b2Settings.h

/*
* 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 <assert.h>
#include <math.h>

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

// need to include NDS jtypes.h instead of 
// usual typedefs because NDS jtypes defines
// them slightly differently, oh well.
#ifdef TARGET_IS_NDS

#include "jtypes.h"

#else

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

#endif

#ifdef	TARGET_FLOAT32_IS_FIXED

#include "Fixed.h"

typedef Fixed float32;
#define	B2_FLT_MAX	FIXED_MAX
#define	B2_FLT_EPSILON	FIXED_EPSILON
#define	B2FORCE_SCALE(x)	((x)<<7)
#define	B2FORCE_INV_SCALE(x)	((x)>>7)

#else

typedef float float32;
#define	B2_FLT_MAX	FLT_MAX
#define	B2_FLT_EPSILON	FLT_EPSILON
#define	B2FORCE_SCALE(x)	(x)
#define	B2FORCE_INV_SCALE(x)	(x)

#endif

const float32 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

/// Factor used to fatten AABBs in b2DynamicTree. This allows client
/// objects to move a small amount without needing to adjust the tree.
#define b2_fatAABBFactor			1.5f

/// The initial pool size for the dynamic tree.
#define b2_nodePoolSize				50

/// This must be a power of two
#define b2_maxProxies				512

/// This must be a power of two
#define b2_maxPairs					(8 * b2_maxProxies)

/// The radius of the polygon/edge shape skin.
#define b2_polygonRadius			0.01f

// Dynamics

/// A small length used as a collision and constraint tolerance. Usually it is
/// chosen to be numerically significant, but visually insignificant.
const float32 b2_linearSlop = 0.005f;	// 0.5 cm

/// A small angle used as a collision and constraint tolerance. Usually it is
/// chosen to be numerically significant, but visually insignificant.
const float32 b2_angularSlop = 2.0f / 180.0f * b2_pi;			// 2 degrees

/// Maximum number of contacts to be handled to solve a TOI island.
const int32 b2_maxTOIContactsPerIsland = 32;

/// Maximum number of joints to be handled to solve a TOI island.
const int32 b2_maxTOIJointsPerIsland = 32;

/// A velocity threshold for elastic collisions. Any collision with a relative linear
/// velocity below this threshold will be treated as inelastic.
const float32 b2_velocityThreshold = 1.0f;		// 1 m/s

/// The maximum linear position correction used when solving constraints. This helps to
/// prevent overshoot.
const float32 b2_maxLinearCorrection = 0.2f;	// 20 cm

/// The maximum angular position correction used when solving constraints. This helps to
/// prevent overshoot.
const float32 b2_maxAngularCorrection = 8.0f / 180.0f * b2_pi;			// 8 degrees

/// 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.
const float32 b2_contactBaumgarte = 0.2f;

// Sleep

/// The time that a body must be still before it will go to sleep.
const float32 b2_timeToSleep = 0.5f;									// half a second

/// A body cannot sleep if its linear velocity is above this tolerance.
const float32 b2_linearSleepTolerance = 0.01f;		// 1 cm/s

/// A body cannot sleep if its angular velocity is above this tolerance.
const float32 b2_angularSleepTolerance = 2.0f / 180.0f * b2_pi;		// 2 degrees/s

// Memory Allocation

/// The current number of bytes allocated through b2Alloc.
extern int32 b2_byteCount;

/// 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