BansheeEngine/BansheeCore/Include/BsJoint.h

//********************************** Banshee Engine (www.banshee3d.com) **************************************************//
//**************** Copyright (c) 2016 Marko Pintera ([email protected]). All rights reserved. **********************//
#pragma once

#include "BsCorePrerequisites.h"
#include "BsFJoint.h"

namespace BansheeEngine
{
	/** @addtogroup Physics
	 *  @{
	 */

	/** 
	 * Base class for all Joint types. Joints constrain how two rigidbodies move relative to one another (e.g. a door 
	 * hinge). One of the bodies in the joint must always be movable (i.e. non-kinematic).
	 */
	class BS_CORE_EXPORT Joint
	{
	public:
		virtual ~Joint() { }

		/** @copydoc FJoint::getBody */
		inline Rigidbody* getBody(JointBody body) const;

		/** @copydoc FJoint::setBody */
		inline void setBody(JointBody body, Rigidbody* value);

		/** @copydoc FJoint::getPosition */
		inline Vector3 getPosition(JointBody body) const;

		/** @copydoc FJoint::getRotation */
		inline Quaternion getRotation(JointBody body) const;

		/** @copydoc FJoint::setTransform */
		inline void setTransform(JointBody body, const Vector3& position, const Quaternion& rotation);

		/** @copydoc FJoint::getBreakForce */
		inline float getBreakForce() const;

		/** @copydoc FJoint::setBreakForce */
		inline void setBreakForce(float force);

		/** @copydoc FJoint::getBreakTorque */
		inline float getBreakTorque() const;

		/** @copydoc FJoint::setBreakTorque */
		inline void setBreakTorque(float torque);

		/** @copydoc FJoint::getEnableCollision */
		inline bool getEnableCollision() const;

		/** @copydoc FJoint::setEnableCollision */
		inline void setEnableCollision(bool value);

		/** Triggered when the joint's break force or torque is exceeded. */
		Event<void()> onJointBreak;
	protected:
		FJoint* mInternal = nullptr;
	};

	/** 
	 * Controls spring parameters for a physics joint limits. If a limit is soft (body bounces back due to restition when 
	 * the limit is reached) the spring will pull the body back towards the limit using the specified parameters.
	 */
	struct Spring
	{
		/** Constructs a spring with no force. */
		Spring() { }

		/** 
		 * Constructs a spring. 
		 *
		 * @param	stiffness	Spring strength. Force proportional to the position error.
		 * @param	damping		Damping strength. Force propertional to the velocity error.
		 */
		Spring(float stiffness, float damping)
			:stiffness(stiffness), damping(damping)
		{ }

		bool operator==(const Spring& other) const
		{
			return stiffness == other.stiffness && damping == other.damping;
		}

		/** Spring strength. Force proportional to the position error. */
		float stiffness = 0.0f;

		/** Damping strength. Force propertional to the velocity error. */
		float damping = 0.0f;
	};

	/** Contains common values used by all Joint limit types. */
	struct LimitCommon
	{
		LimitCommon(float contactDist = -1.0f)
			:contactDist(contactDist)
		{ }

		LimitCommon(const Spring& spring, float restitution = 0.0f)
			:spring(spring), restitution(restitution)
		{ }

		/** 
		 * Distance from the limit at which it becomes active. Allows the solver to activate earlier than the limit is
		 * reached to avoid breaking the limit.
		 */
		float contactDist = -1.0f;

		/**
		 * Controls how do objects react when the limit is reached, values closer to zero specify non-ellastic collision,
		 * while those closer to one specify more ellastic (i.e bouncy) collision. Must be in [0, 1] range.
		 */
		float restitution = 0.0f;

		/** Spring that controls how are the bodies pulled back towards the limit when they breach it. */
		Spring spring;
	};

	/** Represents a joint limit between two distance values. Lower value must be less than the upper value. */
	struct LimitLinearRange : LimitCommon
	{
		/** Constructs an empty limit. */
		LimitLinearRange()
		{ }

