josh-co.com

Now that I have a basic house interior working, the next step is to add a shop to my game. This is something else that turned out to be much easier than I expected. I was able to handle this using additional game states/screens.

First thing, if you didn’t take a look at the game state management link that I posted, go check it out. It’s great and simple. To handle my menu selection, I studied some code around the internet (such as the platformer tutorial) and modified it. First create a new class named menuItem.cs

// 4-10-2012 Converted to automatic properties

using System;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Content;

namespace FarmGame.ScreenManagement
{
    class MenuItem
    {
        public string Text { get; set; }

        public Vector2 Position { get; set; }

        public bool IsSelected { get; set; }

        public ContentManager Content { get; set; }

        public Texture2D Texture { get; set; }

        private bool Textured = false;

        public MenuItem(string text, ContentManager content)
        {
            this.Text = text;
            this.Content = content;
        }

        public MenuItem(string text, ContentManager content, Vector2 position)
        {
            this.Text = text;
            this.Content = content;
            this.Position = position;
        }

        public MenuItem(string text, ContentManager content, Vector2 position, string texture)
        {
            this.Text = text;
            this.Content = content;
            this.Position = position;
            this.Texture = content.Load<Texture2D>(texture);
            Textured = true;
        }

        public void Update(GameTime gameTime)
        {

        }

        public void Draw(SpriteBatch sb)
        {
            if (!Textured)
            {
                SpriteFont font = Content.Load<SpriteFont>(@"Fonts\SpriteFont1");
                Color color = IsSelected ? Color.Yellow : Color.White;
                float scale = IsSelected ? 1.5f : 1.0f;
                Vector2 origin = new Vector2(0, font.LineSpacing / 2);

                sb.DrawString(font, Text, Position, color, 0, origin, scale, SpriteEffects.None, 0);
            }
            else
            {
                Color color = IsSelected ? Color.Yellow : Color.White;

                sb.Draw(Texture, Position, color);
            }
        }
    }
}

This is basically just a text object, though I modified the class so that it can be a textured menu item as well, that is what the overloaded constructor is for.
The draw method basically checks to see if it is a textured sprite and will either draw the texture, or the text.

Before we add in our new game screen, here is my code for my screen class. I have made a few changes from what was done in the tutorial that I followed:

// 4-10-2012 Converted properties to automatic properties

using System;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using FarmGame.Inventory;

namespace FarmGame.ScreenManagement
{
    class Screen
    {
        public GraphicsDevice GraphicsDevice { get; set; }

        public String Name { get; set; }
        public Player Player { get; set; }
        public PlayerInventory Inventory { get; set; }

        //public Game Game { get; set; }

        //constructor
        public Screen(GraphicsDevice gd, string name)
        {
            this.Name = name;
            this.GraphicsDevice = gd;
            //this.Game = game;
        }

        public virtual bool Init()
        {
            return true;
        }

        public virtual void Shutdown()
        {
            
        }

        public virtual void Update(GameTime gameTime)
        {
        }

        public virtual void Draw(GameTime gameTime, SpriteBatch sb)
        {
        }
    }
}

The biggest difference from the tutorial is that I am passing in and storing my inventory and player objects here. This way, it is easier to pass them around when going inside my houes, into a shop, into the overworld, etc. Everything else is pretty basic.

Now, we need to add a new gamescreen named Shop

using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Content;
using FarmGame.ScreenManagement;
using FarmGame.TileEngine;
//using FarmGame.Tile_Engine2;
using FarmGame.Inventory;
using Microsoft.Xna.Framework.Input;

namespace FarmGame
{
    class ShopScreen : Screen
    {
        public ContentManager Content { get; set; }

        public ScreenManager Screens { get; set; }

        GraphicsDeviceManager Graphics { get; set; }

        GraphicsDevice Device { get; set; }

        private List<MenuItem> Menu = new List<MenuItem>();

        //text handler object to handle all of our text drawing
        public Text TextHandler { get; set; }

        KeyboardState keyState;
        KeyboardState prevState;

        int selectedEntry = 0;

        public ShopScreen(GraphicsDevice device, ContentManager content, ScreenManager screenManager, GraphicsDeviceManager graphics)
            : base(device, "ShopScreen")
        {
            this.Content = content;
            this.Screens = screenManager;
            this.Graphics = graphics;
            this.Device = device;

