/**
 * *****************************************************************************
 * Copyright (c) 2013, Daniel Murphy
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * 	* Redistributions of source code must retain the above copyright notice,
 * 	  this list of conditions and the following disclaimer.
 * 	* Redistributions in binary form must reproduce the above copyright notice,
 * 	  this list of conditions and the following disclaimer in the documentation
 * 	  and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *****************************************************************************
 */
package org.jbox2d.dynamics;

import org.jbox2d.collision.broadphase.BroadPhase;
import org.jbox2d.collision.shapes.MassData;
import org.jbox2d.collision.shapes.Shape;
import org.jbox2d.common.MathUtils;
import org.jbox2d.common.Rot;
import org.jbox2d.common.Sweep;
import org.jbox2d.common.Transform;
import org.jbox2d.common.Vec2;
import org.jbox2d.dynamics.contacts.Contact;
import org.jbox2d.dynamics.contacts.ContactEdge;
import org.jbox2d.dynamics.joints.JointEdge;

/**
 * A rigid body. These are created via World.createBody.
 *
 * @author Daniel Murphy
 */
public class Body {

    public static final int E_ISLAND_FLAG = 0x0001;
    public static final int E_AWAKE_FLAG = 0x0002;
    public static final int E_AUTO_SLEEP_FLAG = 0x0004;
    public static final int E_BULLET_FLAG = 0x0008;
    public static final int E_FIXED_ROTATION_FLAG = 0x0010;
    public static final int E_ACTIVE_FLAG = 0x0020;
    public static final int E_TO_I_FLAG = 0x0040;

    public BodyType m_type;

    public int m_flags;

    public int m_islandIndex;

    /**
     * The body origin transform.
     */
    public final Transform m_xf = new Transform();
    /**
     * The previous transform for particle simulation
     */
    public final Transform m_xf0 = new Transform();

    /**
     * The swept motion for CCD
     */
    public final Sweep m_sweep = new Sweep();

    public final Vec2 m_linearVelocity = new Vec2();
    public float m_angularVelocity = 0;

    public final Vec2 m_force = new Vec2();
    public float m_torque = 0;

    public World m_world;
    public Body m_prev;
    public Body m_next;

    public Fixture m_fixtureList;
    public int m_fixtureCount;

    public JointEdge m_jointList;
    public ContactEdge m_contactList;

    public float m_mass, m_invMass;

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

    public float m_linearDamping;
    public float m_angularDamping;
    public float m_gravityScale;

    public float m_sleepTime;

    public Object m_userData;

    public Body(final BodyDef bd, World world) {
        assert (bd.position.isValid());
        assert (bd.linearVelocity.isValid());
        assert (bd.gravityScale >= 0.0f);
        assert (bd.angularDamping >= 0.0f);
        assert (bd.linearDamping >= 0.0f);

        m_flags = 0;

        if (bd.bullet) {
            m_flags |= E_BULLET_FLAG;
        }
        if (bd.fixedRotation) {
            m_flags |= E_FIXED_ROTATION_FLAG;
        }
        if (bd.allowSleep) {
            m_flags |= E_AUTO_SLEEP_FLAG;
        }
        if (bd.awake) {
            m_flags |= E_AWAKE_FLAG;
        }
        if (bd.active) {
            m_flags |= E_ACTIVE_FLAG;
        }

        m_world = world;

        m_xf.p.set(bd.position);
        m_xf.q.set(bd.angle);

        m_sweep.localCenter.setZero();
        m_sweep.c0.set(m_xf.p);
        m_sweep.c.set(m_xf.p);
        m_sweep.a0 = bd.angle;
        m_sweep.a = bd.angle;
        m_sweep.alpha0 = 0.0f;

        m_jointList = null;
        m_contactList = null;
        m_prev = null;
        m_next = null;

        m_linearVelocity.set(bd.linearVelocity);
        m_angularVelocity = bd.angularVelocity;

        m_linearDamping = bd.linearDamping;
        m_angularDamping = bd.angularDamping;
        m_gravityScale = bd.gravityScale;

        m_force.setZero();
        m_torque = 0.0f;

        m_sleepTime = 0.0f;

        m_type = bd.type;

        if (m_type == BodyType.DYNAMIC) {
            m_mass = 1f;
            m_invMass = 1f;
        } else {
            m_mass = 0f;
            m_invMass = 0f;
        }

        m_I = 0.0f;
        m_invI = 0.0f;

        m_userData = bd.userData;

