b2_body.h

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// MIT License

// Copyright (c) 2019 Erin Catto

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#ifndef B2_BODY_H
#define B2_BODY_H

#include "b2_api.h"
#include "b2_math.h"
#include "b2_shape.h"

class b2Fixture;
class b2Joint;
class b2Contact;
class b2Controller;
class b2World;
struct b2FixtureDef;
struct b2JointEdge;
struct b2ContactEdge;

enum b2BodyType
{
        b2_staticBody = 0,
        b2_kinematicBody,
        b2_dynamicBody
};

struct B2_API b2BodyDef
{
        b2BodyDef()
        {
                position.Set(0.0f, 0.0f);
                angle = 0.0f;
                linearVelocity.Set(0.0f, 0.0f);
                angularVelocity = 0.0f;
                linearDamping = 0.0f;
                angularDamping = 0.0f;
                allowSleep = true;
                awake = true;
                fixedRotation = false;
                bullet = false;
                type = b2_staticBody;
                enabled = true;
                gravityScale = 1.0f;
        }

        b2BodyType type;

        b2Vec2 position;

        float angle;

        b2Vec2 linearVelocity;

        float angularVelocity;

        float linearDamping;

        float angularDamping;

        bool allowSleep;

        bool awake;

        bool fixedRotation;

        bool bullet;

        bool enabled;

        b2BodyUserData userData;

        float gravityScale;
};

class B2_API b2Body
{
public:
        b2Fixture* CreateFixture(const b2FixtureDef* def);

        b2Fixture* CreateFixture(const b2Shape* shape, float density);

        void DestroyFixture(b2Fixture* fixture);

        void SetTransform(const b2Vec2& position, float angle);

        const b2Transform& GetTransform() const;

        const b2Vec2& GetPosition() const;

        float GetAngle() const;

        const b2Vec2& GetWorldCenter() const;

        const b2Vec2& GetLocalCenter() const;

        void SetLinearVelocity(const b2Vec2& v);

        const b2Vec2& GetLinearVelocity() const;

        void SetAngularVelocity(float omega);

        float GetAngularVelocity() const;

        void ApplyForce(const b2Vec2& force, const b2Vec2& point, bool wake);

        void ApplyForceToCenter(const b2Vec2& force, bool wake);

        void ApplyTorque(float torque, bool wake);

        void ApplyLinearImpulse(const b2Vec2& impulse, const b2Vec2& point, bool wake);

        void ApplyLinearImpulseToCenter(const b2Vec2& impulse, bool wake);

        void ApplyAngularImpulse(float impulse, bool wake);

        float GetMass() const;

        float GetInertia() const;

        void GetMassData(b2MassData* data) const;

        void SetMassData(const b2MassData* data);

        void ResetMassData();

        b2Vec2 GetWorldPoint(const b2Vec2& localPoint) const;

        b2Vec2 GetWorldVector(const b2Vec2& localVector) const;

        b2Vec2 GetLocalPoint(const b2Vec2& worldPoint) const;

        b2Vec2 GetLocalVector(const b2Vec2& worldVector) const;

        b2Vec2 GetLinearVelocityFromWorldPoint(const b2Vec2& worldPoint) const;

        b2Vec2 GetLinearVelocityFromLocalPoint(const b2Vec2& localPoint) const;

        float GetLinearDamping() const;

        void SetLinearDamping(float linearDamping);

        float GetAngularDamping() const;

        void SetAngularDamping(float angularDamping);

        float GetGravityScale() const;

        void SetGravityScale(float scale);

        void SetType(b2BodyType type);

        b2BodyType GetType() const;

        void SetBullet(bool flag);

        bool IsBullet() const;

        void SetSleepingAllowed(bool flag);

        bool IsSleepingAllowed() const;

        void SetAwake(bool flag);

        bool IsAwake() const;

        void SetEnabled(bool flag);

        bool IsEnabled() const;

        void SetFixedRotation(bool flag);

        bool IsFixedRotation() const;

