b2BodyDef groundBodyDef;
groundBodyDef.position.Set(0, 0); // bottom-left corner


b2Body* groundBody = world->CreateBody(&groundBodyDef);

// Define the ground box shape.
b2PolygonShape groundBox;




// bottom
groundBox.SetAsEdge(b2Vec2(812.0/PTM_RATIO,310.0/PTM_RATIO), b2Vec2(-149.0/PTM_RATIO,310.0/PTM_RATIO));
groundBody->CreateFixture(&groundBox,0);