Messages

46

General discussions / Re: SFML Game Development -- A book on SFML

« on: November 30, 2013, 04:37:50 pm »

The diagram you used to demonstrate the flow of commands in Ch 4 was very helpful.  It's what made me realize it be really helpful to have a visual representation of classes and their interactions.  That got me wondering whether there was an popularized convention for diagramming different aspects of code?

Also, could you respond to the std::placeholders question?  I looked up a number of references, but still don't understand why a placeholder is being set for a function that doesn't have a parameter.

47

General discussions / Re: SFML Game Development -- A book on SFML

« on: November 30, 2013, 01:27:08 pm »

I have a few questions related to the book.

First, I am looking for a way to draw/visualize the systems used in the book.  For example, I have read and reread how commands are applied to the SceneGraph.  However, I just keep forgetting how they interact and this is true of a number of systems.  I need a technique to draw the interactions, so I can reference them now and then until they sink in.  Do you have any recommendations for this type of approach?

Next, I have a couple c++ 11 questions. 

In the following snippet of code why is this needed in the capture list?  Is it so createProjectile is in scope?

mMissileCommand.action   = [this, &textures] (SceneNode& node, sf::Time)
{
   createProjectile(node, Projectile::Missile, 0.f, 0.5, textures);
};

Why is the std::placeholders::_1 used here, when the increaseSpread function takes zero parameters.

data[Pickup::FireSpread].action = std::bind(&Aircraft::increaseSpread, _1);

void Aircraft::increaseSpread()
{
   if (mSpreadLevel < 3)
      ++mSpreadLevel;
}

Finally, here's a small correction I noticed in chapter 7 under the subtitle Displaying Text.  The author mentions the method Aircraft::update when they meant Aircraft::updateTexts. 

In the method Aircraft::update(), we check for the current hitpoints, and convert them to a string, using our custom toString() function.

48

General discussions / Re: SFML Game Development -- A book on SFML

« on: October 28, 2013, 06:00:13 pm »

I'm having an issue understanding the syntax of the derivedAction function.  Using std::function is new to me and is the crux of the issue.  I have included the entire function at the bottom.

std::function<void(SceneNode&, sf::Time)> derivedAction(Function fn)
 

The "std::function<void(SceneNode&, sf::Time)>" specifies the signature for the function derivedAction takes as a parameter.  However, this doesn't seem to jive with the examples from http://en.cppreference.com/w/cpp/utility/functional/function.  My understanding is that it should be specifying the signature for derivedAction.

moveLeft.action = derivedAction<Aircraft>(AircraftMover(-playerSpeed, 0.f));
 

I'm confused with the use of "<Aircraft>". 

template <typename GameObject, typename Function>
std::function<void(SceneNode&, sf::Time)> derivedAction(Function fn)
{
        return [=] (SceneNode& node, sf:Time dt)
        {
                // Check if cast is safe
                assert(dynamic_cast<GameObject*>(&node) != nullptr);

                // Downcast node and invoke function on it
                fn(static_cast<GameObject&>(node), dt)
        };
}
 

49

General discussions / Re: SFML Game Development -- A book on SFML

« on: October 28, 2013, 02:57:01 pm »

As I read the book I find myself wanting to ask a few questions.  Is there a forum or appropriate place to discuss aspects of the book?

50

General discussions / Re: SFML Game Development -- A book on SFML

« on: October 11, 2013, 04:58:15 pm »

I pulled down the SFML-Game-Development-Book repository and I was able to successfully build all the projects with VC++11.  Chapter 7 now runs successfully.

Chapters 8-10 load into the menus, but when I press the "play" button the game crashes.

I am about a quarter into the book and enjoying it.

51

General discussions / Re: SFML Game Development -- A book on SFML

« on: October 08, 2013, 12:06:08 pm »

I am having an issue compiling chapters 7-10.  I read through the thread and saw a few others were affected.  The solution Groogy provides at the bottom of page 6 does not work for me and I see no one else confirming the workaround for VC++11 users.

To be clear I receive the following errors when compiling chapters 7-10.

error C2100: illegal indirection

and

error C3849: function-style call on an expression of type 'const std::_Bind<_Forced,_Ret,_Fun,_V0_t,_V1_t,_V2_t,_V3_t,_V4_t,_V5_t,<unnamed-symbol>>' would lose const and/or volatile qualifiers for all 2 available operator overloads

I verify there are no additional changes in the repository on GitHub for "SFML-Game-Development-Book / 07_Gameplay / Source /".  I then make the one line change Groogy suggests in DataTables.cpp at the end of page 6.

data[Pickup::HealthRefill].action = [] (Aircraft& a) { a.repair(25); };

The error about indirection is gone, but I still receive the following error.

error C3849: function-style call on an expression of type 'const std::_Bind<_Forced,_Ret,_Fun,_V0_t,_V1_t,_V2_t,_V3_t,_V4_t,_V5_t,<unnamed-symbol>>' would lose const and/or volatile qualifiers for all 2 available operator overloads