Misc

Macros
#define	CP_BUFFER_BYTES   (32*1024)
	Allocated size for various Chipmunk buffers.
#define	cpcalloc   calloc
	Chipmunk calloc() alias.
#define	cprealloc   realloc
	Chipmunk realloc() alias.
#define	cpfree   free
	Chipmunk free() alias.
#define	CP_CONVEX_HULL(__count__, __verts__, __count_var__, __verts_var__)
	Convenience macro to work with cpConvexHull. More...

Functions
cpFloat	cpMomentForCircle (cpFloat m, cpFloat r1, cpFloat r2, cpVect offset)
	Calculate the moment of inertia for a circle. More...
cpFloat	cpAreaForCircle (cpFloat r1, cpFloat r2)
	Calculate area of a hollow circle. More...
cpFloat	cpMomentForSegment (cpFloat m, cpVect a, cpVect b, cpFloat radius)
	Calculate the moment of inertia for a line segment. More...
cpFloat	cpAreaForSegment (cpVect a, cpVect b, cpFloat radius)
	Calculate the area of a fattened (capsule shaped) line segment.
cpFloat	cpMomentForPoly (cpFloat m, int count, const cpVect *verts, cpVect offset, cpFloat radius)
	Calculate the moment of inertia for a solid polygon shape assuming it's center of gravity is at it's centroid. The offset is added to each vertex.
cpFloat	cpAreaForPoly (const int count, const cpVect *verts, cpFloat radius)
	Calculate the signed area of a polygon. More...
cpVect	cpCentroidForPoly (const int count, const cpVect *verts)
	Calculate the natural centroid of a polygon.
cpFloat	cpMomentForBox (cpFloat m, cpFloat width, cpFloat height)
	Calculate the moment of inertia for a solid box.
cpFloat	cpMomentForBox2 (cpFloat m, cpBB box)
	Calculate the moment of inertia for a solid box.
int	cpConvexHull (int count, const cpVect *verts, cpVect *result, int *first, cpFloat tol)
	Calculate the convex hull of a given set of points. More...
static cpVect	cpClosetPointOnSegment (const cpVect p, const cpVect a, const cpVect b)
	Returns the closest point on the line segment ab, to the point p.

Variables
const char *	cpVersionString
	Version string.

Detailed Description

Macro Definition Documentation

#define CP_CONVEX_HULL	(		__count__,
			__verts__,
			__count_var__,
			__verts_var__
	)

Value:

cpVect *__verts_var__ = (cpVect *)alloca(__count__*sizeof(cpVect)); \
int __count_var__ = cpConvexHull(__count__, __verts__, __verts_var__, NULL, 0.0); \

Convenience macro to work with cpConvexHull.

count and verts is the input array passed to cpConvexHull(). count_var and verts_var are the names of the variables the macro creates to store the result. The output vertex array is allocated on the stack using alloca() so it will be freed automatically, but cannot be returned from the current scope.

Function Documentation

cpFloat cpAreaForCircle	(	cpFloat	r1,
		cpFloat	r2
	)

Calculate area of a hollow circle.

r1 and r2 are the inner and outer diameters. A solid circle has an inner diameter of 0.

cpFloat cpAreaForPoly	(	const int	count,
		const cpVect *	verts,
		cpFloat	radius
	)

Calculate the signed area of a polygon.

A Clockwise winding gives positive area. This is probably backwards from what you expect, but matches Chipmunk's the winding for poly shapes.

int cpConvexHull	(	int	count,
		const cpVect *	verts,
		cpVect *	result,
		int *	first,
		cpFloat	tol
	)

Calculate the convex hull of a given set of points.

Returns the count of points in the hull. result must be a pointer to a cpVect array with at least count elements. If verts == result, then verts will be reduced inplace. first is an optional pointer to an integer to store where the first vertex in the hull came from (i.e. verts[first] == result[0]) tol is the allowed amount to shrink the hull when simplifying it. A tolerance of 0.0 creates an exact hull.

cpFloat cpMomentForCircle	(	cpFloat	m,
		cpFloat	r1,
		cpFloat	r2,
		cpVect	offset
	)

Calculate the moment of inertia for a circle.

r1 and r2 are the inner and outer diameters. A solid circle has an inner diameter of 0.

cpFloat cpMomentForSegment	(	cpFloat	m,
		cpVect	a,
		cpVect	b,
		cpFloat	radius
	)

Calculate the moment of inertia for a line segment.

Beveling radius is not supported.