Unmaintained Introduction to coding - 13. Buying and using potions

Buying and using potions​

Obtaining gold​

Until now, there was no mean for the player to obtain gold. We will give the character a gold coin for each monster slayed.

In the section of code executed when the player kills a monster, we will add the following code:

// Increases the amount of gold by 1.
playerGoldAmount++;
// Updates the gold count displayed.
goldAmountText.setString(std::to_string(playerGoldAmount));

Here is the whole 'if' structure:

if(monstersDead[c] == false && attackRect.intersects(monsters[c].getGlobalBounds()))
{
    monstersDead[c] = true;
    monsterRespawnClocks[c].restart();

    playerGoldAmount++;
    goldAmountText.setString(std::to_string(playerGoldAmount));
}

View attachment 624

Converting a number to text​

The following:

"123"

Is different than:

123

The former is a text composed of 3 characters and the latter is a number (numeric value) composed of 3 decimal digits.

To convert a number to a text, we can use the function std::to_string. That functions takes, in argument, a number and it returns a text representing that number. Note that in C++ (And in programming in general), a text is called a string (A string of characters).

std::to_string(567); // Returns "567".

int number = 202;
sf::Text text;
text.setString(to_string(number)); // The sf::Text object represents the text "202".

Buying potions​

When the window is focused and a key is pressed, it receives an event of type sf::Event::KeyPressed. In that case, the variable event.key.code equals the key that has been pressed.

Inside the event loop (Where the events are extracted from the window):

while(win.pollEvent(event))
{
    if(event.type == sf::Event::Closed)
        win.close();
}

We check if the type of the event is sf::Event::KeyPressed and if the player is alive:

else if(event.type == sf::Event::KeyPressed && playerHealthAmount > 0)

If so, we check if the key pressed is B and if the player is near the merchant:

if(event.key.code == sf::Keyboard::B && isPlayerNearMerchant)

If the condition above is true, we verify that the player has more than 1 gold coin (A potion costs 2 coins):

if(playerGoldAmount > 1)

If the player has enough money, we buy a potion (Subtract 2 coins from its gold amount, increase its amount of potions by one and update the potion icon and the text displaying the gold/potion amount).

playerGoldAmount -= 2;
playerPotionAmount += 1;

goldAmountText.setString(std::to_string(playerGoldAmount));
potionAmountText.setString(std::to_string(playerPotionAmount));
// If the icon used was the empty vial one, it replaces it by the one showing a filled potion.
potion.setTexture(healthPotionTex);

Using the potions​

When we extract an event of type sf::Event::KeyPressed from the window, we check if the key that was pressed is P:

else if(event.key.code == sf::Keyboard::P)

If so, we verify that the player has potions and that his health is not full:

if(playerPotionAmount > 0 && playerHealthAmount < 3)

If this is the case, we increase the health of the player by one, reduce its count of potions by 1 and update the amount of potions displayed and the potion/hearts icons.

playerHealthAmount++;
playerPotionAmount--;
potionAmountText.setString(std::to_string(playerPotionAmount));

// If the player has no potion, we display an empty vial.
if(playerPotionAmount == 0)
    potion.setTexture(emptyVialTex);

// We 'fill' the first empty heart icon.
if(playerHealthAmount == 2)
    hearts[1].setTexture(heartTex);
else if(playerHealthAmount == 3)
    hearts[2].setTexture(heartTex);

View attachment 625

Displaying a message at the death of the player​

We will display a message when the player dies. Here we create the sf::Text object representing the text to display at the death of the character:

sf::Text deadText;
deadText.setFont(font);
deadText.setString("You are dead.");
deadText.setFillColor(sf::Color::White);
deadText.setCharacterSize(30);
// We place it at the middle of the window.
deadText.setPosition((800 - (deadText.getGlobalBounds().width)) / 2, (600 - (deadText.getGlobalBounds().height)) / 2);

If the player is dead (No health point left), we display the message:

if(playerHealthAmount <= 0)
    win.draw(deadText);

To stop the game from being updated once the player is dead (To prevent the player from moving, stop the animation/spawning of the monsters...), we place the code updating the game inside the following 'if' structure:

if(playerHealthAmount > 0)
{
}

View attachment 626

The code of the game so far​

#include <SFML/Graphics.hpp>

int main()
{
    sf::RenderWindow win(sf::VideoMode(800, 600), "Introduction to coding", sf::Style::Close);

    // Grass

    sf::Texture grassTex;
    grassTex.loadFromFile("resources/grass.png");
    grassTex.setRepeated(true);

    sf::Sprite grass;
    grass.setTexture(grassTex);
    grass.setScale(5, 5);
    grass.setTextureRect(sf::IntRect(0,0,160,120));

