FUNCTIONS

1. LoadSprite
2. MoveSprites
3. FastestFlags
4. main

   2 /* Simple program:  Move N sprites around on the screen as fast as possible */
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <string.h>
   7 #include <ctype.h>
   8 #include <time.h>
  10 #include "SDL.h"
  12 #define NUM_SPRITES     100
  13 #define MAX_SPEED       1
  15 SDL_Surface *sprite;
  16 int numsprites;
  17 SDL_Rect *sprite_rects;
  18 SDL_Rect *positions;
  19 SDL_Rect *velocities;
  20 int sprites_visible;
  22 int LoadSprite(SDL_Surface *screen, char *file)
     /* [<][>][^][v][top][bottom][index][help] */
  23 {
  24         SDL_Surface *temp;
  26         /* Load the sprite image */
  27         sprite = SDL_LoadBMP(file);
  28         if ( sprite == NULL ) {
  29                 fprintf(stderr, "Couldn't load %s: %s", file, SDL_GetError());
  30                 return(-1);
  31         }
  33         /* Set transparent pixel as the pixel at (0,0) */
  34         if ( sprite->format->palette ) {
SDL_SetColorKey(sprite, (SDL_SRCCOLORKEY|SDL_RLEACCEL),
  36                                                 *(Uint8 *)sprite->pixels);
  37         }
  39         /* Convert sprite to video format */
  40         temp = SDL_DisplayFormat(sprite);
SDL_FreeSurface(sprite);
  42         if ( temp == NULL ) {
  43                 fprintf(stderr, "Couldn't convert background: %s\n",
SDL_GetError());
  45                 return(-1);
  46         }
  47         sprite = temp;
  49         /* We're ready to roll. :) */
  50         return(0);
  51 }
  53 void MoveSprites(SDL_Surface *screen, Uint32 background)
     /* [<][>][^][v][top][bottom][index][help] */
  54 {
  55         int i, nupdates;
  56         SDL_Rect area, *position, *velocity;
  58         nupdates = 0;
  59         /* Erase all the sprites if necessary */
  60         if ( sprites_visible ) {
SDL_FillRect(screen, NULL, background);
  62         }
  64         /* Move the sprite, bounce at the wall, and draw */
  65         for ( i=0; i<numsprites; ++i ) {
  66                 position = &positions[i];
  67                 velocity = &velocities[i];
  68                 position->x += velocity->x;
  69                 if ( (position->x < 0) || (position->x >= screen->w) ) {
  70                         velocity->x = -velocity->x;
  71                         position->x += velocity->x;
  72                 }
  73                 position->y += velocity->y;
  74                 if ( (position->y < 0) || (position->y >= screen->h) ) {
  75                         velocity->y = -velocity->y;
  76                         position->y += velocity->y;
  77                 }
  79                 /* Blit the sprite onto the screen */
  80                 area = *position;
  81                 SDL_BlitSurface(sprite, NULL, screen, &area);
  82                 sprite_rects[nupdates++] = area;
  83         }
  85         /* Update the screen! */
  86         if ( (screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF ) {
SDL_Flip(screen);
  88         } else {
SDL_UpdateRects(screen, nupdates, sprite_rects);
  90         }
  91         sprites_visible = 1;
  92 }
  94 /* This is a way of telling whether or not to use hardware surfaces */
  95 Uint32 FastestFlags(Uint32 flags)
     /* [<][>][^][v][top][bottom][index][help] */
  96 {
  97         const SDL_VideoInfo *info;
  99         /* Hardware acceleration is only used in fullscreen mode */
 100         flags |= SDL_FULLSCREEN;
 102         /* Check for various video capabilities */
 103         info = SDL_GetVideoInfo();
 104         if ( info->blit_hw_CC && info->blit_fill ) {
 105                 /* We use accelerated colorkeying and color filling */
 106                 flags |= SDL_HWSURFACE;
 107         }
 108         /* If we have enough video memory, and will use accelerated
 109            blits directly to it, then use page flipping.
 110          */
 111         if ( (flags & SDL_HWSURFACE) == SDL_HWSURFACE ) {
 112                 /* Direct hardware blitting without double-buffering
 113                    causes really bad flickering.
