Developing Programming Assignments on the XBOX 360 Console

Section II: The XnaAssignmentBase Library
b. Controlling a circle

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• Pre-requisite: it is assumed that you have read through this documentation (Section IIa. The library SDK).
• You can start with this begin template source (a completely empty project), and here is the end project source code we will generate at the end of this tutorial.
• Here is the keyboard mapping for the game controller.

Goals:

• To experience with drawing and interacting with users via the XnaAssignmentBase library.
• We will create this program where the program draws and allows the user to move a circle by manipulating the left thumbstick (or arrow keys).

Notice:  To work with the XnaAssignmentBase Library, a bare minimum project must include:

• Fonts: the Arial.spritefont must be part of the project
• 4 functions:
• Constructor: define the window drawing coordinate.
• InitializeWorld(): allocate memory and initialize instance variables.
• UpdateWorld(): poll user input and update application state. NOTE: no drawing in this function.
• DrawWorld(): draws the application state. NOTE: no update of any instance variable in this function.

• SourceCode folder contains an template SimpleXNA project.
• UsefulFiles folder contains:
• Arial.spritefont - this is the font we need in the project. We must create a proper folder and add this file into the project.
• XnaAssignmentBase_PC.dll and XnaAssignmentBase_XBOX.dll - these are the library files for Windows/PC projects and for XBOX 360 console projects respectively. We must include the reference to the appropriate file in our project.

1. Fix the compile error by specifying a proper coordinate system during construction.
2. Show how to include XnaAssignmentBase_PC.dll as a library reference for the project.
3. Include code to control and draw the circle.
4. Show how to include the font file in the Content folder.

public Game1() : base (new Vector2(0, 0), 15.0f) {}

• Create a folder for the library file:
• Go to explorer
• navigate to SimpleXNA
• Create a new folder: name it SupportFiles
• Copy UsefulFiles/XnaAssignmentBase_PC.dll into SupportFiles folder
• Include the library file as part of the project:
• Go back to GSE
• Right-Mouse-Button click over the project Reference folder:
• Add Reference
• Click on Browse tab
• navigate and select: SupportFiles/XnaAssignmentBase_PC.dll

• Instance variable: A circle is represented by its center:

Vector2 pos; // circle position



• InitializeWorld(): during initialization, we allocate memory and initialize the center position:

  protected override void  InitializeWorld() {             // Circle position             pos = new Vector2();             pos.X = 5.0f;                   pos.Y = 5.0f; }

  
  
• UpdateWorld(): update the center of the circle by the left thumbstick (or the arrow keys):

protected override void  UpdateWorld() {    if (XnaAssignmentBase.GamePad.ButtonBackClicked())         this.Exit();    Vector2 delta = XnaAssignmentBase.GamePad.ThumbSticks.Left;       pos += delta; }



• DrawWorld(): Draw the circle with a radius of 1.0f.

  protected override void DrawWorld() {      XnaAssignmentBase.DrawCircle(                   pos,         // Center                   1.0f,        // Radius                   0.0f,        // rotation                   Color.Red,   // Outside color                   Color.White, // Inside color                  "");         // Texture image to use          XnaAssignmentBase.EchoToBottomStatus("Circle Drawn at: " + pos); }

• Create the proper resource folder, in the GSE:
  • Right-Mouse-Button over the Content folder
    • Add -> New Folder:  name the new folder: Resources
  • Right-Mouse-Button over the newly created Resources folder
    • Add -> New Folder:  name the new folder: Fonts
  • Copy UsefulFiles/XnaAssignmentBase_PC.dll into SupportFiles folder
• Include the font file as part of the project:
• Right-Mouse-Button click over the newly created Fonts folder:
  • Add -> Existing Item ...
  • Navigate to UsefulFiles/Arial.spritefont