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

/**
* Copyright (c) 2006-2009 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_WORLD_H
#define LOVE_PHYSICS_BOX2D_WORLD_H

// LOVE
#include <common/Object.h>
#include <common/runtime.h>
#include <common/Reference.h>

// STD
#include <vector>

// Box2D
#include "Include/Box2D.h"

namespace love
{
namespace physics
{
namespace box2d
{
	
	class Contact;

	/**
	* The World is the "God" container class, 
	* which contains all Bodies and Joints. Shapes
	* are contained in their associated Body. 
	* 
	* Bodies in different worlds can obviously not
	* collide.
	* 
	* The world also controls global parameters, like 
	* gravity.
	**/
	class World : public Object, public b2ContactListener
	{
		// Friends.
		friend class Joint;
		friend class DistanceJoint;
		friend class MouseJoint;
		friend class Body;

	public:

		class ContactCallback
		{
		public:
			Reference * ref;
			std::vector<Contact *> contacts;
			ContactCallback();
			~ContactCallback();
			void add(World * world, const b2ContactPoint* point);
			void process();
		};

	private:

		// Pointer to the Box2D world.
		b2World * world;

		// Contact callbacks.
		ContactCallback add, persist, remove, result;

		// The length of one meter in pixels.
		int meter;

	public:

		/**
		* 30 pixels in one meter by default.
		**/
		static const int DEFAULT_METER = 30;

		/**
		* Creates a new world with the given bounding box.
		* @param aabb The bounding box.
		**/
		World(b2AABB aabb);

		/**
		* Creates a new world with the given bounding box, gravity
		* and whether or not the bodies should sleep when appropriate.
		* @param aabb The bounding box.
		* @param gravity The gravity of the World.
		* @param sleep True if the bodies should be able to sleep,
		* false otherwise.
		**/
		World(b2AABB aabb, b2Vec2 gravity, bool sleep);

		~World();

		/**
		* Updates everything in the world one timestep.
		* This is called update() and not step() to conform
		* with all other objects in LOVE.
		* @param dt The timestep.
		**/
		void update(float dt);

		// From b2ContactListener
		void Add(const b2ContactPoint* point);
		void Persist(const b2ContactPoint* point);
		void Remove(const b2ContactPoint* point);
		void Result(const b2ContactPoint* point);

		/**
		* Receives up to four Lua functions as arguments. Each function is
		* collision callback for the four events (in order): add, persist,
		* remove and result. The value "nil" is accepted if one or more events
		* are uninteresting. 
		**/
		int setCallbacks(lua_State * L);

		/**
		* Returns the functions previously set by setCallbacks.
		**/
		int getCallbacks(lua_State * L);
		
		/**
		* Sets the current gravity of the World.
		* @param x Gravity in the x-direction.
		* @param y Gravity in the y-direction.
		**/
		void setGravity(float x, float y);

		/**
		* Gets the current gravity.
		* @returns Gravity in the x-direction.
		* @returns Gravity in the y-direction.
		**/
		int getGravity(lua_State * L);

		/**
		* Sets whether this World allows sleep.
		* @param allow True to allow, false to disallow.
		**/
		void setAllowSleep(bool allow);

		/**
		* Returns whether this World allows sleep.
		* @return True if allowed, false if disallowed.
		**/
		bool isAllowSleep() const;

		/**
		* Get the current body count.
		* @return The number of bodies.
		**/
		int getBodyCount();

		/**
		* Get the current joint count.
		* @return The number of joints.
		**/
		int getJointCount();

		/**
		* Sets the number of pixels in one meter. 
		* @param pixels The number of pixels in one meter. (1m ~= 3.3ft).
		**/
		void setMeter(int meter);

		/**
		* Gets the number of pixels in one meter.
		* @param pixels The number of pixels in one meter. (1m ~= 3.3ft).
		**/
		int getMeter() const;

		/**
		* Scales a value down according to the current meter in pixels.
		* @param f The unscaled input value.
		**/
		float scaleDown(float f);

		/**
		* Scales a value up according to the current meter in pixels.
		* @param f The unscaled input value.
		**/
		float scaleUp(float f);

		/**
		* Scales a point down according to the current meter
		* in pixels, for instance x = x0/meter, y = x0/meter.
		* @param x The x-coordinate of the point to scale.
		* @param y The y-coordinate of the point to scale.
		**/
		void scaleDown(float & x, float & y);

		/**
		* Scales a point up according to the current meter
		* in pixels, for instance x = x0/meter, y = x0/meter.
		* @param x The x-coordinate of the point to scale.
		* @param y The y-coordinate of the point to scale.
		**/
		void scaleUp(float & x, float & y);

		/**
		* Scales a b2Vec2 down according to the current meter in pixels.
		* @param v The unscaled input vector.
		* @return The scaled vector.
		**/
		b2Vec2 scaleDown(const b2Vec2 & v);

		/**
		* Scales a b2Vec up according to the current meter in pixels.
		* @param v The unscaled input vector.
		* @return The scaled vector.
		**/
		b2Vec2 scaleUp(const b2Vec2 & v);

		/**
		* Scales a b2AABB down according to the current meter in pixels.
		* @param v The unscaled input AABB.
		* @return The scaled AABB.
		**/
		b2AABB scaleDown(const b2AABB & aabb);

		/**
		* Scales a b2AABB up according to the current meter in pixels.
		* @param v The unscaled input AABB.
		* @return The scaled AABB.
		**/
		b2AABB scaleUp(const b2AABB & aabb);

	};

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

#endif // LOVE_PHYSICS_BOX2D_WORLD_H