        m_fixtureList = null;
        m_fixtureCount = 0;
    }

    /**
     * Creates a fixture and attach it to this body. Use this function if you
     * need to set some fixture parameters, like friction. Otherwise you can
     * create the fixture directly from a shape. If the density is non-zero,
     * this function automatically updates the mass of the body. Contacts are
     * not created until the next time step.
     *
     * @param def the fixture definition.
     * @return
     * @warning This function is locked during callbacks.
     */
    public final Fixture createFixture(FixtureDef def) {
        assert (m_world.isLocked() == false);

        if (m_world.isLocked() == true) {
            return null;
        }

        Fixture fixture = new Fixture();
        fixture.create(this, def);

        if ((m_flags & E_ACTIVE_FLAG) == E_ACTIVE_FLAG) {
            BroadPhase broadPhase = m_world.m_contactManager.m_broadPhase;
            fixture.createProxies(broadPhase, m_xf);
        }

        fixture.m_next = m_fixtureList;
        m_fixtureList = fixture;
        ++m_fixtureCount;

        fixture.m_body = this;

        // Adjust mass properties if needed.
        if (fixture.m_density > 0.0f) {
            resetMassData();
        }

        // Let the world know we have a new fixture. This will cause new contacts
        // to be created at the beginning of the next time step.
        m_world.m_flags |= World.NEW_FIXTURE;

        return fixture;
    }

    private final FixtureDef fixDef = new FixtureDef();

    /**
     * Creates a fixture from a shape and attach it to this body. This is a
     * convenience function. Use FixtureDef if you need to set parameters like
     * friction, restitution, user data, or filtering. If the density is
     * non-zero, this function automatically updates the mass of the body.
     *
     * @param shape the shape to be cloned.
     * @param density the shape density (set to zero for static bodies).
     * @return
     * @warning This function is locked during callbacks.
     */
    public final Fixture createFixture(Shape shape, float density) {
        fixDef.shape = shape;
        fixDef.density = density;

        return createFixture(fixDef);
    }

    /**
     * Destroy a fixture. This removes the fixture from the broad-phase and
     * destroys all contacts associated with this fixture. This will
     * automatically adjust the mass of the body if the body is dynamic and the
     * fixture has positive density. All fixtures attached to a body are
     * implicitly destroyed when the body is destroyed.
     *
     * @param fixture the fixture to be removed.
     * @warning This function is locked during callbacks.
     */
    public final void destroyFixture(Fixture fixture) {
        assert (m_world.isLocked() == false);
        if (m_world.isLocked() == true) {
            return;
        }

        assert (fixture.m_body == this);

        // Remove the fixture from this body's singly linked list.
        assert (m_fixtureCount > 0);
        Fixture node = m_fixtureList;
        Fixture last = null; // java change
        boolean found = false;
        while (node != null) {
            if (node == fixture) {
                node = fixture.m_next;
                found = true;
                break;
            }
            last = node;
            node = node.m_next;
        }

        // You tried to remove a shape that is not attached to this body.
        assert (found);

        // java change, remove it from the list
        if (last == null) {
            m_fixtureList = fixture.m_next;
        } else {
            last.m_next = fixture.m_next;
        }

        // Destroy any contacts associated with the fixture.
        ContactEdge edge = m_contactList;
        while (edge != null) {
            Contact c = edge.contact;
            edge = edge.next;

            Fixture fixtureA = c.getFixtureA();
            Fixture fixtureB = c.getFixtureB();

            if (fixture == fixtureA || fixture == fixtureB) {
                // This destroys the contact and removes it from
                // this body's contact list.
                m_world.m_contactManager.destroy(c);
            }
        }

        if ((m_flags & E_ACTIVE_FLAG) == E_ACTIVE_FLAG) {
            BroadPhase broadPhase = m_world.m_contactManager.m_broadPhase;
            fixture.destroyProxies(broadPhase);
        }

        fixture.destroy();
        fixture.m_body = null;
        fixture.m_next = null;
        fixture = null;

        --m_fixtureCount;

        // Reset the mass data.
        resetMassData();
    }

    /**
     * Set the position of the body's origin and rotation. This breaks any
     * contacts and wakes the other bodies. Manipulating a body's transform may
     * cause non-physical behavior. Note: contacts are updated on the next call
     * to World.step().
     *
     * @param position the world position of the body's local origin.
     * @param angle the world rotation in radians.
     */
    public final void setTransform(Vec2 position, float angle) {
        assert (m_world.isLocked() == false);
        if (m_world.isLocked() == true) {
            return;
        }

        m_xf.q.set(angle);
        m_xf.p.set(position);

