love/src/modules/physics/box2d/Contact.h

/**
 * Copyright (c) 2006-2020 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_CONTACT_H
#define LOVE_PHYSICS_BOX2D_CONTACT_H

// LOVE
#include "common/Object.h"
#include "common/runtime.h"
#include "World.h"

// Box2D
#include <box2d/Box2D.h>

namespace love
{
namespace physics
{
namespace box2d
{

class World;

/**
 * A Contact represents a collision point between
 * two shapes.
 **/
class Contact : public Object
{
public:
	// Friends.
	friend class World;
	friend class World::ContactCallback;

	static love::Type type;

	/**
	 * Creates a new Contact by copying a Box2D contact
	 * point. It does not store the pointer, but copy the
	 * data pointed to.
	 * @param contact Pointer to the Box2D contact.
	 **/
	Contact(World *world, b2Contact *contact);

	virtual ~Contact();

	/**
	 * Removes the b2Contact pointer from Memoizer and sets it
	 * to null on the Contact.
	 **/
	void invalidate();

	/**
	 * Returns if the Contact still points to a valid b2Contact.
	 * @return True if the contact is still valid or false if it has been destroyed.
	 **/
	bool isValid();

	/**
	 * Gets the position of each point of contact.
	 * @return The position along the x-axis.
	 * @return The position along the y-axis.
	 **/
	int getPositions(lua_State *L);

	/**
	 * Gets the collision normal.
	 * @return The x-component of the normal.
	 * @return The y-component of the normal.
	 **/
	int getNormal(lua_State *L);

	/**
	 * The mixed friction between the two fixtures at
	 * the point of impact.
	 **/
	float getFriction() const;

	/**
	 * The mixed restitution of the two fixtures
	 * at the point of impact.
	 **/
	float getRestitution() const;

	/**
	 * Check if the contact is enabled.
	 **/
	bool isEnabled() const;

	/**
	 * Check if the contact is touching.
	 **/
	bool isTouching() const;

	// Only call the setters in PreSolve

	/**
	 * Override the default friction mixture.
	 **/
	void setFriction(float friction);

	/**
	 * Override the default restitution mixture.
	 **/
	void setRestitution(float restitution);

	/**
	 * Enable/disable this contact.
	 **/
	void setEnabled(bool enabled);

	/**
	 * Reset the friction mixture to the default
	 * value.
	 **/
	void resetFriction();

	/**
	 * Reset the restitution mixture to the default
	 * value.
	 **/
	void resetRestitution();

	/**
	 * Set the desired tangent speed.
	 **/
	void setTangentSpeed(float speed);

	/**
	 * Get the desired tangent speed.
	 **/
	float getTangentSpeed() const;

	void getChildren(int &childA, int &childB);

	/**
	 * Gets the Fixtures associated with this Contact.
	 **/
	void getFixtures(Fixture *&fixtureA, Fixture *&fixtureB);

private:

	// The Box2D contact.
	b2Contact *contact;

	World *world;
};

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

#endif // LOVE_PHYSICS_BOX2D_CONTACT_H