bool PhysicsShapePolygon::init(const Vec2* points, int count, const PhysicsMaterial& material/* = MaterialDefault*/, const Vec2& offset/* = Vec2(0, 0)*/, float radius/* = 0.0f*/)
{
do
{
_type = Type::POLYGEN;
auto vecs = new (std::nothrow) cpVect[count];
PhysicsHelper::points2cpvs(points, vecs, count); //count = cpConvexHull((int)count, vecs, nullptr, nullptr, 0);
cpTransform transform = cpTransformTranslate(PhysicsHelper::point2cpv(offset));
auto shape = cpPolyShapeNew(s_sharedBody, count, vecs, transform, radius);
CC_SAFE_DELETE_ARRAY(vecs);
CC_BREAK_IF(shape == nullptr);
cpShapeSetUserData(shape, this);
addShape(shape);
_area = calculateArea();
_mass = material.density == PHYSICS_INFINITY ? PHYSICS_INFINITY : material.density * _area;
_moment = calculateDefaultMoment();
setMaterial(material);
return true;
} while (false);
return false;
}
bool PhysicsShapeBox::init(const Size& size, const PhysicsMaterial& material/* = MaterialDefault*/, const Vec2& offset /*= Vec2(0, 0)*/, float radius/* = 0.0f*/)
{
do
{
_type = Type::BOX;
auto wh = PhysicsHelper::size2cpv(size);
cpVect vec[4] =
{
{-wh.x/2.0f, -wh.y/2.0f}, {-wh.x/2.0f, wh.y/2.0f}, {wh.x/2.0f, wh.y/2.0f}, {wh.x/2.0f, -wh.y/2.0f}
};
cpTransform transform = cpTransformTranslate(PhysicsHelper::point2cpv(offset));
auto shape = cpPolyShapeNew(s_sharedBody, 4, vec, transform, radius);
CC_BREAK_IF(shape == nullptr);
cpShapeSetUserData(shape, this);
addShape(shape);
_area = calculateArea();
_mass = material.density == PHYSICS_INFINITY ? PHYSICS_INFINITY : material.density * _area;
_moment = calculateDefaultMoment();
setMaterial(material);
return true;
} while (false);
return false;
}
/*
* Chipmunk2d::Transform.translate(vect)
* @param [Chipmunk2d::Vect] vect
* @return [Chipmunk2d::Transform]
*/
static mrb_value
transform_s_translate(mrb_state* mrb, mrb_value klass)
{
cpVect* vect;
mrb_get_args(mrb, "d", &vect, &mrb_cp_vect_type);
return mrb_cp_transform_value(mrb, cpTransformTranslate(*vect));
}
void Slice::ClipPoly(cpSpace *space, cpShape *shape, cpVect n, cpFloat dist)
{
cpBody *body = cpShapeGetBody(shape);
int count = cpPolyShapeGetCount(shape);
int clippedCount = 0;
cpVect *clipped = (cpVect *)alloca((count + 1)*sizeof(cpVect));
for(int i=0, j=count-1; i<count; j=i, i++){
cpVect a = cpBodyLocalToWorld(body, cpPolyShapeGetVert(shape, j));
cpFloat a_dist = cpvdot(a, n) - dist;
if(a_dist < 0.0){
clipped[clippedCount] = a;
clippedCount++;
}
cpVect b = cpBodyLocalToWorld(body, cpPolyShapeGetVert(shape, i));
cpFloat b_dist = cpvdot(b, n) - dist;
if(a_dist*b_dist < 0.0f){
cpFloat t = cpfabs(a_dist)/(cpfabs(a_dist) + cpfabs(b_dist));
clipped[clippedCount] = cpvlerp(a, b, t);
clippedCount++;
}
}
cpVect centroid = cpCentroidForPoly(clippedCount, clipped);
cpFloat mass = cpAreaForPoly(clippedCount, clipped, 0.0f)*DENSITY;
cpFloat moment = cpMomentForPoly(mass, clippedCount, clipped, cpvneg(centroid), 0.0f);
cpBody *new_body = cpSpaceAddBody(space, cpBodyNew(mass, moment));
cpBodySetPosition(new_body, centroid);
cpBodySetVelocity(new_body, cpBodyGetVelocityAtWorldPoint(body, centroid));
cpBodySetAngularVelocity(new_body, cpBodyGetAngularVelocity(body));
cpTransform transform = cpTransformTranslate(cpvneg(centroid));
cpShape *new_shape = cpSpaceAddShape(space, cpPolyShapeNew(new_body, clippedCount, clipped, transform, 0.0));
// Copy whatever properties you have set on the original shape that are important
cpShapeSetFriction(new_shape, cpShapeGetFriction(shape));
}
