CSE 380 – Computer Game Programming GUIs for Games

1. CSE 380 – Computer Game ProgrammingGUIs for Games

2. ICON-28 • Science Fiction Convention • Founded by Stony Brook Students • http://www.iconsf.org/ • At Suffolk County Community College this year • April 3rd-5th • E-Gaming Track • they are looking for Stony Brook students to lend a hand • Interested? Contact Sandra Dumais • reeffish@verizon.net

3. Game GUI Controls • Stylistically fit in with game theme • drawn as artwork • careful font/color selection • Same rules should apply as with other GUIs • align components • uniform style • balance • clarity (single word options are best) • keep it simple • minimize depth • don’t make assumptions about your player’s IQ

4. What are Game GUIs for? • Starting/Stopping games • New Game, Save Game, Load Game, Pause, Continue, Quit • Game Options • level of difficulty • character selection & properties (RPG in particular) • chapter selection • Custom Controls Setup • In-game Decisions (strategy in particular) • Providing Help

5. Menu vs. In Game Controls • Menu controls, typically • simple, elegant • textual • centered on screen • allows for menu tabbling • tied to game controllers as well • In-game controls, typically • graphical • at bottom of screen • carefully grouped • tied to keystrokes for PC gaming (very important)

6. Halo’s Menu GUI

7. Starcraft’s In-game GUI

8. How might we make a GUI? • We’ll build our own buttons • Download, unzip, and examine the contents of: • EmptyGame.zip • my advice: set breakpoint on first line and debug a few frames • this means you’ll see every line execute

9. We know how do render images • Use images to render: • buttons • cursor • other GUI images • For buttons, use 2 images • mouse over • normal • each frame update the state based on mouse position

10. How do we test if the mouse is over a button? void Button::updateMouseOver(POINT *mousePoint) { // IS THE CURSOR OVER THIS BUTTON? if ((mousePoint->x >= x) && (mousePoint->x <= x + width) && (mousePoint->y >= y) && (mousePoint->y <= y + height) ) { mouseOver = true; } else { mouseOver = false; } }

11. Render Lists • Common approach in games • Each frame: • make a list of items to render • iterate through the list and render each item • throw out the list • RenderList is built and destroyed each frame • We’ll use 2 render lists: • one for the GUI • one for the game world

12. Render List Cheating • We’re not really going to use a list • Why? • we don’t want to allocate memory dynamically • Instead, we’ll use a giant array and pretend it’s a list • give the array a max size • don’t exceed that max size

13. A note about platform independence • Today our game’s graphics are drawn using DirectX • Tomorrow we may wish to use OpenGL • How can we minimize the difficulty of switching? • virtual functions • See: • GameGraphics & DirectXGameGraphics • TextureManager & DirectXTextureManager

14. To maximize platform independence • Confine technology-specific types and methods to technology-specific classes • Don’t let DirectX spill over into your data management classes

15. How do we respond to input? • Get Input • If game state is in main menu • Process input for main menu screen components • Draw main menu screen • Main Menu GUI • If game state is in game • Process input for game screen components • Draw game screen • Game GUI & Game World

16. Getting Input • We’ll use Windows methods • To test if a key is currently pressed: • GetAsyncKeyState(key) & 0X8000 • To get the current mouse position: • GetCursorPos(mousePoint); • To test if a mouse button is currently pressed: • GetAsyncKeyState(VK_LBUTTON) & 0X8000

17. Each Frame • We update data for: • all keys • first key press? • fill out struct for each key • mouse/cursor position • is mouse over buttons?

18. GameInput • Each frame: void GameInput::processInput(Game *game, WINDOWINFO wi) { updateCursorPosition(wi, game->getGUI()->getCursor()); updateInputState(); respondToKeyboardInput(game); respondToMouseInput(game); }

19. Custom Behavior • In the example I’ve given you, I have: • a core library • a custom example game • Customized behavior is loaded by key child classes: • DirectXGraphics • EGButtonEventHandler • EGKeyEventHandler • EGTextGenerator

20. Questions for you to figure out • Where is the programmed response to hitting SHIFT-C? • In what order are the GUI items rendered? • How can I speed up or slow down the frame rate? • How can you render something as more transparent? • How can we render changing text?