Convex Moment

cpConvexMoment.c

// This is a little annoying:
cpVect *hullVerts = (cpVect *)calloc(NUM_VERTS, sizeof(cpVect));
int hullCount = cpConvexHull(NUM_VERTS, verts, hullVerts, NULL, 0.0);

cpFloat mass = 1.0;
cpFloat moment = cpMomentForPoly(mass, hullCount, hullVerts, cpvzero);

body = cpSpaceAddBody(space, cpBodyNew(mass, moment));

shape = cpSpaceAddShape(space, cpPolyShapeNew(body, hullCount, hullVerts, cpvzero));

free(hullVerts);

// This isn't so bad:

CP_MAKE_CONVEX(NUM_VERTS, verts, hullCount, hullVerts);

cpFloat mass = 1.0;
cpFloat moment = cpMomentForPoly(mass, hullCount, hullVerts, cpvzero);

body = cpSpaceAddBody(space, cpBodyNew(mass, moment));

shape = cpSpaceAddShape(space, cpPolyShapeNew(body, hullCount, hullVerts, cpvzero));

// Using the following macro:

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