        b2Fixture* GetFixtureList();
        const b2Fixture* GetFixtureList() const;

        b2JointEdge* GetJointList();
        const b2JointEdge* GetJointList() const;

        b2ContactEdge* GetContactList();
        const b2ContactEdge* GetContactList() const;

        b2Body* GetNext();
        const b2Body* GetNext() const;

        b2BodyUserData& GetUserData();

        void SetUserData(void* data);

        b2World* GetWorld();
        const b2World* GetWorld() const;

        void Dump();

private:

        friend class b2World;
        friend class b2Island;
        friend class b2ContactManager;
        friend class b2ContactSolver;
        friend class b2Contact;

        friend class b2DistanceJoint;
        friend class b2FrictionJoint;
        friend class b2GearJoint;
        friend class b2MotorJoint;
        friend class b2MouseJoint;
        friend class b2PrismaticJoint;
        friend class b2PulleyJoint;
        friend class b2RevoluteJoint;
        friend class b2RopeJoint;
        friend class b2WeldJoint;
        friend class b2WheelJoint;

        // m_flags
        enum
        {
                e_islandFlag            = 0x0001,
                e_awakeFlag                     = 0x0002,
                e_autoSleepFlag         = 0x0004,
                e_bulletFlag            = 0x0008,
                e_fixedRotationFlag     = 0x0010,
                e_enabledFlag           = 0x0020,
                e_toiFlag                       = 0x0040
        };

        b2Body(const b2BodyDef* bd, b2World* world);
        ~b2Body();

        void SynchronizeFixtures();
        void SynchronizeTransform();

        // This is used to prevent connected bodies from colliding.
        // It may lie, depending on the collideConnected flag.
        bool ShouldCollide(const b2Body* other) const;

        void Advance(float t);

        b2BodyType m_type;

        uint16 m_flags;

        int32 m_islandIndex;

        b2Transform m_xf;               // the body origin transform
        b2Sweep m_sweep;                // the swept motion for CCD

        b2Vec2 m_linearVelocity;
        float m_angularVelocity;

        b2Vec2 m_force;
        float m_torque;

        b2World* m_world;
        b2Body* m_prev;
        b2Body* m_next;

        b2Fixture* m_fixtureList;
        int32 m_fixtureCount;

        b2JointEdge* m_jointList;
        b2ContactEdge* m_contactList;

        float m_mass, m_invMass;

        // Rotational inertia about the center of mass.
        float m_I, m_invI;

        float m_linearDamping;
        float m_angularDamping;
        float m_gravityScale;

        float m_sleepTime;

        b2BodyUserData m_userData;
};

inline b2BodyType b2Body::GetType() const
{
        return m_type;
}

inline const b2Transform& b2Body::GetTransform() const
{
        return m_xf;
}

inline const b2Vec2& b2Body::GetPosition() const
{
        return m_xf.p;
}

inline float b2Body::GetAngle() const
{
        return m_sweep.a;
}

inline const b2Vec2& b2Body::GetWorldCenter() const
{
        return m_sweep.c;
}

inline const b2Vec2& b2Body::GetLocalCenter() const
{
        return m_sweep.localCenter;
}

inline void b2Body::SetLinearVelocity(const b2Vec2& v)
{
        if (m_type == b2_staticBody)
        {
                return;
        }

        if (b2Dot(v,v) > 0.0f)
        {
                SetAwake(true);
        }

        m_linearVelocity = v;
}

inline const b2Vec2& b2Body::GetLinearVelocity() const
{
        return m_linearVelocity;
}

inline void b2Body::SetAngularVelocity(float w)
{
        if (m_type == b2_staticBody)
        {
                return;
        }

        if (w * w > 0.0f)
        {
                SetAwake(true);
        }

        m_angularVelocity = w;
}

inline float b2Body::GetAngularVelocity() const
{
        return m_angularVelocity;
}

inline float b2Body::GetMass() const
{
        return m_mass;
}

inline float b2Body::GetInertia() const
{
        return m_I + m_mass * b2Dot(m_sweep.localCenter, m_sweep.localCenter);
}

