/*

  * testpalette.c

  *

  * A simple test of runtime palette modification for animation

  * (using the SDL_SetPalette() API). 

  */

 #include <stdio.h>

 #include <stdlib.h>

 #include <string.h>

 #include <math.h>

 /* This isn't in the Windows headers */

 #ifndef M_PI

 #define M_PI	3.14159265358979323846

 #endif

 #include "SDL.h"

 /* screen size */

 #define SCRW 640

 #define SCRH 480

 #define NBOATS 5

 #define SPEED 2

 #ifndef MIN

 #define MIN(a, b) ((a) < (b) ? (a) : (b))

 #endif

 #ifndef MAX

 #define MAX(a, b) ((a) > (b) ? (a) : (b))

 #endif

 /*

  * wave colours: Made by taking a narrow cross-section of a wave picture

  * in Gimp, saving in PPM ascii format and formatting with Emacs macros.

  */

 static SDL_Color wavemap[] = {

     {0, 2, 103}, {0, 7, 110}, {0, 13, 117}, {0, 19, 125},

     {0, 25, 133}, {0, 31, 141}, {0, 37, 150}, {0, 43, 158},

     {0, 49, 166}, {0, 55, 174}, {0, 61, 182}, {0, 67, 190},

     {0, 73, 198}, {0, 79, 206}, {0, 86, 214}, {0, 96, 220},

     {5, 105, 224}, {12, 112, 226}, {19, 120, 227}, {26, 128, 229},

     {33, 135, 230}, {40, 143, 232}, {47, 150, 234}, {54, 158, 236},

     {61, 165, 238}, {68, 173, 239}, {75, 180, 241}, {82, 188, 242},

     {89, 195, 244}, {96, 203, 246}, {103, 210, 248}, {112, 218, 250},

     {124, 224, 250}, {135, 226, 251}, {146, 229, 251}, {156, 231, 252},

     {167, 233, 252}, {178, 236, 252}, {189, 238, 252}, {200, 240, 252},

     {211, 242, 252}, {222, 244, 252}, {233, 247, 252}, {242, 249, 252},

     {237, 250, 252}, {209, 251, 252}, {174, 251, 252}, {138, 252, 252},

     {102, 251, 252}, {63, 250, 252}, {24, 243, 252}, {7, 225, 252},

     {4, 203, 252}, {3, 181, 252}, {2, 158, 252}, {1, 136, 251},

     {0, 111, 248}, {0, 82, 234}, {0, 63, 213}, {0, 50, 192},

     {0, 39, 172}, {0, 28, 152}, {0, 17, 132}, {0, 7, 114}

 };

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

 static void

 quit(int rc)

 {

     SDL_Quit();

     exit(rc);

 }

 static void

 sdlerr(char *when)

 {

     fprintf(stderr, "SDL error: %s: %s\n", when, SDL_GetError());

     quit(1);

 }

 /* create a background surface */

 static SDL_Surface *

 make_bg(SDL_Surface * screen, int startcol)

 {

     int i;

     SDL_Surface *bg =

         SDL_CreateRGBSurface(SDL_SWSURFACE, screen->w, screen->h,

                              8, 0, 0, 0, 0);

     if (!bg)

         sdlerr("creating background surface");

     /* set the palette to the logical screen palette so that blits

        won't be translated */

     SDL_SetColors(bg, screen->format->palette->colors, 0, 256);

     /* Make a wavy background pattern using colours 0-63 */

     if (SDL_LockSurface(bg) < 0)

         sdlerr("locking background");

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

         Uint8 *p = (Uint8 *) bg->pixels + i * bg->pitch;

         int j, d;

         d = 0;

         for (j = 0; j < SCRW; j++) {

             int v = MAX(d, -2);

             v = MIN(v, 2);

             if (i > 0)

                 v += p[-bg->pitch] + 65 - startcol;

             p[j] = startcol + (v & 63);

             d += ((rand() >> 3) % 3) - 1;

         }

     }

     SDL_UnlockSurface(bg);

     return (bg);

 }

 /*

  * Return a surface flipped horisontally. Only works for 8bpp;

  * extension to arbitrary bitness is left as an exercise for the reader.

