Moving sprite objects of a class from within another class

[owenmin]

I'm making a base class for re-use in future projects. Basically a template that i could copy and paste to cut the initial time it takes to start a new project in SFML.

It's all working so far, and i can display my Player object's sprite to the screen. I added a function to my player class so that i can move the sprite around the screen by calling it from my base class, but when i do, it doesn't move. It draws from the base class but won't move when i call player->PlayerControl() from the base class.

Here's my code so you can see what i mean.

Main.cpp

#include <SFML/Graphics.hpp>
#include "Engine.h"

int main()
{
        Engine * engine = new Engine();

        engine->Go();

        return EXIT_SUCCESS;
}

Engine.cpp

void Engine::Go()
{
        if(!Init())
        {
                //Error here
        }
}

bool Engine::Init()
{
        window = new sf::RenderWindow(sf::VideoMode(800, 600, 32), "RPG game");
        window->setFramerateLimit(30);

        if(!window)
                return false;
        LoadImages();
        MainLoop();

        return true;
}

void Engine::LoadImages()
{
        sf::Texture playerTexture;
        playerTexture.loadFromFile("Link_front.png");

        imageManager.AddImage(playerTexture);

        player = new Player(imageManager.GetImage(0));
}

void Engine::MainLoop()
{
        while(window->isOpen())
        {
                ProcessInput();
                Update();
                RenderFrame();
        }
}

ProcessInput();

void Engine::ProcessInput()
{
        sf::Event Event;

        if(window->pollEvent(Event))
        {
                if(Event.type == sf::Event::Closed)
                        window->close();

                if(sf::Keyboard::isKeyPressed(sf::Keyboard::Escape))
                        window->close();
        }
        player->PlayerControl();
}

When i call player->PlayerControl(), nothing happens and the sprite doesn't move at all. Here is the Player.cpp move function:

void Player::PlayerControl()
{
        if(sf::Keyboard::isKeyPressed(sf::Keyboard::Up))
                playerSprite.move(0, -2.f);

        if(sf::Keyboard::isKeyPressed(sf::Keyboard::Down))
                playerSprite.move(0, 2.f);

        if(sf::Keyboard::isKeyPressed(sf::Keyboard::Left))
                playerSprite.move(-2.f, 0);

        if(sf::Keyboard::isKeyPressed(sf::Keyboard::Right))
                playerSprite.move(2.f, 0);
}

Sorry if this is hard to understand, it's not documented at all, but it should be simple enough to see what's going on as i have placed the functions in the order they are called so top from bottom is the way my game runs.

Why won't my sprite move when the function is called from ProcessInput() ?

[santiaboy]

Hm, I don't know what player.h is, so im guessing

maybe, just maybe, its because 2.f is a small number, so you can't see the difference, try 20 for example

[OniLinkPlus]

Hm, I don't know what player.h is, so im guessing

maybe, just maybe, its because 2.f is a small number, so you can't see the difference, try 20 for example

No, 2.f is two whole pixels, and this is per frame, from what I can tell, so that's not it.

Can you post a complete and minimal code that reproduces the problem so we can compile it and test it ourselves?

[owenmin]

Hm, I don't know what player.h is, so im guessing

maybe, just maybe, its because 2.f is a small number, so you can't see the difference, try 20 for example

No, 2.f is two whole pixels, and this is per frame, from what I can tell, so that's not it.

Can you post a complete and minimal code that reproduces the problem so we can compile it and test it ourselves?

https://gist.github.com/OwenMin/5244931

That's the full works right now, all you need to do is copy and paste them into the corresponding file names and it should compile.

EDIT: Oops, forgot to add my ImageManager, it's all functional now.

[OniLinkPlus]

Hm, I don't know what player.h is, so im guessing

maybe, just maybe, its because 2.f is a small number, so you can't see the difference, try 20 for example

No, 2.f is two whole pixels, and this is per frame, from what I can tell, so that's not it.

Can you post a complete and minimal code that reproduces the problem so we can compile it and test it ourselves?

https://gist.github.com/OwenMin/5244931

That's the full works right now, all you need to do is copy and paste them into the corresponding file names and it should compile.

EDIT: Oops, forgot to add my ImageManager, it's all functional now.

That is DEFINITELY not minimal. Minimal means cut out every single line of code that isn't relevant to the problem, and put it all into a SINGLE file. Preferably put it all into main() as well. For this problem, you definitely don't need all those classes to reproduce the problem.

I do, however, see what is most likely the cause of your problem. In Engine::ProcessInput(), you have these lines

if(window->pollEvent(Event))
        {
                if(Event.type == sf::Event::Closed)
                        window->close();
 
                if(sf::Keyboard::isKeyPressed(sf::Keyboard::Escape))
                        window->close();
        }
 

The problem here is that you say if(window->pollEvent(Event)). That won't work. That will only catch one event per frame, meaning any other events will get "backlogged" and not make it to the game for a long time. Since the keyboard state is updated by pollEvent, that means that your if statements won't know that the keyboard has been pressed until the keypress events get out of the backlog. If you want to fix this, you just need to change the if(window->pollEvent(Event)) to while(window->pollEvent(Event)).