    // Dirt tiles

    sf::Texture dirtTex;
    dirtTex.loadFromFile("resources/dirt.png");

    sf::Sprite dirtTiles[10];
    dirtTiles[0].setPosition(300, 60);
    dirtTiles[1].setPosition(660, 300);
    dirtTiles[2].setPosition(390, 480);
    dirtTiles[3].setPosition(660, 60);
    dirtTiles[4].setPosition(720, 420);
    dirtTiles[5].setPosition(180, 300);
    dirtTiles[6].setPosition(60, 180);
    dirtTiles[7].setPosition(60, 420);
    dirtTiles[8].setPosition(240, 420);
    dirtTiles[9].setPosition(480, 120);

    for(int c = 0; c < 10; c++)
    {
        dirtTiles[c].setTexture(dirtTex);
        dirtTiles[c].setScale(5, 5);
    }

    // Trees

    sf::Texture treeTex;
    treeTex.loadFromFile("resources/tree.png");

    sf::Sprite trees[8];
    trees[0].setPosition(50, 60);
    trees[1].setPosition(600, 150);
    trees[2].setPosition(630, 456);
    trees[3].setPosition(300, 600);
    trees[4].setPosition(720, 40);
    trees[5].setPosition(460, 500);
    trees[6].setPosition(20, 370);
    trees[7].setPosition(340, 240);

    for(int c = 0; c < 8; c++)
    {
        trees[c].setTexture(treeTex);
        trees[c].setScale(3, 3);
    }

    // Stones

    sf::Texture stoneTex;
    stoneTex.loadFromFile("resources/stone.png");

    sf::Sprite stones[3];
    stones[0].setPosition(304, 64);
    stones[1].setPosition(664, 304);
    stones[2].setPosition(180, 300);

    for(int c = 0; c < 3; c++)
    {
        stones[c].setTexture(stoneTex);
        stones[c].setScale(3, 3);
    }

    // Player

    sf::Texture playerTex;
    playerTex.loadFromFile("resources/player.png");
    sf::Texture playerAttackingTex;
    playerAttackingTex.loadFromFile("resources/playerAttacking.png");

    sf::Sprite player;
    player.setTexture(playerTex);
    player.setPosition(400, 300);
    player.setScale(3, 3);

    float playerMovementSpeed = 200.0;
    sf::Clock playerMovementClock;
    sf::Clock playerAttackClock;

    int playerGoldAmount = 0, playerPotionAmount = 0, playerHealthAmount = 3;

    // Monsters

    sf::Texture monsterTexs[3];
    monsterTexs[0].loadFromFile("resources/monster1.png");
    monsterTexs[1].loadFromFile("resources/monster2.png");
    monsterTexs[2].loadFromFile("resources/monster3.png");

    sf::Sprite monsters[4];
    monsters[0].setPosition(500, 40);
    monsters[1].setPosition(100, 170);
    monsters[2].setPosition(400, 450);
    monsters[3].setPosition(690, 160);

    bool monstersDead[4];

    for(int c = 0; c < 4; c++)
    {
        monsters[c].setTexture(monsterTexs[0]);
        monsters[c].setScale(3, 3);
        monstersDead[c] = false;
    }

    sf::Clock monstersAnimationClock;
    sf::Clock monsterRespawnClocks[4];
    sf::Clock monsterAttackClock;
    bool isPlayerNearMonster = false;

    // Gold

    sf::Texture goldTex;
    goldTex.loadFromFile("resources/gold.png");

    sf::Sprite gold;
    gold.setTexture(goldTex);
    gold.setScale(2, 2);
    gold.setPosition(15, 10);

    sf::Font font;
    font.loadFromFile("resources/LinuxBiolinum.ttf");

    sf::Text goldAmountText;
    goldAmountText.setFont(font);
    goldAmountText.setString("0");
    goldAmountText.setFillColor(sf::Color::White);
    goldAmountText.setCharacterSize(24);
    goldAmountText.setPosition(60, 10);

    // Potions

    sf::Texture healthPotionTex;
    healthPotionTex.loadFromFile("resources/healthPotion.png");
    sf::Texture emptyVialTex;
    emptyVialTex.loadFromFile("resources/emptyVial.png");

    sf::Sprite potion;
    potion.setTexture(emptyVialTex);
    potion.setScale(2, 2);
    potion.setPosition(350, 10);

    sf::Text potionAmountText;
    potionAmountText.setFont(font);
    potionAmountText.setString("0");
    potionAmountText.setFillColor(sf::Color::White);
    potionAmountText.setCharacterSize(24);
    potionAmountText.setPosition(395, 10);