        // m_sweep.c0 = m_sweep.c = Mul(m_xf, m_sweep.localCenter);
        Transform.mulToOutUnsafe(m_xf, m_sweep.localCenter, m_sweep.c);
        m_sweep.a = angle;

        m_sweep.c0.set(m_sweep.c);
        m_sweep.a0 = m_sweep.a;

        BroadPhase broadPhase = m_world.m_contactManager.m_broadPhase;
        for (Fixture f = m_fixtureList; f != null; f = f.m_next) {
            f.synchronize(broadPhase, m_xf, m_xf);
        }
    }

    /**
     * Get the body transform for the body's origin.
     *
     * @return the world transform of the body's origin.
     */
    public final Transform getTransform() {
        return m_xf;
    }

    /**
     * Get the world body origin position. Do not modify.
     *
     * @return the world position of the body's origin.
     */
    public final Vec2 getPosition() {
        return m_xf.p;
    }

    /**
     * Get the angle in radians.
     *
     * @return the current world rotation angle in radians.
     */
    public final float getAngle() {
        return m_sweep.a;
    }

    /**
     * Get the world position of the center of mass. Do not modify.
     * @return 
     */
    public final Vec2 getWorldCenter() {
        return m_sweep.c;
    }

    /**
     * Get the local position of the center of mass. Do not modify.
     * @return 
     */
    public final Vec2 getLocalCenter() {
        return m_sweep.localCenter;
    }

    /**
     * Set the linear velocity of the center of mass.
     *
     * @param v the new linear velocity of the center of mass.
     */
    public final void setLinearVelocity(Vec2 v) {
        if (m_type == BodyType.STATIC) {
            return;
        }

        if (Vec2.dot(v, v) > 0.0f) {
            setAwake(true);
        }

        m_linearVelocity.set(v);
    }

    /**
     * Get the linear velocity of the center of mass. Do not modify, instead use
     * {@link #setLinearVelocity(Vec2)}.
     *
     * @return the linear velocity of the center of mass.
     */
    public final Vec2 getLinearVelocity() {
        return m_linearVelocity;
    }

    /**
     * Set the angular velocity.
     *
     * @param w the new angular velocity in radians/second.
     */
    public final void setAngularVelocity(float w) {
        if (m_type == BodyType.STATIC) {
            return;
        }

        if (w * w > 0f) {
            setAwake(true);
        }

        m_angularVelocity = w;
    }

    /**
     * Get the angular velocity.
     *
     * @return the angular velocity in radians/second.
     */
    public final float getAngularVelocity() {
        return m_angularVelocity;
    }

    /**
     * Get the gravity scale of the body.
     *
     * @return
     */
    public float getGravityScale() {
        return m_gravityScale;
    }

    /**
     * Set the gravity scale of the body.
     *
     * @param gravityScale
     */
    public void setGravityScale(float gravityScale) {
        this.m_gravityScale = gravityScale;
    }

    /**
     * Apply a force at a world point. If the force is not applied at the center
     * of mass, it will generate a torque and affect the angular velocity. This
     * wakes up the body.
     *
     * @param force the world force vector, usually in Newtons (N).
     * @param point the world position of the point of application.
     */
    public final void applyForce(Vec2 force, Vec2 point) {
        if (m_type != BodyType.DYNAMIC) {
            return;
        }

        if (isAwake() == false) {
            setAwake(true);
        }

        // m_force.addLocal(force);
        // Vec2 temp = tltemp.get();
        // temp.set(point).subLocal(m_sweep.c);
        // m_torque += Vec2.cross(temp, force);
        m_force.x += force.x;
        m_force.y += force.y;

        m_torque += (point.x - m_sweep.c.x) * force.y - (point.y - m_sweep.c.y) * force.x;
    }

