choose your own length scale.
- /// @param xf a transform.
- virtual void DrawTransform(const b2Transform& xf) = 0;
- protected:
- uint32 m_drawFlags;
- };
- #endif