/* Simple program:  Move N sprites around on the screen as fast as possible */

 #include <stdlib.h>

 #include <stdio.h>

 #include <time.h>

 #include <math.h>

 #include "SDL.h"

 #define NUM_SPRITES	100

 #define MAX_SPEED 	1

 SDL_Surface *sprite;

 int numsprites;

 SDL_Rect *sprite_rects;

 SDL_Rect *positions;

 SDL_Rect *velocities;

 int sprites_visible;

 int debug_flip;

 Uint16 sprite_w, sprite_h;

 /* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */

 static void

 quit(int rc)

 {

     SDL_Quit();

     exit(rc);

 }

 int

 LoadSprite(char *file)

 {

     SDL_Surface *temp;

     /* Load the sprite image */

     sprite = SDL_LoadBMP(file);

     if (sprite == NULL) {

         fprintf(stderr, "Couldn't load %s: %s", file, SDL_GetError());

         return (-1);

     }

     /* Set transparent pixel as the pixel at (0,0) */

     if (sprite->format->palette) {

         SDL_SetColorKey(sprite, (SDL_SRCCOLORKEY | SDL_RLEACCEL),

                         *(Uint8 *) sprite->pixels);

     }

     /* Convert sprite to video format */

     temp = SDL_DisplayFormat(sprite);

     SDL_FreeSurface(sprite);

     if (temp == NULL) {

         fprintf(stderr, "Couldn't convert background: %s\n", SDL_GetError());

         return (-1);

     }

     sprite = temp;

     /* We're ready to roll. :) */

     return (0);

 }

 void

 MoveSprites(SDL_Surface * screen, Uint32 background)

 {

     int i, nupdates;

     SDL_Rect area, *position, *velocity;

     nupdates = 0;

     /* Erase all the sprites if necessary */

     if (sprites_visible) {

         SDL_FillRect(screen, NULL, background);

     }

     /* Move the sprite, bounce at the wall, and draw */

     for (i = 0; i < numsprites; ++i) {

         position = &positions[i];

         velocity = &velocities[i];

         position->x += velocity->x;

         if ((position->x < 0) || (position->x >= (screen->w - sprite_w))) {

             velocity->x = -velocity->x;

             position->x += velocity->x;

         }

         position->y += velocity->y;

         if ((position->y < 0) || (position->y >= (screen->h - sprite_w))) {

             velocity->y = -velocity->y;

             position->y += velocity->y;

         }

         /* Blit the sprite onto the screen */

         area = *position;

         SDL_BlitSurface(sprite, NULL, screen, &area);

         sprite_rects[nupdates++] = area;

     }

     if (debug_flip) {

         if ((screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF) {

             static int t = 0;

             Uint32 color = SDL_MapRGB(screen->format, 255, 0, 0);

             SDL_Rect r;

             r.x =

                 (sin((float) t * 2 * 3.1459) + 1.0) / 2.0 * (screen->w - 20);

             r.y = 0;

             r.w = 20;

             r.h = screen->h;

             SDL_FillRect(screen, &r, color);

             t += 2;

         }

     }

     /* Update the screen! */

     if ((screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF) {

         SDL_Flip(screen);

     } else {

         SDL_UpdateRects(screen, nupdates, sprite_rects);

     }

     sprites_visible = 1;

 }

 /* This is a way of telling whether or not to use hardware surfaces */

 Uint32

 FastestFlags(Uint32 flags, int width, int height, int bpp)

 {

     const SDL_VideoInfo *info;

     /* Hardware acceleration is only used in fullscreen mode */

     flags |= SDL_FULLSCREEN;

     /* Check for various video capabilities */

     info = SDL_GetVideoInfo();

     if (info->blit_hw_CC && info->blit_fill) {

         /* We use accelerated colorkeying and color filling */

         flags |= SDL_HWSURFACE;

     }

     /* If we have enough video memory, and will use accelerated

        blits directly to it, then use page flipping.

      */

     if ((flags & SDL_HWSURFACE) == SDL_HWSURFACE) {

         /* Direct hardware blitting without double-buffering

            causes really bad flickering.

          */

         if (info->video_mem * 1024 > (height * width * bpp / 8)) {

             flags |= SDL_DOUBLEBUF;

         } else {

             flags &= ~SDL_HWSURFACE;

         }

     }

     /* Return the flags */

     return (flags);

 }

 int

 main(int argc, char *argv[])

 {

     SDL_Surface *screen;

     Uint8 *mem;

     int width, height;

     Uint8 video_bpp;

     Uint32 videoflags;

     Uint32 background;

     int i, done;

     SDL_Event event;

     Uint32 then, now, frames;

     /* Initialize SDL */

     if (SDL_Init(SDL_INIT_VIDEO) < 0) {

         fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError());

         return (1);

     }

     numsprites = NUM_SPRITES;

     videoflags = SDL_SWSURFACE | SDL_ANYFORMAT;

     width = 640;

     height = 480;

     video_bpp = 8;

     debug_flip = 0;

     while (argc > 1) {

         --argc;

         if (strcmp(argv[argc - 1], "-width") == 0) {

             width = atoi(argv[argc]);

