Box2D Forums

//Body creation
b2Body* Game::create_body(b2Vec2 position, float rotation, float mass, float size)
{
   //Define body
   b2BodyDef bodyDef;
   //Properties
   bodyDef.position.Set(position.x, position.y);  //body's position
   bodyDef.angle = rotation * b2_pi; //body's angle in radians(?)
   bodyDef.massData.mass = 2.0; //body's mass in kg
   //Defaults
   bodyDef.massData.center.SetZero(); //center of mass in local coordinates
   bodyDef.massData.I = 3.0f; //rotational inertia in kg*m^2
   bodyDef.linearDamping = 0.0;
   bodyDef.angularDamping = 0.01f;
   bodyDef.allowSleep = true;
   bodyDef.isSleeping = false;
   bodyDef.isBullet = false;
   //Create body
   b2Body* body = world->CreateBody(&bodyDef);

   //Define shape
   b2CircleDef shapeDef;
   //Properties
   shapeDef.restitution = 1.0f;
   shapeDef.radius = 1.0f;
   shapeDef.localPosition.SetZero();
   //Default
   shapeDef.density = 1.0f;
   shapeDef.friction = 0.3f;
   //Create shape
   body->CreateShape(&shapeDef);
   body->SetMassFromShapes();

   return body;
}
//Body creation call
void Game::create_ship(b2Vec2 position, float rotation)
{
   Object *object_pointer = new Ship(*application);
   object_pointer->object_body = create_body(position, rotation, 3.0f, 1.5f);

   add_queue.push_back(object_pointer);
}
//Drawing function
void Direct3D::draw_sprite(Object &object)
{
   SpriteInstance sprite_instance = object.get_sprite_instance();
   LPDIRECT3DTEXTURE9 texture = sprite_instance.get_sprite()->get_texture();
   
   D3DXVECTOR2 scaling = get_scaling();
   D3DXVECTOR2 center = get_center((float)sprite_instance.get_size() / 2);

   float rotation = object.object_body->GetAngle();
   D3DXVECTOR2 position;
   position.x = object.object_body->GetPosition().x;
   position.y = object.object_body->GetPosition().y;

   RECT frame = get_frame(sprite_instance);

   D3DXMATRIX mat;
   D3DXMatrixTransformation2D(&mat,
                        NULL,
                        NULL,
                        &scaling,
                        &center,
                        rotation,
                        &position);
   
   d3d_sprite->SetTransform(&mat);
    d3d_sprite->Draw(texture, &frame, NULL, NULL, 0xFFFFFFFF);
}
//Move function
void Object::move(float magnitude)
{
   b2Vec2 direction;
   direction.x = sin(-object_body->GetAngle()) * magnitude;
   direction.y = cos(-object_body->GetAngle()) * magnitude;

   object_body->WakeUp();
   object_body->ApplyForce(direction, object_body->GetPosition());
}

//Object update function
void Ship::update(Game &game)
{
   if(game.get_application()->input.is_down(MOVE_FORWARD))
   {
      move(-200);
   }

}