kc3-lang/SDL/Xcode-iOS/Demos/src/happy.c

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• Hash : b88ca1b4
  Author :
  Date : 2015-02-10T16:28:56
  

  the last parameter of XChangeProperty is the number of elements.. and when the element format is 32.. the element is "long" so we have 5 long elements here. Yes this seems confusing as on mac+linux Long is either 32 or 64bits depending on the architecture, but this is how the X11 protocol is defined. Thus 5 is the correct value for the nelts here. Not 5 or 10 depending on the architecture. More info on the confusion https://bugs.freedesktop.org/show_bug.cgi?id=16802

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• Xcode-iOS/Demos/src/happy.c

• /*
   *  happy.c
   *  written by Holmes Futrell
   *  use however you want
   */
  
  #include "SDL.h"
  #include "common.h"
  
  #define NUM_HAPPY_FACES 100     /* number of faces to draw */
  #define MILLESECONDS_PER_FRAME 16       /* about 60 frames per second */
  #define HAPPY_FACE_SIZE 32      /* width and height of happyface (pixels) */
  
  static SDL_Texture *texture = 0;    /* reference to texture holding happyface */
  
  static struct
  {
      float x, y;                 /* position of happyface */
      float xvel, yvel;           /* velocity of happyface */
  } faces[NUM_HAPPY_FACES];
  
  /*
      Sets initial positions and velocities of happyfaces
      units of velocity are pixels per millesecond
  */
  void
  initializeHappyFaces()
  {
      int i;
      for (i = 0; i < NUM_HAPPY_FACES; i++) {
          faces[i].x = randomFloat(0.0f, SCREEN_WIDTH - HAPPY_FACE_SIZE);
          faces[i].y = randomFloat(0.0f, SCREEN_HEIGHT - HAPPY_FACE_SIZE);
          faces[i].xvel = randomFloat(-0.1f, 0.1f);
          faces[i].yvel = randomFloat(-0.1f, 0.1f);
      }
  }
  
  void
  render(SDL_Renderer *renderer)
  {
  
      int i;
      SDL_Rect srcRect;
      SDL_Rect dstRect;
  
      /* setup boundaries for happyface bouncing */
      Uint16 maxx = SCREEN_WIDTH - HAPPY_FACE_SIZE;
      Uint16 maxy = SCREEN_HEIGHT - HAPPY_FACE_SIZE;
      Uint16 minx = 0;
      Uint16 miny = 0;
  
      /* setup rects for drawing */
      srcRect.x = 0;
      srcRect.y = 0;
      srcRect.w = HAPPY_FACE_SIZE;
      srcRect.h = HAPPY_FACE_SIZE;
      dstRect.w = HAPPY_FACE_SIZE;
      dstRect.h = HAPPY_FACE_SIZE;
  
      /* fill background in with black */
      SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
      SDL_RenderClear(renderer);
  
      /*
         loop through all the happy faces:
         - update position
         - update velocity (if boundary is hit)
         - draw
       */
      for (i = 0; i < NUM_HAPPY_FACES; i++) {
          faces[i].x += faces[i].xvel * MILLESECONDS_PER_FRAME;
          faces[i].y += faces[i].yvel * MILLESECONDS_PER_FRAME;
          if (faces[i].x > maxx) {
              faces[i].x = maxx;
              faces[i].xvel = -faces[i].xvel;
          } else if (faces[i].y > maxy) {
              faces[i].y = maxy;
              faces[i].yvel = -faces[i].yvel;
          }
          if (faces[i].x < minx) {
              faces[i].x = minx;
              faces[i].xvel = -faces[i].xvel;
          } else if (faces[i].y < miny) {
              faces[i].y = miny;
              faces[i].yvel = -faces[i].yvel;
          }
          dstRect.x = faces[i].x;
          dstRect.y = faces[i].y;
          SDL_RenderCopy(renderer, texture, &srcRect, &dstRect);
      }
      /* update screen */
      SDL_RenderPresent(renderer);
  
  }
  
  /*
      loads the happyface graphic into a texture
  */
  void
  initializeTexture(SDL_Renderer *renderer)
  {
      SDL_Surface *bmp_surface;
      /* load the bmp */
      bmp_surface = SDL_LoadBMP("icon.bmp");
      if (bmp_surface == NULL) {
          fatalError("could not load bmp");
      }
      /* set white to transparent on the happyface */
      SDL_SetColorKey(bmp_surface, 1,
                      SDL_MapRGB(bmp_surface->format, 255, 255, 255));
  
      /* convert RGBA surface to texture */
      texture = SDL_CreateTextureFromSurface(renderer, bmp_surface);
      if (texture == 0) {
          fatalError("could not create texture");
      }
      SDL_SetTextureBlendMode(texture, SDL_BLENDMODE_BLEND);
  
      /* free up allocated memory */
      SDL_FreeSurface(bmp_surface);
  }
  
  int
  main(int argc, char *argv[])
  {
  
      SDL_Window *window;
      SDL_Renderer *renderer;
      Uint32 startFrame;
      Uint32 endFrame;
      Uint32 delay;
      int done;
  
      /* initialize SDL */
      if (SDL_Init(SDL_INIT_VIDEO) < 0) {
          fatalError("Could not initialize SDL");
      }
      window = SDL_CreateWindow(NULL, 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT,
                                  SDL_WINDOW_OPENGL |
                                  SDL_WINDOW_BORDERLESS);
  
      renderer = SDL_CreateRenderer(window, -1, 0);
  
      initializeTexture(renderer);
      initializeHappyFaces();
  
      /* main loop */
      done = 0;
      while (!done) {
          startFrame = SDL_GetTicks();
          SDL_Event event;
          while (SDL_PollEvent(&event)) {
              if (event.type == SDL_QUIT) {
                  done = 1;
              }
          }
          render(renderer);
          endFrame = SDL_GetTicks();
  
          /* figure out how much time we have left, and then sleep */
          delay = MILLESECONDS_PER_FRAME - (endFrame - startFrame);
          if (delay < 0) {
              delay = 0;
          } else if (delay > MILLESECONDS_PER_FRAME) {
              delay = MILLESECONDS_PER_FRAME;
          }
          SDL_Delay(delay);
      }
  
      /* cleanup */
      SDL_DestroyTexture(texture);
      /* shutdown SDL */
      SDL_Quit();
  
      return 0;
  
  }
  

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