    // Health of the player

    sf::Texture heartTex;
    heartTex.loadFromFile("resources/heart.png");
    sf::Texture emptyHeartTex;
    emptyHeartTex.loadFromFile("resources/emptyHeart.png");

    sf::Sprite hearts[3];
    hearts[0].setPosition(800 - 130, 10);
    hearts[1].setPosition(800 - 90, 10);
    hearts[2].setPosition(800 - 50, 10);

    for(int c = 0; c < 3; c++)
    {
        hearts[c].setTexture(heartTex);
        hearts[c].setScale(2, 2);
    }

    // Castle

    sf::Texture castleTex;
    castleTex.loadFromFile("resources/castle.png");

    sf::Sprite castle;
    castle.setTexture(castleTex);
    castle.setScale(4, 4);
    castle.setPosition(40, 460);

    // Merchant

    sf::Texture merchantTex;
    merchantTex.loadFromFile("resources/merchant.png");

    sf::Sprite merchant;
    merchant.setTexture(merchantTex);
    merchant.setScale(3, 3);
    merchant.setPosition(77, 415);

    sf::Text buyPotionText;
    buyPotionText.setFont(font);
    buyPotionText.setString("Press B to buy a potion.");
    buyPotionText.setFillColor(sf::Color::White);
    buyPotionText.setCharacterSize(30);
    buyPotionText.setPosition((800 - (buyPotionText.getGlobalBounds().width)) / 2, (600 - (buyPotionText.getGlobalBounds().height)) / 2);

    bool isPlayerNearMerchant = false;

    // Message at the death of the player

    sf::Text deadText;
    deadText.setFont(font);
    deadText.setString("You are dead.");
    deadText.setFillColor(sf::Color::White);
    deadText.setCharacterSize(30);
    deadText.setPosition((800 - (deadText.getGlobalBounds().width)) / 2, (600 - (deadText.getGlobalBounds().height)) / 2);

    // Game loop

    sf::Event event;

    while(win.isOpen())
    {
        while(win.pollEvent(event))
        {
            if(event.type == sf::Event::Closed)
                win.close();
            else if(event.type == sf::Event::KeyPressed && playerHealthAmount > 0)
            {
                if(event.key.code == sf:⌨️:B && isPlayerNearMerchant)
                {
                    if(playerGoldAmount > 1)
                    {
                        playerGoldAmount -= 2;
                        playerPotionAmount += 1;

                        goldAmountText.setString(std::to_string(playerGoldAmount));
                        potionAmountText.setString(std::to_string(playerPotionAmount));
                        potion.setTexture(healthPotionTex);
                    }
                }
                else if(event.key.code == sf:⌨️:P)
                {
                    if(playerPotionAmount > 0 && playerHealthAmount < 3)
                    {
                        playerHealthAmount++;
                        playerPotionAmount--;
                        potionAmountText.setString(std::to_string(playerPotionAmount));

                        if(playerPotionAmount == 0)
                            potion.setTexture(emptyVialTex);

                        if(playerHealthAmount == 2)
                            hearts[1].setTexture(heartTex);
                        else if(playerHealthAmount == 3)
                            hearts[2].setTexture(heartTex);
                    }
                }
            }
        }

        if(playerHealthAmount > 0)
        {
            // Player movements

            sf::Vector2f trans;
            float mouv = playerMovementClock.getElapsedTime().asSeconds() * playerMovementSpeed;

            if(sf:⌨️:isKeyPressed(sf:⌨️:W))
                trans.y -= mouv;
            if(sf:⌨️:isKeyPressed(sf:⌨️:S))
                trans.y += mouv;
            if(sf:⌨️:isKeyPressed(sf:⌨️:A))
                trans.x -= mouv;
            if(sf:⌨️:isKeyPressed(sf:⌨️:D))
                trans.x += mouv;

            player.setPosition(player.getPosition().x+trans.x, player.getPosition().y+trans.y);
            playerMovementClock.restart();

            // Collision testing

            for(int c=0; c < 8; c++)
            {
                if(player.getGlobalBounds().intersects(trees[c].getGlobalBounds()))
                    player.setPosition(player.getPosition().x-trans.x, player.getPosition().y-trans.y);
            }
            for(int c=0; c < 3; c++)
            {
                if(player.getGlobalBounds().intersects(stones[c].getGlobalBounds()))
                    player.setPosition(player.getPosition().x-trans.x, player.getPosition().y-trans.y);
            }
            if(player.getGlobalBounds().intersects(castle.getGlobalBounds()))
                player.setPosition(player.getPosition().x-trans.x, player.getPosition().y-trans.y);
            if(player.getGlobalBounds().intersects(merchant.getGlobalBounds()))
                player.setPosition(player.getPosition().x-trans.x, player.getPosition().y-trans.y);