    /**
     * Apply a force to the center of mass. This wakes up the body.
     *
     * @param force the world force vector, usually in Newtons (N).
     */
    public final void applyForceToCenter(Vec2 force) {
        if (m_type != BodyType.DYNAMIC) {
            return;
        }

        if (isAwake() == false) {
            setAwake(true);
        }

        m_force.x += force.x;
        m_force.y += force.y;
    }

    /**
     * Apply a torque. This affects the angular velocity without affecting the
     * linear velocity of the center of mass. This wakes up the body.
     *
     * @param torque about the z-axis (out of the screen), usually in N-m.
     */
    public final void applyTorque(float torque) {
        if (m_type != BodyType.DYNAMIC) {
            return;
        }

        if (isAwake() == false) {
            setAwake(true);
        }

        m_torque += torque;
    }

    /**
     * Apply an impulse at a point. This immediately modifies the velocity. It
     * also modifies the angular velocity if the point of application is not at
     * the center of mass. This wakes up the body if 'wake' is set to true. If
     * the body is sleeping and 'wake' is false, then there is no effect.
     *
     * @param impulse the world impulse vector, usually in N-seconds or kg-m/s.
     * @param point the world position of the point of application.
     * @param wake also wake up the body
     */
    public final void applyLinearImpulse(Vec2 impulse, Vec2 point, boolean wake) {
        if (m_type != BodyType.DYNAMIC) {
            return;
        }

        if (!isAwake()) {
            if (wake) {
                setAwake(true);
            } else {
                return;
            }
        }

        m_linearVelocity.x += impulse.x * m_invMass;
        m_linearVelocity.y += impulse.y * m_invMass;

        m_angularVelocity
                += m_invI * ((point.x - m_sweep.c.x) * impulse.y - (point.y - m_sweep.c.y) * impulse.x);
    }

    /**
     * Apply an angular impulse.
     *
     * @param impulse the angular impulse in units of kg*m*m/s
     */
    public void applyAngularImpulse(float impulse) {
        if (m_type != BodyType.DYNAMIC) {
            return;
        }

        if (isAwake() == false) {
            setAwake(true);
        }
        m_angularVelocity += m_invI * impulse;
    }

    /**
     * Get the total mass of the body.
     *
     * @return the mass, usually in kilograms (kg).
     */
    public final float getMass() {
        return m_mass;
    }

    /**
     * Get the central rotational inertia of the body.
     *
     * @return the rotational inertia, usually in kg-m^2.
     */
    public final float getInertia() {
        return m_I
                + m_mass
                * (m_sweep.localCenter.x * m_sweep.localCenter.x + m_sweep.localCenter.y
                * m_sweep.localCenter.y);
    }

    /**
     * Get the mass data of the body. The rotational inertia is relative to the
     * center of mass.
     *
     * @param data
     */
    public final void getMassData(MassData data) {
        // data.mass = m_mass;
        // data.I = m_I + m_mass * Vec2.dot(m_sweep.localCenter, m_sweep.localCenter);
        // data.center.set(m_sweep.localCenter);

        data.mass = m_mass;
        data.I
                = m_I
                + m_mass
                * (m_sweep.localCenter.x * m_sweep.localCenter.x + m_sweep.localCenter.y
                * m_sweep.localCenter.y);
        data.center.x = m_sweep.localCenter.x;
        data.center.y = m_sweep.localCenter.y;
    }

    /**
     * Set the mass properties to override the mass properties of the fixtures.
     * Note that this changes the center of mass position. Note that creating or
     * destroying fixtures can also alter the mass. This function has no effect
     * if the body isn't dynamic.
     *
     * @param massData the mass properties.
     */
    public final void setMassData(MassData massData) {
        // TODO_ERIN adjust linear velocity and torque to account for movement of center.
        assert (m_world.isLocked() == false);
        if (m_world.isLocked() == true) {
            return;
        }

        if (m_type != BodyType.DYNAMIC) {
            return;
        }

        m_invMass = 0.0f;
        m_I = 0.0f;
        m_invI = 0.0f;

        m_mass = massData.mass;
        if (m_mass <= 0.0f) {
            m_mass = 1f;
        }

        m_invMass = 1.0f / m_mass;

        if (massData.I > 0.0f && (m_flags & E_FIXED_ROTATION_FLAG) == 0) {
            m_I = massData.I - m_mass * Vec2.dot(massData.center, massData.center);
            assert (m_I > 0.0f);
            m_invI = 1.0f / m_I;
        }

        final Vec2 oldCenter = m_world.getPool().popVec2();
        // Move center of mass.
        oldCenter.set(m_sweep.c);
        m_sweep.localCenter.set(massData.center);
        // m_sweep.c0 = m_sweep.c = Mul(m_xf, m_sweep.localCenter);
        Transform.mulToOutUnsafe(m_xf, m_sweep.localCenter, m_sweep.c0);
        m_sweep.c.set(m_sweep.c0);