inline void b2Body::GetMassData(b2MassData* data) const
{
        data->mass = m_mass;
        data->I = m_I + m_mass * b2Dot(m_sweep.localCenter, m_sweep.localCenter);
        data->center = m_sweep.localCenter;
}

inline b2Vec2 b2Body::GetWorldPoint(const b2Vec2& localPoint) const
{
        return b2Mul(m_xf, localPoint);
}

inline b2Vec2 b2Body::GetWorldVector(const b2Vec2& localVector) const
{
        return b2Mul(m_xf.q, localVector);
}

inline b2Vec2 b2Body::GetLocalPoint(const b2Vec2& worldPoint) const
{
        return b2MulT(m_xf, worldPoint);
}

inline b2Vec2 b2Body::GetLocalVector(const b2Vec2& worldVector) const
{
        return b2MulT(m_xf.q, worldVector);
}

inline b2Vec2 b2Body::GetLinearVelocityFromWorldPoint(const b2Vec2& worldPoint) const
{
        return m_linearVelocity + b2Cross(m_angularVelocity, worldPoint - m_sweep.c);
}

inline b2Vec2 b2Body::GetLinearVelocityFromLocalPoint(const b2Vec2& localPoint) const
{
        return GetLinearVelocityFromWorldPoint(GetWorldPoint(localPoint));
}

inline float b2Body::GetLinearDamping() const
{
        return m_linearDamping;
}

inline void b2Body::SetLinearDamping(float linearDamping)
{
        m_linearDamping = linearDamping;
}

inline float b2Body::GetAngularDamping() const
{
        return m_angularDamping;
}

inline void b2Body::SetAngularDamping(float angularDamping)
{
        m_angularDamping = angularDamping;
}

inline float b2Body::GetGravityScale() const
{
        return m_gravityScale;
}

inline void b2Body::SetGravityScale(float scale)
{
        m_gravityScale = scale;
}

inline void b2Body::SetBullet(bool flag)
{
        if (flag)
        {
                m_flags |= e_bulletFlag;
        }
        else
        {
                m_flags &= ~e_bulletFlag;
        }
}

inline bool b2Body::IsBullet() const
{
        return (m_flags & e_bulletFlag) == e_bulletFlag;
}

inline void b2Body::SetAwake(bool flag)
{
        if (m_type == b2_staticBody)
        {
                return;
        }

        if (flag)
        {
                m_flags |= e_awakeFlag;
                m_sleepTime = 0.0f;
        }
        else
        {
                m_flags &= ~e_awakeFlag;
                m_sleepTime = 0.0f;
                m_linearVelocity.SetZero();
                m_angularVelocity = 0.0f;
                m_force.SetZero();
                m_torque = 0.0f;
        }
}

inline bool b2Body::IsAwake() const
{
        return (m_flags & e_awakeFlag) == e_awakeFlag;
}

inline bool b2Body::IsEnabled() const
{
        return (m_flags & e_enabledFlag) == e_enabledFlag;
}

inline bool b2Body::IsFixedRotation() const
{
        return (m_flags & e_fixedRotationFlag) == e_fixedRotationFlag;
}

inline void b2Body::SetSleepingAllowed(bool flag)
{
        if (flag)
        {
                m_flags |= e_autoSleepFlag;
        }
        else
        {
                m_flags &= ~e_autoSleepFlag;
                SetAwake(true);
        }
}

inline bool b2Body::IsSleepingAllowed() const
{
        return (m_flags & e_autoSleepFlag) == e_autoSleepFlag;
}

inline b2Fixture* b2Body::GetFixtureList()
{
        return m_fixtureList;
}

inline const b2Fixture* b2Body::GetFixtureList() const
{
        return m_fixtureList;
}

inline b2JointEdge* b2Body::GetJointList()
{
        return m_jointList;
}

inline const b2JointEdge* b2Body::GetJointList() const
{
        return m_jointList;
}

