Lesson 16.3 – Functions to use weapons and potions

Lesson Objectives

At the end of this lesson, you will know…

• Nothing new. We’re just finishing the program, using the same things you learned in the previous lessons.

Now we’ll write the functions the player will use when fighting monsters.

We have two things they can do (besides click on one of the direction buttons, to run away from the battle): use a weapon on the monster or use a healing potion on themselves – if they have one in their inventory.

Here is the pseudo-code for the two functions:

Use a weapon function

• Get the currently selected weapon from the cboWeapons ComboBox
• Determine the amount of damage the player does to the monster
• Apply the damage to the monster’s CurrentHitPoints
  • Display message
• If the monster is dead (zero hit points remaining)
  • Display a victory message
  • Give player experience points for killing the monster
    • Display message
  • Give player gold for killing the monster
    • Display message
  • Get loot items from the monster
    • Display message for each loot item
    • Add item to player’s inventory
  • Refresh player data on UI
    • Gold and ExperiencePoints
    • Inventory list and ComboBoxes
  • “Move” player to current location
    • This will heal the player and create a new monster
• If the monster is still alive
  • Determine the amount of damage the monster does to the player
  • Display message
  • Subtract damage from player’s CurrentHitPoints
    • Refresh player data in UI
  • If player is dead (zero hit points remaining)
    • Display message
    • Move player to “Home” location

Use a potion function

• Get currently selected potion from cboPotions ComboBox
• Add healing amount to player’s CurrentHitPoints
  • CurrentHitPoints cannot exceed player’s MaximumHitPoints
• Remove the potion from the player’s inventory
• Display message
• Monster gets their turn to attack
  • Determine the amount of damage the monster does to the player
  • Display message
  • Subtract damage from player’s CurrentHitPoints
    • Refresh player data in UI
  • If player is dead (zero hit points remaining)
    • Display message
    • Move player to “Home” location
• Refresh player data in UI

These are much simpler functions than the MoveTo() function.

We’ll be able to use some of the smaller functions we created during the refactoring lesson – for example, the AddItemToInventory() function, from the Player class, if the player defeats the monster and receives loot items.

Adding functions for monster battles

Step 1: Start Visual Studio Express 2013 for Desktop, and open the solution.

Step 2: Right-click on the SuperAdventure.cs form in the SuperAdventure project, to start working with the code for the UI.

To add the ability to use weapons and potions in combat, you can add in the code below, or replace the code for SuperAdventure.cs with the code here: https://gist.github.com/ScottLilly/b20787650f2ab2a78362

For the btnUseWeapon_Click function, add this:

        private void btnUseWeapon_Click(object sender, EventArgs e)
        {
            // Get the currently selected weapon from the cboWeapons ComboBox
            Weapon currentWeapon = (Weapon)cboWeapons.SelectedItem;
            // Determine the amount of damage to do to the monster
            int damageToMonster = RandomNumberGenerator.NumberBetween(currentWeapon.MinimumDamage, currentWeapon.MaximumDamage);
            // Apply the damage to the monster's CurrentHitPoints
            _currentMonster.CurrentHitPoints -= damageToMonster;
            // Display message
            rtbMessages.Text += "You hit the " + _currentMonster.Name + " for " + damageToMonster.ToString() + " points." + Environment.NewLine;
            // Check if the monster is dead
            if(_currentMonster.CurrentHitPoints <= 0)
            {
                // Monster is dead
                rtbMessages.Text += Environment.NewLine;
                rtbMessages.Text += "You defeated the " + _currentMonster.Name + Environment.NewLine;
                // Give player experience points for killing the monster
                _player.ExperiencePoints += _currentMonster.RewardExperiencePoints;
                rtbMessages.Text += "You receive " + _currentMonster.RewardExperiencePoints.ToString() + " experience points" + Environment.NewLine;
                // Give player gold for killing the monster 
                _player.Gold += _currentMonster.RewardGold;
                rtbMessages.Text += "You receive " + _currentMonster.RewardGold.ToString() + " gold" + Environment.NewLine;
                // Get random loot items from the monster
                List<InventoryItem> lootedItems = new List<InventoryItem>();
                // Add items to the lootedItems list, comparing a random number to the drop percentage
                foreach(LootItem lootItem in _currentMonster.LootTable)
                {
                    if(RandomNumberGenerator.NumberBetween(1, 100) <= lootItem.DropPercentage)
                    {
                        lootedItems.Add(new InventoryItem(lootItem.Details, 1));
                    }
                }
                // If no items were randomly selected, then add the default loot item(s).
                if(lootedItems.Count == 0)
                {
                    foreach(LootItem lootItem in _currentMonster.LootTable)
                    {
                        if(lootItem.IsDefaultItem)
                        {
                            lootedItems.Add(new InventoryItem(lootItem.Details, 1));
                        }
                    }
                }
                // Add the looted items to the player's inventory
                foreach(InventoryItem inventoryItem in lootedItems)
                {
                    _player.AddItemToInventory(inventoryItem.Details);
                    if(inventoryItem.Quantity == 1)
                    {
                        rtbMessages.Text += "You loot " + inventoryItem.Quantity.ToString() + " " + inventoryItem.Details.Name +Environment.NewLine;
                    }
                    else
                    {
                        rtbMessages.Text += "You loot " + inventoryItem.Quantity.ToString() + " " + inventoryItem.Details.NamePlural + Environment.NewLine;
                    }
                }
                // Refresh player information and inventory controls
                lblHitPoints.Text = _player.CurrentHitPoints.ToString();
                lblGold.Text = _player.Gold.ToString();
                lblExperience.Text = _player.ExperiencePoints.ToString();
                lblLevel.Text = _player.Level.ToString();
                UpdateInventoryListInUI();
                UpdateWeaponListInUI();
                UpdatePotionListInUI();
                // Add a blank line to the messages box, just for appearance.
                rtbMessages.Text += Environment.NewLine;
                // Move player to current location (to heal player and create a new monster to fight)
                MoveTo(_player.CurrentLocation);
            }
            else
            {
                // Monster is still alive
                // Determine the amount of damage the monster does to the player
                int damageToPlayer = RandomNumberGenerator.NumberBetween(0, _currentMonster.MaximumDamage);
                // Display message
                rtbMessages.Text += "The " + _currentMonster.Name + " did " + damageToPlayer.ToString() + " points of damage." + Environment.NewLine;
                // Subtract damage from player
                _player.CurrentHitPoints -= damageToPlayer;
                // Refresh player data in UI
                lblHitPoints.Text = _player.CurrentHitPoints.ToString();
                if(_player.CurrentHitPoints <= 0)
                {
                    // Display message
                    rtbMessages.Text += "The " + _currentMonster.Name + " killed you." + Environment.NewLine;
                    // Move player to "Home"
                    MoveTo(World.LocationByID(World.LOCATION_ID_HOME));
                }
            }
        }

Then, for the btnUsePotion_Click function, add this:

        private void btnUsePotion_Click(object sender, EventArgs e)
        {
            // Get the currently selected potion from the combobox
            HealingPotion potion = (HealingPotion)cboPotions.SelectedItem;
            // Add healing amount to the player's current hit points
            _player.CurrentHitPoints = (_player.CurrentHitPoints + potion.AmountToHeal);
            // CurrentHitPoints cannot exceed player's MaximumHitPoints
            if(_player.CurrentHitPoints > _player.MaximumHitPoints)
            {
                _player.CurrentHitPoints = _player.MaximumHitPoints;
            }
            // Remove the potion from the player's inventory
            foreach(InventoryItem ii in _player.Inventory)
            {
                if(ii.Details.ID == potion.ID)
                {
                    ii.Quantity--;
                    break;
                }
            }
            // Display message
            rtbMessages.Text += "You drink a " + potion.Name + Environment.NewLine;
            // Monster gets their turn to attack
            // Determine the amount of damage the monster does to the player
            int damageToPlayer = RandomNumberGenerator.NumberBetween(0, _currentMonster.MaximumDamage);
            // Display message
            rtbMessages.Text += "The " + _currentMonster.Name + " did " + damageToPlayer.ToString() + " points of damage." + Environment.NewLine;
            // Subtract damage from player
            _player.CurrentHitPoints -= damageToPlayer;
            if(_player.CurrentHitPoints <= 0)
            {
                // Display message
                rtbMessages.Text += "The " + _currentMonster.Name + " killed you." + Environment.NewLine;
                // Move player to "Home"
                MoveTo(World.LocationByID(World.LOCATION_ID_HOME));
            }
            // Refresh player data in UI
            lblHitPoints.Text = _player.CurrentHitPoints.ToString();
            UpdateInventoryListInUI();
            UpdatePotionListInUI();
        }

There isn’t really anything new in these two functions. Just more “if”s and “foreach”s to handle the player’s actions in battle.

Summary

Now you have a working game. The player can move around in the world, get quests, battle monsters, receive loot, and complete quests.

These new functions could use some refactoring, since they are long and do several things. I’ll leave that to you to figure out what refactoring you’d do.

Source code for this lesson

Source code on GitHub

Source code on Dropbox

 Next lesson: Lesson 17.1 – Running the game on another computer

Previous lesson: Lesson 16.2 – Refactoring the player movement function

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