		/**
		 * Constructs a hard limit. Once the limit is reached the movement of the attached bodies will come to a stop.
		 * 
		 * @param	lower		Lower distance of the limit. Must be less than @p upper.
		 * @param	upper		Upper distance of the limit. Must be more than @p lower.
		 * @param	contactDist	Distance from the limit at which it becomes active. Allows the solver to activate earlier
		 *						than the limit is reached to avoid breaking the limit. Specify -1 for the default.
		 */
		LimitLinearRange(float lower, float upper, float contactDist = -1.0f)
			:LimitCommon(contactDist), lower(lower), upper(upper)
		{ }

		/**
		 * Constructs a soft limit. Once the limit is reached the bodies will bounce back according to the resitution
		 * parameter and will be pulled back towards the limit by the provided spring.
		 * 
		 * @param	lower		Lower distance of the limit. Must be less than @p upper.
		 * @param	upper		Upper distance of the limit. Must be more than @p lower.
		 * @param	spring		Spring that controls how are the bodies pulled back towards the limit when they breach it.
		 * @param	resitution	Controls how do objects react when the limit is reached, values closer to zero specify
		 *						non-ellastic collision, while those closer to one specify more ellastic (i.e bouncy)
		 *						collision. Must be in [0, 1] range.
		 */
		LimitLinearRange(float lower, float upper, const Spring& spring, float restitution = 0.0f)
			:LimitCommon(spring, restitution), lower(lower), upper(upper)
		{ }

		bool operator==(const LimitLinearRange& other) const
		{
			return lower == other.lower && upper == other.upper && contactDist == other.contactDist && 
				restitution == other.restitution && spring == other.spring;
		}

		/** Lower distance of the limit. Must be less than #upper. */
		float lower = 0.0f; 

		/** Upper distance of the limit. Must be more than #lower. */
		float upper = 0.0f;
	};

	/** Represents a joint limit between zero a single distance value. */
	struct LimitLinear : LimitCommon
	{
		/** Constructs an empty limit. */
		LimitLinear()
		{ }

		/**
		 * Constructs a hard limit. Once the limit is reached the movement of the attached bodies will come to a stop.
		 * 
		 * @param	extent		Distance at which the limit becomes active. 
		 * @param	contactDist	Distance from the limit at which it becomes active. Allows the solver to activate earlier
		 *						than the limit is reached to avoid breaking the limit. Specify -1 for the default.
		 */
		LimitLinear(float extent, float contactDist = -1.0f)
			:LimitCommon(contactDist), extent(extent)
		{ }

		/**
		 * Constructs a soft limit. Once the limit is reached the bodies will bounce back according to the resitution
		 * parameter and will be pulled back towards the limit by the provided spring.
		 * 
		 * @param	extent		Distance at which the limit becomes active. 
		 * @param	spring		Spring that controls how are the bodies pulled back towards the limit when they breach it.
		 * @param	resitution	Controls how do objects react when the limit is reached, values closer to zero specify
		 *						non-ellastic collision, while those closer to one specify more ellastic (i.e bouncy)
		 *						collision. Must be in [0, 1] range.
		 */
		LimitLinear(float extent, const Spring& spring, float restitution = 0.0f)
			:LimitCommon(spring, restitution), extent(extent)
		{ }

		bool operator==(const LimitLinear& other) const
		{
			return extent == other.extent && contactDist == other.contactDist && restitution == other.restitution &&
				spring == other.spring;
		}

		/** Distance at which the limit becomes active. */
		float extent = 0.0f;
	};

	/** Represents a joint limit between two angles. */
	struct LimitAngularRange : LimitCommon
	{
		/** Constructs an empty limit. */
		LimitAngularRange()
		{ }

		/**
		 * Constructs a hard limit. Once the limit is reached the movement of the attached bodies will come to a stop.
		 * 
		 * @param	lower		Lower angle of the limit. Must be less than @p upper.
		 * @param	upper		Upper angle of the limit. Must be more than @p lower.
		 * @param	contactDist	Distance from the limit at which it becomes active. Allows the solver to activate earlier
		 *						than the limit is reached to avoid breaking the limit. Specify -1 for the default.
		 */
		LimitAngularRange(Radian lower, Radian upper, float contactDist = -1.0f)
			:LimitCommon(contactDist), lower(lower), upper(upper)
		{ }