        // Update center of mass velocity.
        // m_linearVelocity += Cross(m_angularVelocity, m_sweep.c - oldCenter);
        final Vec2 temp = m_world.getPool().popVec2();
        temp.set(m_sweep.c).subLocal(oldCenter);
        Vec2.crossToOut(m_angularVelocity, temp, temp);
        m_linearVelocity.addLocal(temp);

        m_world.getPool().pushVec2(2);
    }

    private final MassData pmd = new MassData();

    /**
     * This resets the mass properties to the sum of the mass properties of the
     * fixtures. This normally does not need to be called unless you called
     * setMassData to override the mass and you later want to reset the mass.
     */
    public final void resetMassData() {
        // Compute mass data from shapes. Each shape has its own density.
        m_mass = 0.0f;
        m_invMass = 0.0f;
        m_I = 0.0f;
        m_invI = 0.0f;
        m_sweep.localCenter.setZero();

        // Static and kinematic bodies have zero mass.
        if (m_type == BodyType.STATIC || m_type == BodyType.KINEMATIC) {
            // m_sweep.c0 = m_sweep.c = m_xf.position;
            m_sweep.c0.set(m_xf.p);
            m_sweep.c.set(m_xf.p);
            m_sweep.a0 = m_sweep.a;
            return;
        }

        assert (m_type == BodyType.DYNAMIC);

        // Accumulate mass over all fixtures.
        final Vec2 localCenter = m_world.getPool().popVec2();
        localCenter.setZero();
        final Vec2 temp = m_world.getPool().popVec2();
        final MassData massData = pmd;
        for (Fixture f = m_fixtureList; f != null; f = f.m_next) {
            if (f.m_density == 0.0f) {
                continue;
            }
            f.getMassData(massData);
            m_mass += massData.mass;
            // center += massData.mass * massData.center;
            temp.set(massData.center).mulLocal(massData.mass);
            localCenter.addLocal(temp);
            m_I += massData.I;
        }

        // Compute center of mass.
        if (m_mass > 0.0f) {
            m_invMass = 1.0f / m_mass;
            localCenter.mulLocal(m_invMass);
        } else {
            // Force all dynamic bodies to have a positive mass.
            m_mass = 1.0f;
            m_invMass = 1.0f;
        }

        if (m_I > 0.0f && (m_flags & E_FIXED_ROTATION_FLAG) == 0) {
            // Center the inertia about the center of mass.
            m_I -= m_mass * Vec2.dot(localCenter, localCenter);
            assert (m_I > 0.0f);
            m_invI = 1.0f / m_I;
        } else {
            m_I = 0.0f;
            m_invI = 0.0f;
        }

        Vec2 oldCenter = m_world.getPool().popVec2();
        // Move center of mass.
        oldCenter.set(m_sweep.c);
        m_sweep.localCenter.set(localCenter);
        // m_sweep.c0 = m_sweep.c = Mul(m_xf, m_sweep.localCenter);
        Transform.mulToOutUnsafe(m_xf, m_sweep.localCenter, m_sweep.c0);
        m_sweep.c.set(m_sweep.c0);

        // Update center of mass velocity.
        // m_linearVelocity += Cross(m_angularVelocity, m_sweep.c - oldCenter);
        temp.set(m_sweep.c).subLocal(oldCenter);

        final Vec2 temp2 = oldCenter;
        Vec2.crossToOutUnsafe(m_angularVelocity, temp, temp2);
        m_linearVelocity.addLocal(temp2);

        m_world.getPool().pushVec2(3);
    }

    /**
     * Get the world coordinates of a point given the local coordinates.
     *
     * @param localPoint a point on the body measured relative the the body's
     * origin.
     * @return the same point expressed in world coordinates.
     */
    public final Vec2 getWorldPoint(Vec2 localPoint) {
        Vec2 v = new Vec2();
        getWorldPointToOut(localPoint, v);
        return v;
    }

    public final void getWorldPointToOut(Vec2 localPoint, Vec2 out) {
        Transform.mulToOut(m_xf, localPoint, out);
    }

    /**
     * Get the world coordinates of a vector given the local coordinates.
     *
     * @param localVector a vector fixed in the body.
     * @return the same vector expressed in world coordinates.
     */
    public final Vec2 getWorldVector(Vec2 localVector) {
        Vec2 out = new Vec2();
        getWorldVectorToOut(localVector, out);
        return out;
    }

    public final void getWorldVectorToOut(Vec2 localVector, Vec2 out) {
        Rot.mulToOut(m_xf.q, localVector, out);
    }

    public final void getWorldVectorToOutUnsafe(Vec2 localVector, Vec2 out) {
        Rot.mulToOutUnsafe(m_xf.q, localVector, out);
    }