            // Animation of the monsters

            int index = monstersAnimationClock.getElapsedTime().asMilliseconds() / 333;

            if(index > 2)
            {
                monstersAnimationClock.restart();
                index = 0;
            }

            for(int c=0; c < 4; c++)
            {
                monsters[c].setTexture(monsterTexs[index]);
            }

            // Player attacking

            if((sf:⌨️:isKeyPressed(sf:⌨️:Space) || sf:🐭:isButtonPressed(sf:🐭:Left)) && playerAttackClock.getElapsedTime().asMilliseconds() > 1000)
            {
                playerAttackClock.restart();
                player.setTexture(playerAttackingTex);

                // Testing if the attack reaches a monster

                sf::FloatRect attackRect(player.getPosition()+sf::Vector2f((player.getGlobalBounds().width/4), -player.getGlobalBounds().height/3), sf::Vector2f(player.getGlobalBounds().width/4, player.getGlobalBounds().height/3));

                for(int c=0; c < 4; c++)
                {
                    if(monstersDead[c] == false && attackRect.intersects(monsters[c].getGlobalBounds()))
                    {
                        monstersDead[c] = true;
                        monsterRespawnClocks[c].restart();

                        playerGoldAmount++;
                        goldAmountText.setString(std::to_string(playerGoldAmount));
                    }
                }
            }

            if(playerAttackClock.getElapsedTime().asMilliseconds() > 1000)
                player.setTexture(playerTex);

            // Monster attacking

            bool isPlayerCurrentlyNearMonster = false;

            for(int c=0; c < 4; c++)
            {
                if(monstersDead[c] == false)
                {
                    sf::FloatRect nearMonsterRect(monsters[c].getGlobalBounds());
                    nearMonsterRect.left -= nearMonsterRect.width;
                    nearMonsterRect.top -= nearMonsterRect.height;
                    nearMonsterRect.width *= 3;
                    nearMonsterRect.height *= 3;

                    if(player.getGlobalBounds().intersects(nearMonsterRect))
                    {
                        isPlayerCurrentlyNearMonster = true;

                        if(isPlayerNearMonster)
                        {
                            if(monsterAttackClock.getElapsedTime().asSeconds() >= 1 && playerHealthAmount > 0)
                            {
                                playerHealthAmount--;
                                monsterAttackClock.restart();

                                if(playerHealthAmount == 0)
                                    hearts[0].setTexture(emptyHeartTex);
                                else if(playerHealthAmount == 1)
                                    hearts[1].setTexture(emptyHeartTex);
                                else
                                    hearts[2].setTexture(emptyHeartTex);
                            }
                        }
                        else
                        {
                            isPlayerNearMonster = true;
                            monsterAttackClock.restart();
                        }
                    }
                }
            }

            if(isPlayerCurrentlyNearMonster == false)
                isPlayerNearMonster = false;

            // Respawn of the monsters

            for(int c=0; c < 4; c++)
            {
                if(monsterRespawnClocks[c].getElapsedTime().asSeconds() >= 8)
                    monstersDead[c] = false;
            }

            // Checks if the player is near the merchant

            sf::FloatRect nearMerchantRect(merchant.getGlobalBounds());
            nearMerchantRect.left -= nearMerchantRect.width;
            nearMerchantRect.top -= nearMerchantRect.height;
            nearMerchantRect.width *= 3;
            nearMerchantRect.height *= 3;

            if(player.getGlobalBounds().intersects(nearMerchantRect))
                isPlayerNearMerchant = true;
            else
                isPlayerNearMerchant = false;
        }

        // [B]* Rendering *[/B]

        win.clear();

        // Floor

        win.draw(grass);

        for(int c = 0; c < 10; c++)
            win.draw(dirtTiles[c]);

        // Game objects

        for(int c = 0; c < 8; c++)
            win.draw(trees[c]);

        for(int c = 0; c < 3; c++)
            win.draw(stones[c]);

        win.draw(player);

        for(int c = 0; c < 4; c++)
        {
            if(monstersDead[c] == false)
                win.draw(monsters[c]);
        }

        win.draw(castle);
        win.draw(merchant);


        // Player information

        win.draw(gold);
        win.draw(goldAmountText);

        win.draw(potion);
        win.draw(potionAmountText);

        for(int c = 0; c < 3; c++)
            win.draw(hearts[c]);

        if(playerHealthAmount <= 0)
            win.draw(deadText);
        else if(isPlayerNearMerchant)
            win.draw(buyPotionText);

        win.display();
    }

    return 0;
}