C++ Sfml delete single Object from vector - c++

Question

i try to making a little game in SFML (C++) So i have a simple Problem with pick up an object by a player. The object is in a vector, i have to objects on the screen and when the player intersect(Collision) with them they have to erase. But still booth objects erase when the player intersect with a single object, how i can fix ?
so my question is: How can i erase (or delete) a single object from a vector who is collide with a player?
here is my code
RectangleShape object;
std::vector<RectangleShape> objects(3);
RectangleShape player;
...
while (window.isOpen())
{
sf::Event event;
while (window.pollEvent(event));
...
for (int j = 0; j < objects.size(); j++){
objects[j].setFillColor(Color::Cyan);
objects[1].setSize(Vector2f(100, 100));
objects[1].setPosition(Vector2f(650, 1000));
objects[2].setSize(Vector2f(100, 100));
objects[2].setPosition(Vector2f(650, 700));
}
for (auto& object: objects){
FloatRect playerBounds = player.getGlobalBounds();
FloatRect objectBounds = object.getGlobalBounds();
for ( auto it = objects.begin(); it != objects.end();)
{
if(objectBounds. intersects(playerBounds)) {
it = objects.erase(it);
}
else
{
++it;
}
window.draw(objects[1]);
window.draw(objects[2]);
}
}

Answer 1

I tried to keep as much from your code as it was possible so you could see the difference, not the whole different code. The reason why your code wasn't deleting just one obj. and every single is that your loops weren't correctly written.
See this:
for (auto& object: objects){ //iterating through objects
FloatRect playerBounds = player.getGlobalBounds();
FloatRect objectBounds = object.getGlobalBounds(); //<- this *1*
for ( auto it = objects.begin(); it != objects.end();) //iterating through every single one AGAIN
{
if(objectBounds. intersects(playerBounds)) { //what this if does is that it check if this *1* obj. intersects with your player
it = objects.erase(it); //however it doesn't particularly erase that *1* obj., it just erases every obj. in the vector, because when that if is true it will iterate through the vector and delete one by one.
}
else
{
++it;
}
}
The main problem is that 2nd iteration for ( auto it = objects.begin(); it != objects.end();) and if in it are 2 separate things.
There are many solutions to make it work, but then it would be just adding more code to make more spaghetti, so just redo it to make it better.
Here is the working ver:
RectangleShape object;// not needed
std::vector<RectangleShape> objects(3);
for (int j = 0; j < objects.size(); j++) {
objects[j].setFillColor(Color::Cyan);
objects[j].setSize(Vector2f(100, 100));
objects[j].setPosition(Vector2f(650, 1000 - j * 300)); //just a quick way to set position of "every" to be 1000, 700, 400 etc.
//objects[1].setSize(Vector2f(100, 100));
//objects[1].setPosition(Vector2f(650, 1000)); // shouldn't set the obj[1] parameters withing loop since you are setting them the n times where n is number of objs. in the vector
//objects[2].setSize(Vector2f(100, 100));
//objects[2].setPosition(Vector2f(650, 700));//and you should just delete it from there
}
RectangleShape player;
player.setSize(Vector2f(100, 100));
player.setPosition(Vector2f(650, 1000)); //setting player parameters separately since it is not in the vector
// Also I moved making and setting of player and other obj in the vector out of the game loop so it won't be creating them every single frame
while (window.isOpen())
{
sf::Event event;
while (window.pollEvent(event));
...
for (auto it = objects.begin(); it != objects.end();) {
FloatRect playerBounds = player.getGlobalBounds();
FloatRect objectBounds = it->getGlobalBounds(); //iterator is just similar to a pointer, so to access what it points to you need to use "->" or "*" instead of "."
if (objectBounds.intersects(playerBounds)) {
it = objects.erase(it);
}
else
it++;
}
for (auto& object : objects) { //drawing every single obj. in the vector
window.draw(object);
}
window.draw(player); //drawing player separately since it is not in the vector
}
For the tutorial part that you mentioned in the comments, I would recommend you checking ones from sfml site since they not only contain descriptions of methods, etc. but also demo code.