		/**
		 * Constructs a soft limit. Once the limit is reached the bodies will bounce back according to the resitution
		 * parameter and will be pulled back towards the limit by the provided spring.
		 * 
		 * @param	lower		Lower angle of the limit. Must be less than @p upper.
		 * @param	upper		Upper angle of the limit. Must be more than @p lower.
		 * @param	spring		Spring that controls how are the bodies pulled back towards the limit when they breach it.
		 * @param	resitution	Controls how do objects react when the limit is reached, values closer to zero specify
		 *						non-ellastic collision, while those closer to one specify more ellastic (i.e bouncy)
		 *						collision. Must be in [0, 1] range.
		 */
		LimitAngularRange(Radian lower, Radian upper, const Spring& spring, float restitution = 0.0f)
			:LimitCommon(spring, restitution), lower(lower), upper(upper)
		{ }

		bool operator==(const LimitAngularRange& other) const
		{
			return lower == other.lower && upper == other.upper && contactDist == other.contactDist && 
				restitution == other.restitution && spring == other.spring;
		}

		/** Lower angle of the limit. Must be less than #upper. */
		Radian lower = Radian(0.0f);

		/** Upper angle of the limit. Must be less than #lower. */
		Radian upper = Radian(0.0f);
	};

	/** Represents a joint limit that contraints movement to within an elliptical cone. */
	struct LimitConeRange : LimitCommon
	{
		/** Constructs a limit with a 45 degree cone. */
		LimitConeRange()
		{ }

		/**
		 * Constructs a hard limit. Once the limit is reached the movement of the attached bodies will come to a stop.
		 * 
		 * @param	yLimitAngle		Y angle of the cone. Movement is constrainted between 0 and this angle on the Y axis.
		 * @param	zLimitAngle		Z angle of the cone. Movement is constrainted between 0 and this angle on the Z axis.
		 * @param	contactDist		Distance from the limit at which it becomes active. Allows the solver to activate 
		 *							earlier than the limit is reached to avoid breaking the limit. Specify -1 for the 
		 *							default.
		 */
		LimitConeRange(Radian yLimitAngle, Radian zLimitAngle, float contactDist = -1.0f)
			:LimitCommon(contactDist), yLimitAngle(yLimitAngle), zLimitAngle(zLimitAngle)
		{ }

		/**
		 * Constructs a soft limit. Once the limit is reached the bodies will bounce back according to the resitution
		 * parameter and will be pulled back towards the limit by the provided spring.
		 * 
		 * @param	yLimitAngle	Y angle of the cone. Movement is constrainted between 0 and this angle on the Y axis.
		 * @param	zLimitAngle	Z angle of the cone. Movement is constrainted between 0 and this angle on the Z axis.
		 * @param	spring		Spring that controls how are the bodies pulled back towards the limit when they breach it.
		 * @param	resitution	Controls how do objects react when the limit is reached, values closer to zero specify
		 *						non-ellastic collision, while those closer to one specify more ellastic (i.e bouncy)
		 *						collision. Must be in [0, 1] range.
		 */
		LimitConeRange(Radian yLimitAngle, Radian zLimitAngle, const Spring& spring, float restitution = 0.0f)
			:LimitCommon(spring, restitution), yLimitAngle(yLimitAngle), zLimitAngle(zLimitAngle)
		{ }

		bool operator==(const LimitConeRange& other) const
		{
			return yLimitAngle == other.yLimitAngle && zLimitAngle == other.zLimitAngle && 
				contactDist == other.contactDist && restitution == other.restitution && spring == other.spring;
		}

		/** Y angle of the cone. Movement is constrainted between 0 and this angle on the Y axis. */
		Radian yLimitAngle = Radian(Math::PI * 0.5f);

		/** Z angle of the cone. Movement is constrainted between 0 and this angle on the Z axis. */
		Radian zLimitAngle = Radian(Math::PI * 0.5f);
	};

	/** @} */
}