    /**
     * Gets a local point relative to the body's origin given a world point.
     *
     * @param worldPoint a point in world coordinates.
     * @return the corresponding local point relative to the body's origin.
     */
    public final Vec2 getLocalPoint(Vec2 worldPoint) {
        Vec2 out = new Vec2();
        getLocalPointToOut(worldPoint, out);
        return out;
    }

    public final void getLocalPointToOut(Vec2 worldPoint, Vec2 out) {
        Transform.mulTransToOut(m_xf, worldPoint, out);
    }

    /**
     * Gets a local vector given a world vector.
     *
     * @param worldVector a vector in world coordinates.
     * @return the corresponding local vector.
     */
    public final Vec2 getLocalVector(Vec2 worldVector) {
        Vec2 out = new Vec2();
        getLocalVectorToOut(worldVector, out);
        return out;
    }

    public final void getLocalVectorToOut(Vec2 worldVector, Vec2 out) {
        Rot.mulTrans(m_xf.q, worldVector, out);
    }

    public final void getLocalVectorToOutUnsafe(Vec2 worldVector, Vec2 out) {
        Rot.mulTransUnsafe(m_xf.q, worldVector, out);
    }

    /**
     * Get the world linear velocity of a world point attached to this body.
     *
     * @param worldPoint a point in world coordinates.
     * @return the world velocity of a point.
     */
    public final Vec2 getLinearVelocityFromWorldPoint(Vec2 worldPoint) {
        Vec2 out = new Vec2();
        getLinearVelocityFromWorldPointToOut(worldPoint, out);
        return out;
    }

    public final void getLinearVelocityFromWorldPointToOut(Vec2 worldPoint, Vec2 out) {
        final float tempX = worldPoint.x - m_sweep.c.x;
        final float tempY = worldPoint.y - m_sweep.c.y;
        out.x = -m_angularVelocity * tempY + m_linearVelocity.x;
        out.y = m_angularVelocity * tempX + m_linearVelocity.y;
    }

    /**
     * Get the world velocity of a local point.
     *
     * @param localPoint a point in local coordinates.
     * @return the world velocity of a point.
     */
    public final Vec2 getLinearVelocityFromLocalPoint(Vec2 localPoint) {
        Vec2 out = new Vec2();
        getLinearVelocityFromLocalPointToOut(localPoint, out);
        return out;
    }

    public final void getLinearVelocityFromLocalPointToOut(Vec2 localPoint, Vec2 out) {
        getWorldPointToOut(localPoint, out);
        getLinearVelocityFromWorldPointToOut(out, out);
    }

    /**
     * Get the linear damping of the body.
     *
     * @return
     */
    public final float getLinearDamping() {
        return m_linearDamping;
    }

    /**
     * Set the linear damping of the body.
     *
     * @param linearDamping
     */
    public final void setLinearDamping(float linearDamping) {
        m_linearDamping = linearDamping;
    }

    /**
     * Get the angular damping of the body.
     *
     * @return
     */
    public final float getAngularDamping() {
        return m_angularDamping;
    }

    /**
     * Set the angular damping of the body.
     *
     * @param angularDamping
     */
    public final void setAngularDamping(float angularDamping) {
        m_angularDamping = angularDamping;
    }

    public BodyType getType() {
        return m_type;
    }

    /**
     * Set the type of this body. This may alter the mass and velocity.
     *
     * @param type
     */
    public void setType(BodyType type) {
        assert (m_world.isLocked() == false);
        if (m_world.isLocked() == true) {
            return;
        }

        if (m_type == type) {
            return;
        }

        m_type = type;

        resetMassData();

        if (m_type == BodyType.STATIC) {
            m_linearVelocity.setZero();
            m_angularVelocity = 0.0f;
            m_sweep.a0 = m_sweep.a;
            m_sweep.c0.set(m_sweep.c);
            synchronizeFixtures();
        }

        setAwake(true);

        m_force.setZero();
        m_torque = 0.0f;

        // Delete the attached contacts.
        ContactEdge ce = m_contactList;
        while (ce != null) {
            ContactEdge ce0 = ce;
            ce = ce.next;
            m_world.m_contactManager.destroy(ce0.contact);
        }
        m_contactList = null;

        // Touch the proxies so that new contacts will be created (when appropriate)
        BroadPhase broadPhase = m_world.m_contactManager.m_broadPhase;
        for (Fixture f = m_fixtureList; f != null; f = f.m_next) {
            int proxyCount = f.m_proxyCount;
            for (int i = 0; i < proxyCount; ++i) {
                broadPhase.touchProxy(f.m_proxies[i].proxyId);
            }
        }
    }