inline b2ContactEdge* b2Body::GetContactList()
{
        return m_contactList;
}

inline const b2ContactEdge* b2Body::GetContactList() const
{
        return m_contactList;
}

inline b2Body* b2Body::GetNext()
{
        return m_next;
}

inline const b2Body* b2Body::GetNext() const
{
        return m_next;
}

inline b2BodyUserData& b2Body::GetUserData()
{
        return m_userData;
}

inline void b2Body::ApplyForce(const b2Vec2& force, const b2Vec2& point, bool wake)
{
        if (m_type != b2_dynamicBody)
        {
                return;
        }

        if (wake && (m_flags & e_awakeFlag) == 0)
        {
                SetAwake(true);
        }

        // Don't accumulate a force if the body is sleeping.
        if (m_flags & e_awakeFlag)
        {
                m_force += force;
                m_torque += b2Cross(point - m_sweep.c, force);
        }
}

inline void b2Body::ApplyForceToCenter(const b2Vec2& force, bool wake)
{
        if (m_type != b2_dynamicBody)
        {
                return;
        }

        if (wake && (m_flags & e_awakeFlag) == 0)
        {
                SetAwake(true);
        }

        // Don't accumulate a force if the body is sleeping
        if (m_flags & e_awakeFlag)
        {
                m_force += force;
        }
}

inline void b2Body::ApplyTorque(float torque, bool wake)
{
        if (m_type != b2_dynamicBody)
        {
                return;
        }

        if (wake && (m_flags & e_awakeFlag) == 0)
        {
                SetAwake(true);
        }

        // Don't accumulate a force if the body is sleeping
        if (m_flags & e_awakeFlag)
        {
                m_torque += torque;
        }
}

inline void b2Body::ApplyLinearImpulse(const b2Vec2& impulse, const b2Vec2& point, bool wake)
{
        if (m_type != b2_dynamicBody)
        {
                return;
        }

        if (wake && (m_flags & e_awakeFlag) == 0)
        {
                SetAwake(true);
        }

        // Don't accumulate velocity if the body is sleeping
        if (m_flags & e_awakeFlag)
        {
                m_linearVelocity += m_invMass * impulse;
                m_angularVelocity += m_invI * b2Cross(point - m_sweep.c, impulse);
        }
}

inline void b2Body::ApplyLinearImpulseToCenter(const b2Vec2& impulse, bool wake)
{
        if (m_type != b2_dynamicBody)
        {
                return;
        }

        if (wake && (m_flags & e_awakeFlag) == 0)
        {
                SetAwake(true);
        }

        // Don't accumulate velocity if the body is sleeping
        if (m_flags & e_awakeFlag)
        {
                m_linearVelocity += m_invMass * impulse;
        }
}

inline void b2Body::ApplyAngularImpulse(float impulse, bool wake)
{
        if (m_type != b2_dynamicBody)
        {
                return;
        }

        if (wake && (m_flags & e_awakeFlag) == 0)
        {
                SetAwake(true);
        }

        // Don't accumulate velocity if the body is sleeping
        if (m_flags & e_awakeFlag)
        {
                m_angularVelocity += m_invI * impulse;
        }
}

inline void b2Body::SynchronizeTransform()
{
        m_xf.q.Set(m_sweep.a);
        m_xf.p = m_sweep.c - b2Mul(m_xf.q, m_sweep.localCenter);
}

inline void b2Body::Advance(float alpha)
{
        // Advance to the new safe time. This doesn't sync the broad-phase.
        m_sweep.Advance(alpha);
        m_sweep.c = m_sweep.c0;
        m_sweep.a = m_sweep.a0;
        m_xf.q.Set(m_sweep.a);
        m_xf.p = m_sweep.c - b2Mul(m_xf.q, m_sweep.localCenter);
}

inline b2World* b2Body::GetWorld()
{
        return m_world;
}

inline const b2World* b2Body::GetWorld() const
{
        return m_world;
}

#endif