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love-canvas_getPixel / src / modules / physics / box2d / Joint.h

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/**
 * Copyright (c) 2006-2012 LOVE Development Team
 *
 * 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 LOVE_PHYSICS_BOX2D_JOINT_H
#define LOVE_PHYSICS_BOX2D_JOINT_H

// LOVE
#include "common/runtime.h"
#include "physics/Joint.h"

// Box2D
#include <Box2D/Box2D.h>

namespace love
{
namespace physics
{
namespace box2d
{

// Forward declarations.
class Body;
class World;

/**
 * A Joint acts as positioning constraints on Bodies.
 * A Joint can be used to prevent Bodies from going to
 * far apart, or coming too close together.
 **/
class Joint : public love::physics::Joint
{
public:
	friend class GearJoint;

	/**
	 * This constructor will connect one end of the joint to body1,
	 * and the other one to the default ground body.
	 *
	 * This constructor is mainly used by MouseJoint.
	 **/
	Joint(Body *body1);

	/**
	 * Create a joint between body1 and body2.
	 **/
	Joint(Body *body1, Body *body2);

	virtual ~Joint();

	/**
	 * Returns true if the joint is active in a Box2D world.
	 **/
	bool isValid() const;


	/**
	 * Gets the type of joint.
	 **/
	Type getType() const;

	/**
	 * Gets the anchor positions of the Joint in world
	 * coordinates. This is useful for debugdrawing the joint.
	 **/
	int getAnchors(lua_State *L);

	/**
	 * Gets the reaction force on body2 at the joint anchor.
	 **/
	int getReactionForce(lua_State *L);

	/**
	 * Gets the reaction torque on body2.
	 **/
	float getReactionTorque(float dt);

	bool isActive() const;

	bool getCollideConnected() const;

	/**
	 * Joints require pointers to a Box2D joint objects at
	 * different polymorphic levels, which is why these function
	 * were created.
	 **/

	/**
	 * Destroys the joint. This function was created just to
	 * get some cinsistency.
	 **/
	void destroyJoint(bool implicit = false);

protected:

	/**
	 * Creates a Joint, and ensures that the parent class
	 * gets a copy of the pointer.
	 **/
	b2Joint *createJoint(b2JointDef *def);

	World *world;

private:

	// A Joint must be destroyed *before* the bodies it acts upon,
	// and the world they reside in. We therefore need refs
	// parents and associations to prevent wrong destruction order.
	Body *body1, * body2;


	// The Box2D joint object.
	b2Joint *joint;

};

} // box2d
} // physics
} // love

#endif // LOVE_PHYSICS_BOX2D_JOINT_H