    /**
     * Is this body treated like a bullet for continuous collision detection?
     *
     * @return
     */
    public final boolean isBullet() {
        return (m_flags & E_BULLET_FLAG) == E_BULLET_FLAG;
    }

    /**
     * Should this body be treated like a bullet for continuous collision
     * detection?
     *
     * @param flag
     */
    public final void setBullet(boolean flag) {
        if (flag) {
            m_flags |= E_BULLET_FLAG;
        } else {
            m_flags &= ~E_BULLET_FLAG;
        }
    }

    /**
     * You can disable sleeping on this body. If you disable sleeping, the body
     * will be woken.
     *
     * @param flag
     */
    public void setSleepingAllowed(boolean flag) {
        if (flag) {
            m_flags |= E_AUTO_SLEEP_FLAG;
        } else {
            m_flags &= ~E_AUTO_SLEEP_FLAG;
            setAwake(true);
        }
    }

    /**
     * Is this body allowed to sleep
     *
     * @return
     */
    public boolean isSleepingAllowed() {
        return (m_flags & E_AUTO_SLEEP_FLAG) == E_AUTO_SLEEP_FLAG;
    }

    /**
     * Set the sleep state of the body. A sleeping body has very low CPU cost.
     *
     * @param flag set to true to put body to sleep, false to wake it.
     */
    public void setAwake(boolean flag) {
        if (flag) {
            if ((m_flags & E_AWAKE_FLAG) == 0) {
                m_flags |= E_AWAKE_FLAG;
                m_sleepTime = 0.0f;
            }
        } else {
            m_flags &= ~E_AWAKE_FLAG;
            m_sleepTime = 0.0f;
            m_linearVelocity.setZero();
            m_angularVelocity = 0.0f;
            m_force.setZero();
            m_torque = 0.0f;
        }
    }

    /**
     * Get the sleeping state of this body.
     *
     * @return true if the body is awake.
     */
    public boolean isAwake() {
        return (m_flags & E_AWAKE_FLAG) == E_AWAKE_FLAG;
    }

    /**
     * Set the active state of the body. An inactive body is not simulated and
     * cannot be collided with or woken up. If you pass a flag of true, all
     * fixtures will be added to the broad-phase. If you pass a flag of false,
     * all fixtures will be removed from the broad-phase and all contacts will
     * be destroyed. Fixtures and joints are otherwise unaffected. You may
     * continue to create/destroy fixtures and joints on inactive bodies.
     * Fixtures on an inactive body are implicitly inactive and will not
     * participate in collisions, ray-casts, or queries. Joints connected to an
     * inactive body are implicitly inactive. An inactive body is still owned by
     * a World object and remains in the body list.
     *
     * @param flag
     */
    public void setActive(boolean flag) {
        assert (m_world.isLocked() == false);

        if (flag == isActive()) {
            return;
        }

        if (flag) {
            m_flags |= E_ACTIVE_FLAG;

            // Create all proxies.
            BroadPhase broadPhase = m_world.m_contactManager.m_broadPhase;
            for (Fixture f = m_fixtureList; f != null; f = f.m_next) {
                f.createProxies(broadPhase, m_xf);
            }

            // Contacts are created the next time step.
        } else {
            m_flags &= ~E_ACTIVE_FLAG;

            // Destroy all proxies.
            BroadPhase broadPhase = m_world.m_contactManager.m_broadPhase;
            for (Fixture f = m_fixtureList; f != null; f = f.m_next) {
                f.destroyProxies(broadPhase);
            }

            // Destroy the attached contacts.
            ContactEdge ce = m_contactList;
            while (ce != null) {
                ContactEdge ce0 = ce;
                ce = ce.next;
                m_world.m_contactManager.destroy(ce0.contact);
            }
            m_contactList = null;
        }
    }

    /**
     * Get the active state of the body.
     *
     * @return
     */
    public boolean isActive() {
        return (m_flags & E_ACTIVE_FLAG) == E_ACTIVE_FLAG;
    }

    /**
     * Set this body to have fixed rotation. This causes the mass to be reset.
     *
     * @param flag
     */
    public void setFixedRotation(boolean flag) {
        if (flag) {
            m_flags |= E_FIXED_ROTATION_FLAG;
        } else {
            m_flags &= ~E_FIXED_ROTATION_FLAG;
        }

        resetMassData();
    }

    /**
     * Does this body have fixed rotation?
     *
     * @return
     */
    public boolean isFixedRotation() {
        return (m_flags & E_FIXED_ROTATION_FLAG) == E_FIXED_ROTATION_FLAG;
    }

