1. 1. Game Development With SDL2
2. 2. Who Am I ? Eric Basile Engineer at Hitpoint Studios. Worked On Win8 & iOS titles Graduated From Champlain College in Burlington VT Game Programming BS SDL has been my side project for the last year. Website Portfolio : EricBasile.com Blog : FaceKeyboard.com Contact Email : eric@ericbasile.com Twitter : @Samurai336
3. 3. What Is SDL ? SDL stands for Simple Directmedia Layer Multimedia library that provides access to : Graphics, Sound, and Input devices. Cross Platform Set up to be a layer for interfacing with platform & operating-system-specific functions. Written in C Supported Platforms include : Windows, Linux, OSX, Android, iOS Open Source SDL2 uses zlib license
4. 4. History of SDL Created by Sam Lantinga at Loki Games 1998 Used to port Doom to BeOS SMPEG and OpenAL developed to work along side. SDL 1.3 Announced in 2008 (This would become 2.0) Would use zlib license 1.2 and older use GNU LGPL SDL 2.0 officially announced July 14 2012 Sam also announces he is joining valve software
5. 5. Whats new in 2 SDL v2.0.0 stable Released in August 11 2013 Not backwards compatible with SDL 1.2 Most repos only have 1.2 right now SDL2 Hardware accelerated 2D rendering using Direct3D, OpenGL or OpenGL ES or software rendering in background. Official Android and iOS support Support for multiple windows Much Much more. Over view at: http://wiki.libsdl.org/MigrationGuide
6. 6. Who's Using It ? And Tons of Indie developers !!
7. 7. Whats using it AND SO MUCH MORE !!
8. 8. Talk About Build Systems Cmake great for cross platform build systems Allows people to more or less use development environment of choice. Cross Platform (Duh!) Fairly straightforward scripting.
9. 9. Basic cmake syntax file(GLOB game_files src/*.c src/*.cpp src/*.h src/*.hpp) SOURCE_GROUP(Game FILES ${game_files}) add_executable(${App_Name} ${game_files} ) find_package(SDL2) include_directories( ${SDL2_INCLUDE_DIR} ${INCLUDE_DIRECTORIES} ) target_link_libraries(${App_Name} ${SDL2_LIBRARY}) Complete cmake available at : https://github.com/Samurai336/SDL2_PONG/blob/master/CMakeLists.txt set (App_Name "SDL2_PONG")
10. 10. Using Cmake Create Directory for your Project Build Avoid creating folder in Source Directory Run cmake Run cmake with path to directory containing CmakeLists.txt $ cmake Path/to/folder/With/Cmake/List/
11. 11. Cmake gui
12. 12. Basic SDL Application Initialize SDL Handle Events Draw Clean up Handle logic
13. 13. Initializing SDL SDL_Init(uint32 flags) ; We can pick and choose what parts of SDL we want to use (IE just Audio or just input). Available flags SDL_INIT_TIMER, SDL_INIT_AUDIO, SDL_INIT_VIDEO, SDL_INIT_JOYSTICK, SDL_INIT_HAPTIC, SDL_INIT_GAMECONTROLLER, SDL_INIT_EVENTS, SDL_INIT_EVERYTHING. Use or for multiple flags (SDL_INIT_TIMER|SDL_INIT_AUDIO) We will use SDL_INIT_EVERYTHING. Check things Started ok. if(SDL_Init(SDL_INIT_EVERYTHING) < 0) { printf("failed to initin"); }
14. 14. Create a window SDL_Window * MainWindow ; Pointer to what will be our main window SDL_Window* SDL_CreateWindow(const char* title, int x,int y,int w,int h,Uint32 flags) Will give us a pointer to a created window at with specified width, height, positon and title. Flags for windows include: SDL_WINDOW_FULLSCREEN, SDL_WINDOW_BORDERLESS, SDL_WINDOW_RESIZABLE and more. MainWindow = SDL_CreateWindow("SDL2_PONG", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 800, 600, SDL_WINDOW_RESIZABLE );
15. 15. Create Render Context SDL_Renderer* Renderer ; Pointer to our Renderer SDL_Renderer* SDL_CreateRenderer(SDL_Window* window, int index, Uint32 flags); Creates a 2D rendering context for a windows Pointer to the window the index of the rendering driver to initialize (-1 to initialize the first one supporting the requested flags) Enumerated flags to specify rendering context. Example : SDL_RENDERER_ACCELERATED for hardware accelerated SDL_CreateRenderer(MainWindow , -1, SDL_RENDERER_ACCELERATED );
16. 16. Extensions SDL Has Several Extensions Libraries Used to Abstract lower level but common SDL functionality (Ex : Loading Compressed Image formats) Extension Libraries Available: SDL_image, SDL_mixer,SDL_net, SDL_rtf, SDL_ttf. We will be Covering: SDL_image & SDL_mixer.
17. 17. Starting Extensions Initializing Extensions Image IMG_Init(int flags) What format libs to load for Decoding Ex : IMG_INIT_JPG for jpg We will be using png Mixer Mix_OpenAudio(int frequency, Uint16 format, int channels, int chunksize); We will use 44100 for frequency MIX_DEFAULT_FORMAT for our format 2 channels Chunk size of 4096 More or less whats Default in the Documentation :P Mix_OpenAudio(44100, MIX_DEFAULT_FORMAT, 2, 4096) IMG_Init(IMG_INIT_PNG);
18. 18. SDL Event Handling
19. 19. SDL_Event SDL_Event Handling Popular for abstracting input and other system messages across OS's and platforms Can Be used independently SDL_Init(SDL_INIT_EVENTS); Used for : SDL_KeyboardEvent SDL_MouseButtonEvent SDL_MouseMotionEvent SDL_WindowEvent SDL_TouchFingerEvent and more...
