static struct cpShapeMassInfo
cpSegmentShapeMassInfo(cpFloat mass, cpVect a, cpVect b, cpFloat r)
{
struct cpShapeMassInfo info = {
mass, cpMomentForBox(1.0f, cpvdist(a, b) + 2.0f*r, 2.0f*r), // TODO is an approximation.
cpvlerp(a, b, 0.5f),
cpAreaForSegment(a, b, r),
};
return info;
}
static cpBody *utils_update_drawing(cpBody *drawing) {
cpFloat mass = cpBodyGetMass(drawing);
cpFloat moment = cpBodyGetMoment(drawing);
Body_data *pa = cpBodyGetUserData(drawing);
//cpFloat x = g_array_index(pa->x_values, cpFloat, 0);
//cpFloat y = g_array_index(pa->y_values, cpFloat, 0);
cpVect pos_a, pos_b;
cpVect origin = cpBodyGetPos(drawing);
cpFloat mi, micx = 0, micy = 0;
int length = pa->x_values->len;
for (int index = 1; index < length; index++) {
pos_a = cpv(g_array_index(pa->x_values, cpFloat, index - 1), g_array_index(pa->y_values, cpFloat, index - 1));
pos_b = cpv(g_array_index(pa->x_values, cpFloat, index), g_array_index(pa->y_values, cpFloat, index));
//fprintf(stdout, "Pos_a = (%5.2f, %5.2f)\n", pos_a.x, pos_a.y);
mi = (CRAYON_MASS * cpAreaForSegment( pos_a, pos_b, CRAYON_RADIUS ));
micx += mi * ((pos_a.x + pos_b.x) / 2);
micy += mi * ((pos_a.y + pos_b.y) / 2);
mass += mi;
moment += cpMomentForSegment(mass, pos_a, pos_b); // not actually sum, but maybe it is
}
cpBodySetMass(drawing, mass);
cpBodySetMoment(drawing, moment);
// center of mass is the average of all vertices NOT
//cpVect new_origin = cpv(x / length, y / length);
cpVect new_origin = cpv(micx / mass, micy / mass);
new_origin = cpBodyLocal2World(drawing, new_origin);
cpBodySetPos( drawing, new_origin );
//fprintf(stdout, "Position set at (%5.2f, %5.2f)\n", new_origin.x, new_origin.y);
cpSpace * space = cpBodyGetSpace(drawing);
cpSpaceReindexShapesForBody(space, drawing);
//cpBodySetPos(drawing, cpv(pos.x + (second.x / length), pos.y + (second.y / length)));
//pa->offset = cpvsub(new_origin, origin);
pa = shift_origin(drawing, origin, new_origin);
cpBodySetUserData(drawing, pa);
if (space)
post_step_body_replace_shapes(space, drawing, NULL);
else
fprintf(stderr, "WTF\n");
//if (!(cpSpaceAddPostStepCallback(space, (cpPostStepFunc) post_step_body_replace_shapes, drawing, NULL)))
//fprintf(stderr, "FAILED POST-STEP CALLBACK\n\n");
return drawing;
}
/** @name areaForSegment
@text Returns the area for the specified segment.
@in number x1
@in number y1
@in number x2
@in number y2
@in number r
@out number area The calculated area.
*/
int MOAICpShape::_areaForSegment ( lua_State* L ) {
USLuaState state ( L );
if ( !state.CheckParams ( 1, "UUNNNN" )) return 0;
cpVect a;
a.x = state.GetValue < cpFloat >( 1, 0 );
a.y = state.GetValue < cpFloat >( 2, 0 );
cpVect b;
b.x = state.GetValue < cpFloat >( 3, 0 );
b.y = state.GetValue < cpFloat >( 4, 0 );
cpFloat r = state.GetValue < cpFloat >( 5, 0 );
lua_pushnumber ( L, cpAreaForSegment ( a, b, r ));
return 1;
}
static cpBody *utils_update_drawing(cpBody *drawing) {
cpFloat mass = cpBodyGetMass(drawing);
cpFloat moment = cpBodyGetMoment(drawing);
Point_array *pa = cpBodyGetUserData(drawing);
cpFloat x = g_array_index(pa->x_values, cpFloat, 0);
cpFloat y = g_array_index(pa->y_values, cpFloat, 0);
cpVect pos_a, pos_b;
cpVect origin = cpBodyGetPos(drawing);
cpFloat mi, micx = 0, micy = 0;
int length = pa->x_values->len;
for (int index = 1; index < length; index++) {
pos_a = cpv(g_array_index(pa->x_values, cpFloat, index - 1), g_array_index(pa->y_values, cpFloat, index - 1));
pos_b = cpv(g_array_index(pa->x_values, cpFloat, index), g_array_index(pa->y_values, cpFloat, index));
cpvadd(pos_a, origin);
cpvadd(pos_b, origin);
x += pos_b.x;
y += pos_b.y;
mi = (CRAYON_MASS * cpAreaForSegment( pos_a, pos_b, CRAYON_RADIUS ));
micx += mi * ((pos_a.x + pos_b.x) / 2);
micy += mi * ((pos_a.y + pos_b.y) / 2);
mass += mi;
moment += cpMomentForSegment(mass, pos_a, pos_b); // not actually sum
}
cpBodySetMass(drawing, mass);
cpBodySetMoment(drawing, moment);
// center of mass is the average of all vertices NOT
//cpVect new_origin = cpv(x / length, y / length);
cpVect new_origin = cpv(micx / mass, micy / mass);
cpBodySetPos( drawing, new_origin );
//cpBodySetPos(drawing, cpv(pos.x + (second.x / length), pos.y + (second.y / length)));
pa = shift_origin(pa, origin, new_origin);
cpBodySetUserData(drawing, pa);
return drawing;
}
cpFloat Area::ForSegment( cVect a, cVect b, cpFloat r ) {
return cpAreaForSegment( tocpv( a ), tocpv( b ), r );
}
__declspec( dllexport ) void areaforsegment( const void * _in, int in_size, void * _out, int out_sz )
{
POKEFLOAT(OUTPUT_MEMBLOCK,0,cpAreaForSegment(PEEKVECT(INPUT_MEMBLOCK,0),PEEKVECT(INPUT_MEMBLOCK,8),PEEKFLOAT(INPUT_MEMBLOCK,16)));
}
static VALUE
rb_cpAreaForSegment(VALUE self, VALUE v1, VALUE v2, VALUE r) {
cpFloat i = cpAreaForSegment(*VGET(v1), *VGET(v2), NUM2DBL(r));
return rb_float_new(i);
}
