/*
* Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com
*
* 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 B2_SETTINGS_H
#define B2_SETTINGS_H

#include <cassert>
#include <cmath>

#define B2_NOT_USED(x) ((void)(x))
#define b2Assert(A) assert(A)

typedef signed char	int8;
typedef signed short int16;
typedef signed int int32;
typedef unsigned char uint8;
typedef unsigned short uint16;
typedef unsigned int uint32;
typedef float float32;

#define	b2_maxFloat		FLT_MAX
#define	b2_epsilon		FLT_EPSILON
#define b2_pi			3.14159265359f

/// @file
/// Global tuning constants based on meters-kilograms-seconds (MKS) units.
///

// Collision

/// The maximum number of contact points between two convex shapes.
#define b2_maxManifoldPoints	2

/// The maximum number of vertices on a convex polygon.
#define b2_maxPolygonVertices	8

/// This is used to fatten AABBs in the dynamic tree. This allows proxies
/// to move by a small amount without triggering a tree adjustment.
/// This is in meters.
#define b2_aabbExtension		0.1f

/// This is used to fatten AABBs in the dynamic tree. This is used to predict
/// the future position based on the current displacement.
/// This is a dimensionless multiplier.
#define b2_aabbMultiplier		2.0f

/// A small length used as a collision and constraint tolerance. Usually it is
/// chosen to be numerically significant, but visually insignificant.
#define b2_linearSlop			0.005f

/// A small angle used as a collision and constraint tolerance. Usually it is
/// chosen to be numerically significant, but visually insignificant.
#define b2_angularSlop			(2.0f / 180.0f * b2_pi)

/// The radius of the polygon/edge shape skin. This should not be modified. Making
/// this smaller means polygons will have an insufficient buffer for continuous collision.
/// Making it larger may create artifacts for vertex collision.
#define b2_polygonRadius		(2.0f * b2_linearSlop)


// Dynamics

/// Maximum number of contacts to be handled to solve a TOI impact.
#define b2_maxTOIContacts			32

/// A velocity threshold for elastic collisions. Any collision with a relative linear
/// velocity below this threshold will be treated as inelastic.
#define b2_velocityThreshold		1.0f

/// The maximum linear position correction used when solving constraints. This helps to
/// prevent overshoot.
#define b2_maxLinearCorrection		0.2f

/// The maximum angular position correction used when solving constraints. This helps to
/// prevent overshoot.
#define b2_maxAngularCorrection		(8.0f / 180.0f * b2_pi)

/// The maximum linear velocity of a body. This limit is very large and is used
/// to prevent numerical problems. You shouldn't need to adjust this.
#define b2_maxTranslation			2.0f
#define b2_maxTranslationSquared	(b2_maxTranslation * b2_maxTranslation)

/// The maximum angular velocity of a body. This limit is very large and is used
/// to prevent numerical problems. You shouldn't need to adjust this.
#define b2_maxRotation				(0.5f * b2_pi)
#define b2_maxRotationSquared		(b2_maxRotation * b2_maxRotation)

/// This scale factor controls how fast overlap is resolved. Ideally this would be 1 so
/// that overlap is removed in one time step. However using values close to 1 often lead
/// to overshoot.
#define b2_contactBaumgarte			0.2f

// Sleep

/// The time that a body must be still before it will go to sleep.
#define b2_timeToSleep				0.5f

/// A body cannot sleep if its linear velocity is above this tolerance.
#define b2_linearSleepTolerance		0.01f

/// A body cannot sleep if its angular velocity is above this tolerance.
#define b2_angularSleepTolerance	(2.0f / 180.0f * b2_pi)

// Memory Allocation

/// Implement this function to use your own memory allocator.
void* b2Alloc(int32 size);

/// If you implement b2Alloc, you should also implement this function.
void b2Free(void* mem);

/// Version numbering scheme.
/// See http://en.wikipedia.org/wiki/Software_versioning
struct b2Version
{
	int32 major;		///< significant changes
	int32 minor;		///< incremental changes
	int32 revision;		///< bug fixes
};

/// Current version.
extern b2Version b2_version;

/// Friction mixing law. Feel free to customize this.
inline float32 b2MixFriction(float32 friction1, float32 friction2)
{
	return sqrtf(friction1 * friction2);
}

/// Restitution mixing law. Feel free to customize this.
inline float32 b2MixRestitution(float32 restitution1, float32 restitution2)
{
	return restitution1 > restitution2 ? restitution1 : restitution2;
}

#endif