 114                  */
 115                 SDL_Surface *screen = SDL_GetVideoSurface();
 116                 if ( info->video_mem > (screen->h*screen->pitch) ) {
 117                         flags |= SDL_DOUBLEBUF;
 118                 } else {
 119                         flags &= ~SDL_HWSURFACE;
 120                 }
 121         }
 123         /* Return the flags */
 124         return(flags);
 125 }
 127 int main(int argc, char *argv[])
     /* [<][>][^][v][top][bottom][index][help] */
 128 {
 129         SDL_Surface *screen;
 130         Uint8 *mem;
 131         int width, height;
 132         Uint8  video_bpp;
 133         Uint32 videoflags;
 134         Uint32 background;
 135         int    i, done;
 136         SDL_Event event;
 137         Uint32 then, now, frames;
 139         /* Initialize SDL */
 140         if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
 141                 fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
 142                 exit(1);
 143         }
 144         atexit(SDL_Quit);
 146         numsprites = NUM_SPRITES;
 147         videoflags = SDL_SWSURFACE|SDL_ANYFORMAT;
 148         width = 640;
 149         height = 480;
 150         video_bpp = 8;
 151         while ( argc > 1 ) {
 152                 --argc;
 153                 if ( strcmp(argv[argc-1], "-width") == 0 ) {
 154                         width = atoi(argv[argc]);
 155                         --argc;
 156                 } else
 157                 if ( strcmp(argv[argc-1], "-height") == 0 ) {
 158                         height = atoi(argv[argc]);
 159                         --argc;
 160                 } else
 161                 if ( strcmp(argv[argc-1], "-bpp") == 0 ) {
 162                         video_bpp = atoi(argv[argc]);
 163                         videoflags &= ~SDL_ANYFORMAT;
 164                         --argc;
 165                 } else
 166                 if ( strcmp(argv[argc], "-fast") == 0 ) {
 167                         videoflags = FastestFlags(videoflags);
 168                 } else
 169                 if ( strcmp(argv[argc], "-hw") == 0 ) {
 170                         videoflags ^= SDL_HWSURFACE;
 171                 } else
 172                 if ( strcmp(argv[argc], "-flip") == 0 ) {
 173                         videoflags ^= SDL_DOUBLEBUF;
 174                 } else
 175                 if ( strcmp(argv[argc], "-fullscreen") == 0 ) {
 176                         videoflags ^= SDL_FULLSCREEN;
 177                 } else
 178                 if ( isdigit(argv[argc][0]) ) {
 179                         numsprites = atoi(argv[argc]);
 180                 } else {
 181                         fprintf(stderr, 
 182         "Usage: %s [-bpp N] [-hw] [-flip] [-fast] [-fullscreen] [numsprites]\n",
 183                                                                 argv[0]);
 184                         exit(1);
 185                 }
 186         }
 188         /* Set video mode */
 189         screen = SDL_SetVideoMode(width, height, video_bpp, videoflags);
 190         if ( ! screen ) {
 191                 fprintf(stderr, "Couldn't set %dx%d video mode: %s\n",
 192                                         width, height, SDL_GetError());
 193                 exit(2);
 194         }
 196         /* Load the sprite */
 197         if ( LoadSprite(screen, "icon.bmp") < 0 ) {
 198                 exit(1);
 199         }
 201         /* Allocate memory for the sprite info */
 202         mem = (Uint8 *)malloc(4*sizeof(SDL_Rect)*numsprites);
 203         if ( mem == NULL ) {
SDL_FreeSurface(sprite);
 205                 fprintf(stderr, "Out of memory!\n");
 206                 exit(2);
 207         }
 208         sprite_rects = (SDL_Rect *)mem;
 209         positions = sprite_rects;
 210         sprite_rects += numsprites;
 211         velocities = sprite_rects;
 212         sprite_rects += numsprites;
 213         srand(time(NULL));
 214         for ( i=0; i<numsprites; ++i ) {
 215                 positions[i].x = rand()%screen->w;
 216                 positions[i].y = rand()%screen->h;
 217                 positions[i].w = sprite->w;
 218                 positions[i].h = sprite->h;
 219                 velocities[i].x = 0;
 220                 velocities[i].y = 0;
 221                 while ( ! velocities[i].x && ! velocities[i].y ) {
 222                         velocities[i].x = (rand()%(MAX_SPEED*2+1))-MAX_SPEED;
 223                         velocities[i].y = (rand()%(MAX_SPEED*2+1))-MAX_SPEED;
 224                 }
 225         }
 226         background = SDL_MapRGB(screen->format, 0x00, 0x00, 0x00);
 228         /* Print out information about our surfaces */
 229         printf("Screen is at %d bits per pixel\n",screen->format->BitsPerPixel);
 230         if ( (screen->flags & SDL_HWSURFACE) == SDL_HWSURFACE ) {
 231                 printf("Screen is in video memory\n");
 232         } else {
 233                 printf("Screen is in system memory\n");
 234         }
 235         if ( (screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF ) {
 236                 printf("Screen has double-buffering enabled\n");
 237         }
 238         if ( (sprite->flags & SDL_HWSURFACE) == SDL_HWSURFACE ) {
 239                 printf("Sprite is in video memory\n");
 240         } else {
 241                 printf("Sprite is in system memory\n");
 242         }
 243         /* Run a sample blit to trigger blit acceleration */
 244         { SDL_Rect dst;
 245                 dst.x = 0;
 246                 dst.y = 0;
 247                 dst.w = sprite->w;
 248                 dst.h = sprite->h;
 249                 SDL_BlitSurface(sprite, NULL, screen, &dst);
SDL_FillRect(screen, &dst, background);
 251         }
 252         if ( (sprite->flags & SDL_HWACCEL) == SDL_HWACCEL ) {
 253                 printf("Sprite blit uses hardware acceleration\n");
 254         }
 255         if ( (sprite->flags & SDL_RLEACCEL) == SDL_RLEACCEL ) {
 256                 printf("Sprite blit uses RLE acceleration\n");
 257         }
 259         /* Loop, blitting sprites and waiting for a keystroke */
 260         frames = 0;
 261         then = SDL_GetTicks();
 262         done = 0;
 263         sprites_visible = 0;
 264         while ( !done ) {
 265                 /* Check for events */
 266                 ++frames;
 267                 while ( SDL_PollEvent(&event) ) {
 268                         switch (event.type) {
 269                                 case SDL_KEYDOWN:
 270                                         /* Any keypress quits the app... */
 271                                 case SDL_QUIT:
 272                                         done = 1;
 273                                         break;
 274                                 default:
 275                                         break;
 276                         }
 277                 }
MoveSprites(screen, background);
 279         }
SDL_FreeSurface(sprite);
 281         free(mem);
 283         /* Print out some timing information */
 284         now = SDL_GetTicks();
 285         if ( now > then ) {
 286                 printf("%2.2f frames per second\n",
 287                                         ((double)frames*1000)/(now-then));
 288         }
 289         return(0);
 290 }