b2Shape* Kolf::LineShape::createShape()
{
b2EdgeShape* shape = new b2EdgeShape;
shape->Set(
toB2Vec2(m_line.p1() * Kolf::Box2DScaleFactor),
toB2Vec2(m_line.p2() * Kolf::Box2DScaleFactor)
);
return shape;
}
void TiledMap::setPosition(osg::Vec3 position)
{
transformNode->setPosition(position);
for(int i = 0; i < physicsBodies.size(); ++i)
physicsBodies[i]->SetTransform(toB2Vec2(position), physicsBodies[i]->GetAngle());
}
b2Shape* Kolf::EllipseShape::createShape()
{
const b2Vec2 c = toB2Vec2(m_rect.center() * Kolf::Box2DScaleFactor);
//ensure some minimum size because b2PolygonShape gets confused when its
//area is smaller than FLT_EPSILON (TODO: handle rx*ry == 0 differently?)
const qreal rx = qMax(qreal(m_rect.width() * Kolf::Box2DScaleFactor / 2), qreal(1e-5));
const qreal ry = qMax(qreal(m_rect.height() * Kolf::Box2DScaleFactor / 2), qreal(1e-5));
if (rx == ry)
{
//use circle shape when possible because it's cheaper and exact
b2CircleShape* shape = new b2CircleShape;
shape->m_p = c;
shape->m_radius = rx;
return shape;
}
else
{
//elliptical shape is not pre-made in Box2D, so create a polygon instead
b2PolygonShape* shape = new b2PolygonShape;
static const int N = qMin(20, b2_maxPolygonVertices);
//increase N if the approximation turns out to be too bad
//TODO: calculate the (cos, sin) pairs only once
QVarLengthArray<b2Vec2, 20> vertices(N);
static const qreal angleStep = 2 * M_PI / N;
for (int i = 0; i < N; ++i)
{
const qreal angle = -i * angleStep; //CCW order as required by Box2D
vertices[i].x = c.x + rx * cos(angle);
vertices[i].y = c.y + ry * sin(angle);
}
shape->Set(vertices.data(), N);
return shape;
}
}
b2Shape* Kolf::RectShape::createShape()
{
b2PolygonShape* shape = new b2PolygonShape;
shape->SetAsBox(
m_rect.width() * Kolf::Box2DScaleFactor / 2,
m_rect.height() * Kolf::Box2DScaleFactor / 2,
toB2Vec2(m_rect.center() * Kolf::Box2DScaleFactor),
0 //intrinsic rotation angle
);
return shape;
}
