Intro to Game Development An introduction to Swing, Java2D, JOGL, and game design Created by: Dennis Lawter and Dustin Scott

Game Theory  Logic  AI, Game Objects  Timer  The Game Loop  Controller  Java AWT listeners  Visuals & Audio  Java2D vs. OpenGL, Java Sound vs. OpenAL

Logic  GameObject – Inheritence!  Player  Affected by the controller  Enemy  Affected by AI  Ground  Serves as an obstacle or boundary  Projectile  Bullets for doing damage  NPC (Non Playable Character)  Allows greater interactivity  AI, dialogs, quests, and plot progression

Timer  The Game Loop  Slowdown  The game and graphics are affected equally by the timer.  Frame-skip  The graphics update as fast as possible, while the objects update on a timer.  Updating objects  The game loop calls each object’s update() method.  We assume this is called 60 times per second. We can start a count off this timer to pause events (slowing animation or shooting rate).  Each object can reassess its situation and act accordingly.  Simple objects may do nothing, such as a ground block.

Timer  Physics  Collision  A collision layer must be made. It can be either a bounding box, a number of smaller geographic shapes, or a pixel-by-pixel mask. A mask is a matrix of Boolean values to determine the solid pixels the object occupies.  We will define collision as two objects moving into a state wherein they share at least one pixel in their collision layer.  Intersection  If we have boxes, we can compare their x, y, width, and height to determine if they are colliding.  If we have a mask, we can shift one mask to match its position in the graphics and apply the bitwise AND function to the matrix.  Snapping  When stopping an object’s motion against a wall, we must move them into contact with the wall, rather than simply disallowing them to move.

Controller  There are a number of ways to interpret a button press  Pressed down event  Activated only at the instant the button is pressed  Held down repeating event  A Boolean holds this value so that we may check it during update.  Released event  Activated only on the release of a button. This is useful for quick press events. Compare this to the actions of clicking a link.  Typing event  Should we implement our own display for text, such as a chat window, we would have to check for focus on the chat window and add text if necessary.

Graphics  Java2D  We draw everything within a JPanel (Swing component).  We override the paint method, with a Graphics parameter.  The Graphics2D class (casted from Graphics) allows us to draw a number of shapes and objects.  We may draw lines, Strings, and Images.  JOGL  Similar to the previous methodology. A GLCanvas is made in place of a JPanel.  A GLEventListener is overridden to handle the drawing.  GLAutoDrawable is used rather than Graphics.

OpenGL vs. DirectX vs. Java2D  OpenGL – Stands for Open Graphics Library. It is an API primarily designed as an abstraction for graphical processing. It is primarily used cross-platform 3D graphics.  DirectX – Microsoft’s API for abstraction for hardware access. It includes almost all Utilities necessary for game development.  Java2D – Java’s prepackaged graphics library. Using the CPU for graphic processing, it does not standup to the other APIs due to the inability to utilize specialized hardware.

OpenGL

DirectX

Java2D  Useful for simple, quick or low graphics intensity applications.  Cross-platform  Built-in to java  Quickly overwhelmed in graphics intensive applications due to its shared CPU usage.

Setting up JOGL in Eclipse  JOGL will require system libraries to execute properly.  Eclipse must be setup to use JOGL, and must be reconfigured if the drive letter changes, unless the configurations are hard-coded.