20. 20. Getting Events Use SDL_PollEvent(SDL_Event* event) to get currently pending event. Works nicely with while loops in the main loop. while (SDL_PollEvent(&event)) { // handle your event here }
21. 21. Check Event Type Get event type Event->type Will tell you what this event is. Ex: SDL_CommonEvent,SDL_QuitEvent, SDL_MouseButtonEvent, SDL_TouchEvent Works great in a Switch Statement switch(test_event->type) { case SDL_MOUSEMOTION: printf("We got a motion event.n"); printf("Current mouse position is: (%d, %d)n", test_event.motion.x, test_event.motion.y); break; default: printf("Unhandled Event!n"); break; } }
22. 22. Handling Event Use data from event Based on type Event->key.keysym.sym == SDLK_DOWN Handles down arrow. Keysym A structure that contains key information and sym is an SDL virtual key code. if(sym == SDLK_DOWN) { Player2.SetY(Player2.GetY() + 25); } else if(sym == SDLK_UP) { Player2.SetY(Player2.GetY() - 25); }
23. 23. 2D Drawing
24. 24. Cartesian plane in SDL +Y +X{0,0}
25. 25. Loading an Image as a texture SDL_texture* Is a structure that contains an efficient, driver-specific representation of pixel data. Using SDL_image SDL_Texture* IMG_LoadTexture(SDL_Renderer *renderer, const char *file) Pointer to the render context where we will display our image. Path to our file. 1.2 used SDL_Surface* OurTexture = IMG_LoadTexture(Renderer, "./ImageFile.png");
26. 26. Drawing Images With SDL_Renderer Will copy a portion of the texture to the current rendering target SDL_RenderCopyEx(Renderer, OurTexture, NULL, &DestR, 0.0, NULL, SDL_FLIP_NONE); DestR = {128,128,128,128}
27. 27. Sprite Sheet Animated Image Drawing Two SDL Rects SDL_Rects are just struct's with int's for X, Y Width and Height. One for where on the sprite sheet and one for where to display in the windows render context. Here's our source rect parameter would be {128,128,128,128} SDL_RenderCopyEx(Renderer, OurTexture, &SrcR, &DestR, 0.0, NULL, SDL_FLIP_NONE);
28. 28. Sprite Sheet Animated Image DrawingDestR = {128,128,128,128}
29. 29. Drawing to The Screen SDL_RenderPresent(SDL_Renderer* renderer) update the screen with rendering performed. SDL_RenderClear(SDL_Renderer* renderer) clear the current rendering target with the drawing color. These Need to be done every frame to see what we have drawn on screen. SDL_RenderPresent(Renderer); SDL_RenderClear(Renderer);
30. 30. Drawing Simple shapes SDL_SetRenderDrawColor(SDL_Renderer* renderer,Uint8 r,Uint8 g,Uint8 b,Uint8 a) Set our renderer's rgb draw color. SDL_RenderFillRect(SDL_Renderer* renderer,const SDL_Rect* rect) Draws a rect in the passed render context Also Available in SDL are : SDL_RenderDrawLine, SDL_RenderDrawLines, SDL_RenderDrawPoint, SDL_RenderDrawPoints, SDL_RenderDrawRect, SDL_RenderDrawRects. SDL_RenderFillRect(Renderer, &DestR);
31. 31. Sound
32. 32. Loading A sound File Using SDL_mixer Mix_Chunk* SoundFile; Pointer to Audio Data in memory Mix_Chunk *Mix_LoadWAV(const char *fname); Will load fname file into memory and return a pointer to it. Mix_Chunk* SoundFile = Mix_LoadWAV("./SoundFIle.wav") ;
33. 33. Playing Sounds Mix_PlayChannel (int channel, Mix_Chunk *chunk, int loops); Channel we want to play on -1 to let SDL choose it for you Pointer to our sound file How many times to loop 0 for once and -1 for infinite. Mix_PlayChannel(-1, SoundFile, 0);
34. 34. Clean up Its Important to Clean all the assets you have loaded into memory. Assets images SDL_DestroyTexture(OurTexture); Sounds Mix_FreeChunk(SoundFile) ;
35. 35. Shutting Down SDL Renderer SDL_DestroyRenderer(Renderer) ; Window SDL_DestroyWindow(MainWindow) ; Image Extension IMG_Quit(); Audio Mix_CloseAudio() ; SDL SDL_Quit() ;
36. 36. SDL2 Demo using Everything Discussed. Get It NOW !! $ git clone https://github.com/Samurai336/SDL2_PONG.git
37. 37. Reasons to use SDL beyond 2D games. Able to pick and choose parts of SDL to use Input handler, Audio handler.. etc Used for 3D games Great for creating OpenGL OpenGLes 1.0 & 2.0 and DirectX render contexts Now you have a way to handle cross platform input Works on just about anything Open source can compile it anywhere and add support yourself Works on Windows, Linux, Mac OS X, iOS, Android Sorta works on PSP and Raspberry Pi
38. 38. Resources Official website http://www.libsdl.org/ Documentation http://wiki.libsdl.org/ SDL 1.2 tutorials and information http://lazyfoo.net/SDL_tutorials/index.php http://www.sdltutorials.com/ History http://en.wikipedia.org/wiki/Simple_DirectMedia_Layer Game and company logos from http://store.steampowered.com/