Day 135: Placing Tiles Two

Hello friends,

Today I completed some of the logic to allow me to place tiles on the map.

How It Works

// MouseTile.cpp
bool MouseTile::IsMouseClickedOnTile
(
     sf::Vector2f& tilePosition, 
     sf::Vector2i& gridPosition, 
     const sf::Vector2f& mousePosition
) const 
{
    if (sf::Mouse::isButtonPressed(sf::Mouse::Left))
    {
        tilePosition = m_tilePosition; 
        gridPosition = m_tileGridPosition;
        return true;
    }
    return false;
}

// Map.cpp
void Map::Update(double deltaTime, const sf::Vector2f& mousePosition)
{
    sf::Vector2f tilePosition;
    sf::Vector2i gridPosition;

    if (m_mouseTile.IsMouseClickedOnTile(tilePosition, gridPosition, mousePosition))
    {
        int i = gridPosition.x + gridPosition.y * m_grid.GetTotalCells().x;
        m_mapSprites[i] = m_mouseTile.GetSprite();
    }
}

So let's break this down a bit. The first block of code is the MouseTile file. In addition to the boilerplate Initialize, Load, Update, and Draw functions, I've added a third: IsMouseClickedOnTile. Which essentially waits until the tile is clicked, before sending a few variables to the Map file.

Next the Map file will wait for the function to be true before placing the clicked tile on the cell. Easy as that.

The main point of confusion and headache is how variables are being passed around in this tutorial. As much as I enjoy it the speaker can at times be all over the place and I'm not sure what's right and what's wrong. One thing I assume is good is to pass most variables around by reference. Thus saving space as we're not creating copies of everything. I'll show an example of that here:

int amount = 5;

int timesTwo(int number)
{
    return number * 2;
}

In this situation if I wanted to use the function I would have to save it in a variable:

amount = timesTwo(amount);

Which is a bit annoying since I'd like to just call the function and have the amount variable change. If that's my desired outcome I can do it this way.

int amount = 5;

void timesTwo(int& number)
{
    number *= 2;
}

timesTwo(amount);

This gives me the same outcome, but I'm not passing in "amount" as a reference. So when timesTwo executes, it literally takes "amount" at it's address, and modifies it. This is used very often throughout the project in order to better improve speed and space efficiency.

Thank you for reading today's blog, until tomorrow.