CODEWITHSUNDEEP
c++functionclassprogram-entry-pointsfml
Jqmfg
Jqmfg

Reputation: 141

SFML Drawing a Moving Sprite in Another Class

I am fairly new to SFML and am trying to make a scrolling plane game that shoots out a bullet whenever I press the spacebar. I've gotten all of the movement working, but I'm trying to figure out how to put the bullets into another class file so that I can have a whole set of them later on (I.E. create.bullet(), create.missle(), etc.). Here is the code that I have now.

void create::bullet(int xPos, int yPos)
{
sf::Texture bulletTexture;
if(!bulletTexture.loadFromFile("bullet.png"))
    cout << "There was an error loading the bullet texture file." << endl;
sf::Sprite bulletSprite;
bulletSprite.setTexture(bulletTexture);
bulletSprite.setPosition(xPos, yPos);

window.draw(bulletSprite);

}

I have the sf::RenderWindow instance called window in the main class, but I apparently can't reference it directly from another class. I haven't been able to implement velocity yet either, but I should be able to do that. Another thing that I need help with however, is getting it so that there is no limit on the number of bullets that can be fired. It seems like if I just have this function run whenever spacebar is pressed, it will just reset the sprite to the new position and get rid of the old one. Thanks for the help!

Upvotes: 1

Views: 2804

Answers (1)

Adrian17
Adrian17

Reputation: 443

First of all, loading textures from files is slow. You should do it once when the program or level starts, and store the texture somewhere.

Instead of a Create class, make a Bullet class. Then, you can have a vector of bullets (or pointers/smart pointers to them). Each time you want a new bullet, you just push_back() it to the vector. If a bullet needs to be destroyed you erase() it. Then, for the game itself, you need to call Move() for every bullet and then Draw() for every bullet in the vector. Once you have that done, you can add the collision detection and so on.

You also have a choice - each bullet can have its own sf::sprite and modify it, or you can have one sf::sprite for each game sprite and reposition it for every bullet. Personally, I'm using the second approach. My Bullet class looks like this:

Bullet::Bullet(std::string ntype, double nx, double ny, double nvx, double nvy):
    type(ntype), x(nx), y(ny), vx(nvx), vy(nvy)
{
    angle=atan2(vy, vx)*(180/M_PI);
}
void Bullet::Move()
{
    x+=vx;
    y+=vy;
};
void Bullet::Draw()
{
    DrawSprite(type, x, y, angle+90);
};

In the separate .cpp file, I have a string ordered map of sf::sprites. My draw function looks like this:

void DrawSprite(std::string type, float x, float y, float angle)
{
    sf::Sprite temp=sprites[type];
    temp.setRotation(angle);
    temp.setPosition(x, y);
    window.draw(temp);
}

Upvotes: 1

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