Topics

1

SFML projects / Flappy Bird fine clone

« on: June 26, 2022, 09:12:34 am »

Hello everyone 
  Today I want to share my development of a clone of the prestigious Flappy Bird.
It is nothing new and complex but this is my first finished and polished project.
So here is some information about the developer's side:

• I used Entity-Componen-System model for game structure. I don't know if it is an overkill, but ECS is definitely a strong tool.
• I also use sf::VertexArray instead of primitive shapes for drawing entities because I think it is more efficient 
• Then it took me a bit to realise I messed thing up because there is no call to rotate() for array. So what I did is using rotation matrix for rotating our bird (sounds overkill too  )
• Last but not least, the thing I enjoy most is shader and sf::RenderTexture usage. I used pixelate shader provided in SFML example package to create super cool transition inside menu.

Please go check the game out, too!
Thanks to SFML and C++ simplicity the game is really light.



Here is the link to download site: https://labg.itch.io/flappy-bird

2

General / A (possible) solution to rendering performance optimisation

« on: July 11, 2021, 08:28:31 am »

Hi guys. I have been using SFML for 2 months. As I learned the command queue system, I made a small test that you can move a tank. I decided to add accelerate each time unit, rather than keep velocity frame-independent.
The code looks like this:

void World::adaptEntityVelocity(Entity& entity, sf::Time dt)
{
    static constexpr float a = 500.0f;//acceleration
    static constexpr float msp = 400.0f;//max speed
    float velo = entity.getVelocity();
    //clamp velo to [-msp,msp]
    velo = std::min(msp, std::max(- msp, velo));
    if(velo > 0)
        entity.setVelocity(std::max(0.0f, velo - a * dt.asSeconds()));
    if(velo < 0)
        entity.setVelocity(std::min(0.0f, velo + a * dt.asSeconds()));
}
//...
adaptEntityVelocity(mPlayer, dt);
//...
mPlayer.move(mPlayer.getVelocity() * dt.asSeconds();

It worked just find until I use sf::RenderWindow::setFrameLimit(). It somehow makes the player moves slightly faster in 60 fps (compared to ~450 fps without setting limit) and crazily fast in 10fps. I think the problem is the time Game::update() and Game::processInput() system is also affected by setFrameLimit(). So I decided not to use setFrameLimit(), but I don’t want to let the game run as fast as possible because that hurts GPU. But if I only limit render frequency the CPU will run massively fast and consume lots of energy (same when you run an endless while() loop). Then I come up with an idea: limit Game::render() to 60 fps and game loop to 500fps. This is the code:

void Game::run()
{
    sf::Clock dtClock;
    sf::Time timeSinceLastFrame = sf::Time::Zero;
    while(mWindow.isOpen())
    {
        sf::Time elapsed = dtClock.restart();
        //limit loops per second;
        if (elapsed < sf::seconds(0.002f))
        {
            sf::sleep(sf::seconds(0.002f) - elapsed);
            elapsed += dtClock.restart();
        }
        timeSinceLastFrame += elapsed;
        while(timeSinceLastFrame >= TIMEPERFRAME)
        {
            timeSinceLastFrame -= TIMEPERFRAME;
            processInput();
            update(TIMEPERFRAME);
        }
        updateStat(elapsed);
        render(elapsed); // pass a time variable to count and set limit
    }
}

Render function:

void Game::render(sf::Time dt)
{
    mRenderTime += dt;
    if(mRenderTime >= sf::seconds(1.0f / 60.0f))
    {
        mRenderCount ++;
        mRenderTime -= sf::seconds(1.0f / 60.0f);

        mWindow.clear(sf::Color(0x00000000ff));

        mWorld.draw();

        mWindow.setView(mWindow.getDefaultView());
        mWindow.draw(mStatistics);
        mWindow.display();
    }
}
 

So what I want to know is would this work on any OP with various speed? Or is it just in my own laptop?

P/s: this is what I got after all: a decent render rate and a limited loops per frame

3

Graphics / Undefined reference to ResourceHolder when following "SFML Game development"

« on: June 22, 2021, 04:20:55 pm »

Hello everyone. I am currently using Code::Block 20.03 and C++ 17.I have been using SFML for nearly 3 months. I found Laurent's book "SFML Game Development" one week ago. So in page 63 there is code lines look like this:
"
     Aircraft::Aircraft(Type type, const TextureHolder& textures):
     mType(type), mSprite(textures.get(toTextureID(type)))
     {
     }
"
I made console project, linked to SFML library.
I use .hpp files for headers and .cpp files for either main or class function definitions, I do not use .inl files.
But as soon as I compile it said
"
     D:\2.Tin\Project\Plane_shooter\Aicraft.cpp|20|undefined reference to `ResourceHolder<sf::Texture,
     Textures::ID>::get(Textures::ID) const'|
     ||error: ld returned 1 exit status|
"
This is in the file "Aircraft.cpp". Following are #include of the files:
Aircraft.cpp : #include "Aircraft.hpp"
Aircraft.hpp : #include "ResourceHolder.hpp" (template class for storing resources such as fonts, textures, ... It has a public member function "template <typename Resource, typename Identifier> const Resource& get(Identifier id) const"
                    #include "ResourceIdentifiers.hpp" (which consists a namespace Textures {enum class ID{...} };
Can you help me? I do not think i can figure out the problem myself.
Im sorry i uploaded this post in general but i think its just something to do with graphics module since I have not dealt with others.
Any help and comment would be appreciated, thank you.