    /**
     * Get the list of all fixtures attached to this body.
     *
     * @return
     */
    public final Fixture getFixtureList() {
        return m_fixtureList;
    }

    /**
     * Get the list of all joints attached to this body.
     *
     * @return
     */
    public final JointEdge getJointList() {
        return m_jointList;
    }

    /**
     * Get the list of all contacts attached to this body.
     *
     * @return
     * @warning this list changes during the time step and you may miss some
     * collisions if you don't use ContactListener.
     */
    public final ContactEdge getContactList() {
        return m_contactList;
    }

    /**
     * Get the next body in the world's body list.
     *
     * @return
     */
    public final Body getNext() {
        return m_next;
    }

    /**
     * Get the user data pointer that was provided in the body definition.
     *
     * @return
     */
    public final Object getUserData() {
        return m_userData;
    }

    /**
     * Set the user data. Use this to store your application specific data.
     *
     * @param data
     */
    public final void setUserData(Object data) {
        m_userData = data;
    }

    /**
     * Get the parent world of this body.
     *
     * @return
     */
    public final World getWorld() {
        return m_world;
    }

    // djm pooling
    private final Transform pxf = new Transform();

    protected final void synchronizeFixtures() {
        final Transform xf1 = pxf;
        // xf1.position = m_sweep.c0 - Mul(xf1.R, m_sweep.localCenter);

        // xf1.q.set(m_sweep.a0);
        // Rot.mulToOutUnsafe(xf1.q, m_sweep.localCenter, xf1.p);
        // xf1.p.mulLocal(-1).addLocal(m_sweep.c0);
        // inlined:
        xf1.q.s = MathUtils.sin(m_sweep.a0);
        xf1.q.c = MathUtils.cos(m_sweep.a0);
        xf1.p.x = m_sweep.c0.x - xf1.q.c * m_sweep.localCenter.x + xf1.q.s * m_sweep.localCenter.y;
        xf1.p.y = m_sweep.c0.y - xf1.q.s * m_sweep.localCenter.x - xf1.q.c * m_sweep.localCenter.y;
        // end inline

        for (Fixture f = m_fixtureList; f != null; f = f.m_next) {
            f.synchronize(m_world.m_contactManager.m_broadPhase, xf1, m_xf);
        }
    }

    public final void synchronizeTransform() {
        // m_xf.q.set(m_sweep.a);
        //
        // // m_xf.position = m_sweep.c - Mul(m_xf.R, m_sweep.localCenter);
        // Rot.mulToOutUnsafe(m_xf.q, m_sweep.localCenter, m_xf.p);
        // m_xf.p.mulLocal(-1).addLocal(m_sweep.c);
        //
        m_xf.q.s = MathUtils.sin(m_sweep.a);
        m_xf.q.c = MathUtils.cos(m_sweep.a);
        Rot q = m_xf.q;
        Vec2 v = m_sweep.localCenter;
        m_xf.p.x = m_sweep.c.x - q.c * v.x + q.s * v.y;
        m_xf.p.y = m_sweep.c.y - q.s * v.x - q.c * v.y;
    }

    /**
     * This is used to prevent connected bodies from colliding. It may lie,
     * depending on the collideConnected flag.
     *
     * @param other
     * @return
     */
    public boolean shouldCollide(Body other) {
        // At least one body should be dynamic.
        if (m_type != BodyType.DYNAMIC && other.m_type != BodyType.DYNAMIC) {
            return false;
        }

        // Does a joint prevent collision?
        for (JointEdge jn = m_jointList; jn != null; jn = jn.next) {
            if (jn.other == other) {
                if (jn.joint.getCollideConnected() == false) {
                    return false;
                }
            }
        }

        return true;
    }

    protected final void advance(float t) {
        // Advance to the new safe time. This doesn't sync the broad-phase.
        m_sweep.advance(t);
        m_sweep.c.set(m_sweep.c0);
        m_sweep.a = m_sweep.a0;
        m_xf.q.set(m_sweep.a);
        // m_xf.position = m_sweep.c - Mul(m_xf.R, m_sweep.localCenter);
        Rot.mulToOutUnsafe(m_xf.q, m_sweep.localCenter, m_xf.p);
        m_xf.p.mulLocal(-1).addLocal(m_sweep.c);
    }
}