            //this.menu.Add(new MenuItem(menuTitle, content, new Vector2(200, 200)));
            this.Menu.Add(new MenuItem("Buy", Content, new Vector2(200, 240), @"UI\buyBtn"));
            this.Menu.Add(new MenuItem("Sell", Content, new Vector2(200, 320), @"UI\sellBtn"));
            this.Menu.Add(new MenuItem("Exit", Content, new Vector2(200, 400), @"UI\exitBtn"));

            this.Menu[0].IsSelected = true;
        }

        public override bool Init()
        {
            TextHandler = new Text(this.Content, @"Fonts\SpriteFont1");
            TextHandler.TextColor = Color.Black;

            // keyState = Keyboard.GetState();

            return base.Init();
        }

        public override void Shutdown()
        {
            base.Shutdown();
        }

        public override void Draw(GameTime gameTime, SpriteBatch sb)
        {
            base.GraphicsDevice.Clear(Color.CornflowerBlue);

            sb.Begin();
            foreach (MenuItem mi in this.Menu)
                mi.Draw(sb);

            TextHandler.FontPos = new Vector2(120, 150);
            TextHandler.Output = "Welcome to the shop.";
            TextHandler.DrawText(sb);

            TextHandler.FontPos = new Vector2(TextHandler.FontPos.X, TextHandler.FontPos.Y + 30);
            TextHandler.Output = "What would you like to do?";
            TextHandler.DrawText(sb);

            sb.End();

            base.Draw(gameTime, sb);
        }

        public override void Update(GameTime gameTime)
        {
            prevState = keyState;
            keyState = Keyboard.GetState();

            //move our selection up or down
            if (keyState.IsKeyDown(Keys.Up) && !prevState.IsKeyDown(Keys.Up))
                selectedEntry--;
            else if (keyState.IsKeyDown(Keys.Down) && !prevState.IsKeyDown(Keys.Down))
                selectedEntry++;
            else if (keyState.IsKeyDown(Keys.Enter) && !prevState.IsKeyDown(Keys.Enter))
            {
                if (this.Menu[0].IsSelected)
                {
                    throw new NotImplementedException();
                }
                else if (this.Menu[1].IsSelected)
                {
                    Screens.GoToScreen("SellScreen", Inventory, Player);
                }
                else if (this.Menu[2].IsSelected)
                {
                    Screens.GoToScreen("GameScreen", Inventory, Player);
                }
            }

            //go to the beginning or end of the list
            if (selectedEntry < 0)
                selectedEntry = this.Menu.Count - 1;
            if (selectedEntry == this.Menu.Count )
                selectedEntry = 0;

            foreach (MenuItem mi in this.Menu)
            {
                if (mi == this.Menu[selectedEntry])
                    mi.IsSelected = true;
                else
                    mi.IsSelected = false;

                mi.Update(gameTime);
            }
            base.Update(gameTime);
        }
    }
}

Like usual, i’m not going to explain all the code as it should be pretty simple. What’s important is that we start out with a list of menu items. This is how we will display and select the menu items. Like many of my other tutorials, I am using a custom made text object to handle my non-menu text output.

            this.Menu.Add(new MenuItem("Buy", Content, new Vector2(200, 240), @"UI\buyBtn"));
            this.Menu.Add(new MenuItem("Sell", Content, new Vector2(200, 320), @"UI\sellBtn"));
            this.Menu.Add(new MenuItem("Exit", Content, new Vector2(200, 400), @"UI\exitBtn"));

            this.Menu[0].IsSelected = true;

This code is how we add new menu items and the last line is flagging the first item as selected. If you go back to the first section of code for our menu item class, you can see that if the isSelected boolean is true, the tint of the texture or the color of the font will be different. The update code is pretty basic too. Currently, the buy portion of my shop is not implemented so it throws an appropriate error. Selling takes you to a different screen and exiting takes you back to the game screen. The code does check the selected index and makes sure it is within the bounds of our list. If it goes past, we set it back to 0, if we go below, we set it to the end. That way there is always a menu item selected.

That’s it. You can now have a pretty basic shop. I’m still working on tweaking the code for my “sell shop.” Once this is done I’ll try to get the code posted.