             --argc;

         } else if (strcmp(argv[argc - 1], "-height") == 0) {

             height = atoi(argv[argc]);

             --argc;

         } else if (strcmp(argv[argc - 1], "-bpp") == 0) {

             video_bpp = atoi(argv[argc]);

             videoflags &= ~SDL_ANYFORMAT;

             --argc;

         } else if (strcmp(argv[argc], "-fast") == 0) {

             videoflags = FastestFlags(videoflags, width, height, video_bpp);

         } else if (strcmp(argv[argc], "-hw") == 0) {

             videoflags ^= SDL_HWSURFACE;

         } else if (strcmp(argv[argc], "-flip") == 0) {

             videoflags ^= SDL_DOUBLEBUF;

         } else if (strcmp(argv[argc], "-debugflip") == 0) {

             debug_flip ^= 1;

         } else if (strcmp(argv[argc], "-fullscreen") == 0) {

             videoflags ^= SDL_FULLSCREEN;

         } else if (isdigit(argv[argc][0])) {

             numsprites = atoi(argv[argc]);

         } else {

             fprintf(stderr,

                     "Usage: %s [-bpp N] [-hw] [-flip] [-fast] [-fullscreen] [numsprites]\n",

                     argv[0]);

             quit(1);

         }

     }

     /* Set video mode */

     screen = SDL_SetVideoMode(width, height, video_bpp, videoflags);

     if (!screen) {

         fprintf(stderr, "Couldn't set %dx%d video mode: %s\n",

                 width, height, SDL_GetError());

         quit(2);

     }

     /* Load the sprite */

     if (LoadSprite("icon.bmp") < 0) {

         quit(1);

     }

     /* Allocate memory for the sprite info */

     mem = (Uint8 *) malloc(4 * sizeof(SDL_Rect) * numsprites);

     if (mem == NULL) {

         SDL_FreeSurface(sprite);

         fprintf(stderr, "Out of memory!\n");

         quit(2);

     }

     sprite_rects = (SDL_Rect *) mem;

     positions = sprite_rects;

     sprite_rects += numsprites;

     velocities = sprite_rects;

     sprite_rects += numsprites;

     sprite_w = sprite->w;

     sprite_h = sprite->h;

     srand(time(NULL));

     for (i = 0; i < numsprites; ++i) {

         positions[i].x = rand() % (screen->w - sprite_w);

         positions[i].y = rand() % (screen->h - sprite_h);

         positions[i].w = sprite->w;

         positions[i].h = sprite->h;

         velocities[i].x = 0;

         velocities[i].y = 0;

         while (!velocities[i].x && !velocities[i].y) {

             velocities[i].x = (rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED;

             velocities[i].y = (rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED;

         }

     }

     background = SDL_MapRGB(screen->format, 0x00, 0x00, 0x00);

     /* Print out information about our surfaces */

     printf("Screen is at %d bits per pixel\n", screen->format->BitsPerPixel);

     if ((screen->flags & SDL_HWSURFACE) == SDL_HWSURFACE) {

         printf("Screen is in video memory\n");

     } else {

         printf("Screen is in system memory\n");

     }

     if ((screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF) {

         printf("Screen has double-buffering enabled\n");

     }

     if ((sprite->flags & SDL_HWSURFACE) == SDL_HWSURFACE) {

         printf("Sprite is in video memory\n");

     } else {

         printf("Sprite is in system memory\n");

     }

     /* Run a sample blit to trigger blit acceleration */

     {

         SDL_Rect dst;

         dst.x = 0;

         dst.y = 0;

         dst.w = sprite->w;

         dst.h = sprite->h;

         SDL_BlitSurface(sprite, NULL, screen, &dst);

         SDL_FillRect(screen, &dst, background);

     }

     if ((sprite->flags & SDL_HWACCEL) == SDL_HWACCEL) {

         printf("Sprite blit uses hardware acceleration\n");

     }

     if ((sprite->flags & SDL_RLEACCEL) == SDL_RLEACCEL) {

         printf("Sprite blit uses RLE acceleration\n");

     }

     /* Loop, blitting sprites and waiting for a keystroke */

     frames = 0;

     then = SDL_GetTicks();

     done = 0;

     sprites_visible = 0;

     while (!done) {

         /* Check for events */

         ++frames;

         while (SDL_PollEvent(&event)) {

             switch (event.type) {

             case SDL_MOUSEBUTTONDOWN:

                 SDL_WarpMouse(screen->w / 2, screen->h / 2);

                 break;

             case SDL_KEYDOWN:

                 /* Any keypress quits the app... */

             case SDL_QUIT:

                 done = 1;

                 break;

             default:

                 break;

             }

         }

         MoveSprites(screen, background);

     }

     SDL_FreeSurface(sprite);

     free(mem);

     /* Print out some timing information */

     now = SDL_GetTicks();

     if (now > then) {

         printf("%2.2f frames per second\n",

                ((double) frames * 1000) / (now - then));

     }

     SDL_Quit();

     return (0);

 }