One thing that was important to me in my latest game was to have actual dialog show on the screen. When the player interacts with objects, I want a box to display on the screen to give them immediate feedback. Granted, my implementation makes some basic assumptions and is quite simple, it is working and scaling quite well for me. Here is a basic implementation:

using System;
using FarmGame.Inventory;
using FarmGame.TileEngine;

namespace FarmGame.Dialogue
{
    static class GameObjectDialogue
    {

        static public string GetOutput(InventoryItem item, GameObject go, out bool harvestable)
        {
            harvestable = false;

            if (go.thisType == GameObject.ObjectType.rock)
                return GetRockOutput(item, out harvestable);
            if (go.thisType == GameObject.ObjectType.bush)
                return GetBushOutput(item, out harvestable);
            if (go.thisType == GameObject.ObjectType.tree)
                return GetTreeOutput(item, out harvestable);
            if (go.thisType == GameObject.ObjectType.house)
                return GetHouseOutput(out harvestable);
            
            return string.Empty;
        }

        private static string GetHouseOutput(out bool harvestable)
        {
            harvestable = false;
            return "This is your house.";    
        }

        private static string GetTreeOutput(InventoryItem ii, out bool harvestable)
        {
            if (ii.ItemName == "axe")
            {
                harvestable = true;
                return "Press space to chop this tree.";
            }
            else
            {
                harvestable = false;
                return "You must have the axe equipped.";
            }
        }

        static public string GetRockOutput(InventoryItem ii, out bool harvestable)
        {
            if (ii.ItemName == "pickaxe")
            {
                harvestable = true;
                return "Press space to mine this rock.";
            }
            else
            {
                harvestable = false;
                return "You must have the pickaxe equipped.";
            }
        }

        static public string GetBushOutput(InventoryItem ii, out bool harvestable)
        {
            if (ii.ItemName == "scythe")
            {
                harvestable = true;
                return "Press space to harvest berries.";
            }
            else
            {
                harvestable = false;
                return "You must have the scythe equipped.";
            }
        }
    }
}

I won’t get too into the details as it should be self explanatory. In this case, you are passing in the equipped item and the object you are interacting with. It will then return if the object is harvestable. In my case, I have rocks, bushes, trees, and a house.

Calling it from your code is equally as simple. I have this in the update method of my level class:

            bool dialogBoxNeeded = false;

if (tileRect.Intersects(Player.fowardBox()))
                {
                    bool harvestable;

                    box.Position = new Vector2(tileRect.X + 5, tileRect.Y + 5);

                    //box.textHandler.Output = "Press space to mine this rock.";
                    box.textHandler.Output = GameObjectDialogue.GetOutput(Inventory.EquippedItem, go, out harvestable);
                    dialogBoxNeeded = true;

                    //check for action key
                    if (keyState.IsKeyDown(Keys.Space) && !prevKeyState.IsKeyDown(Keys.Space))
                    {
                        //add additional code here to return items 
                        if (harvestable)
                        {
                            Harvesting.Harvest(go, ref Inventory, ref GameObjects, CM);
                            //this.GameObjects.Remove(go);
                            return;
                        }
                    }
                }

                box.DrawBox = dialogBoxNeeded;

Basically, the player has a seperate bounding box that projects in front of them. We are checking this bounding box to see if it interacts with a game object. If so, we note the position for our box, determine the text, and flag the code as needing a dialog box.

Now we need to call the draw method:

            if (this.box.DrawBox)
                this.box.Draw(sb);

I’m not going to step through it, but here is the box class:

using System;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System.Text;
using Microsoft.Xna.Framework.Content;

namespace FarmGame.UI_Elements
{
    class Box
    {
        public Text textHandler { get; set; }
        public Texture2D Texture { get; set; }
        public Vector2 Position { get; set; }
        public bool DrawBox { get; set; }

        //private int TextureWidth { get; set; }
        //private int TextureHeight { get; set; }

        private string Output;
        //StringBuilder sb;

        public Box(ContentManager cm)
        {
            this.Texture = cm.Load<Texture2D>(@"UI\popuptext");

            textHandler = new Text(cm, @"Fonts\boxSpriteFont");
            textHandler.TextColor = Color.White;
        }

        public Box(ContentManager cm, string output, Vector2 coords)
        {
            this.Texture = cm.Load<Texture2D>(@"UI\popuptext");
            this.Output = output;
            this.Position = coords;

            textHandler = new Text(cm, @"Fonts\boxSpriteFont");
            textHandler.TextColor = Color.White;
        }

        public void Draw(SpriteBatch sb)
        {
            sb.Draw(this.Texture, this.Position, null, Color.White );

            textHandler.FontPos = new Vector2(Position.X + 15, Position.Y + 15);
            textHandler.DrawText(sb);
        }
    }
}