  */

 static SDL_Surface *

 hflip(SDL_Surface * s)

 {

     int i;

     SDL_Surface *z = SDL_CreateRGBSurface(SDL_SWSURFACE, s->w, s->h, 8,

                                           0, 0, 0, 0);

     /* copy palette */

     SDL_SetColors(z, s->format->palette->colors,

                   0, s->format->palette->ncolors);

     if (SDL_LockSurface(s) < 0 || SDL_LockSurface(z) < 0)

         sdlerr("locking flip images");

     for (i = 0; i < s->h; i++) {

         int j;

         Uint8 *from = (Uint8 *) s->pixels + i * s->pitch;

         Uint8 *to = (Uint8 *) z->pixels + i * z->pitch + s->w - 1;

         for (j = 0; j < s->w; j++)

             to[-j] = from[j];

     }

     SDL_UnlockSurface(z);

     SDL_UnlockSurface(s);

     return z;

 }

 int

 main(int argc, char **argv)

 {

     SDL_Color cmap[256];

     SDL_Surface *screen;

     SDL_Surface *bg;

     SDL_Surface *boat[2];

     unsigned vidflags = 0;

     unsigned start;

     int fade_max = 400;

     int fade_level, fade_dir;

     int boatcols, frames, i, red;

     int boatx[NBOATS], boaty[NBOATS], boatdir[NBOATS];

     int gamma_fade = 0;

     int gamma_ramp = 0;

     if (SDL_Init(SDL_INIT_VIDEO) < 0)

         sdlerr("initialising SDL");

     while (--argc) {

         ++argv;

         if (strcmp(*argv, "-hw") == 0)

             vidflags |= SDL_HWSURFACE;

         else if (strcmp(*argv, "-fullscreen") == 0)

             vidflags |= SDL_FULLSCREEN;

         else if (strcmp(*argv, "-nofade") == 0)

             fade_max = 1;

         else if (strcmp(*argv, "-gamma") == 0)

             gamma_fade = 1;

         else if (strcmp(*argv, "-gammaramp") == 0)

             gamma_ramp = 1;

         else {

             fprintf(stderr,

                     "usage: testpalette "

                     " [-hw] [-fullscreen] [-nofade] [-gamma] [-gammaramp]\n");

             quit(1);

         }

     }

     /* Ask explicitly for 8bpp and a hardware palette */

     if ((screen =

          SDL_SetVideoMode(SCRW, SCRH, 8, vidflags | SDL_HWPALETTE)) == NULL) {

         fprintf(stderr, "error setting %dx%d 8bpp indexed mode: %s\n",

                 SCRW, SCRH, SDL_GetError());

         quit(1);

     }

     if (vidflags & SDL_FULLSCREEN)

         SDL_ShowCursor(SDL_FALSE);

     if ((boat[0] = SDL_LoadBMP("sail.bmp")) == NULL)

         sdlerr("loading sail.bmp");

     /* We've chosen magenta (#ff00ff) as colour key for the boat */

     SDL_SetColorKey(boat[0], SDL_SRCCOLORKEY | SDL_RLEACCEL,

                     SDL_MapRGB(boat[0]->format, 0xff, 0x00, 0xff));

     boatcols = boat[0]->format->palette->ncolors;

     boat[1] = hflip(boat[0]);

     SDL_SetColorKey(boat[1], SDL_SRCCOLORKEY | SDL_RLEACCEL,

                     SDL_MapRGB(boat[1]->format, 0xff, 0x00, 0xff));

     /*

      * First set the physical screen palette to black, so the user won't

      * see our initial drawing on the screen.

      */

     memset(cmap, 0, sizeof(cmap));

     SDL_SetPalette(screen, SDL_PHYSPAL, cmap, 0, 256);

     /*

      * Proper palette management is important when playing games with the

      * colormap. We have divided the palette as follows:

      *

      * index 0..(boatcols-1):           used for the boat

      * index boatcols..(boatcols+63):   used for the waves

      */

     SDL_SetPalette(screen, SDL_LOGPAL,

                    boat[0]->format->palette->colors, 0, boatcols);

     SDL_SetPalette(screen, SDL_LOGPAL, wavemap, boatcols, 64);

     /*

      * Now the logical screen palette is set, and will remain unchanged.

      * The boats already have the same palette so fast blits can be used.

      */

     memcpy(cmap, screen->format->palette->colors, 256 * sizeof(SDL_Color));

     /* save the index of the red colour for later */

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

     bg = make_bg(screen, boatcols);     /* make a nice wavy background surface */

     /* initial screen contents */

     if (SDL_BlitSurface(bg, NULL, screen, NULL) < 0)

         sdlerr("blitting background to screen");

     SDL_Flip(screen);           /* actually put the background on screen */

     /* determine initial boat placements */

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

         boatx[i] = (rand() % (SCRW + boat[0]->w)) - boat[0]->w;

         boaty[i] = i * (SCRH - boat[0]->h) / (NBOATS - 1);

         boatdir[i] = ((rand() >> 5) & 1) * 2 - 1;

     }

     start = SDL_GetTicks();

     frames = 0;

     fade_dir = 1;

     fade_level = 0;

     do {

         SDL_Event e;

         SDL_Rect updates[NBOATS];

         SDL_Rect r;

         int redphase;

         /* A small event loop: just exit on any key or mouse button event */

         while (SDL_PollEvent(&e)) {

             if (e.type == SDL_KEYDOWN || e.type == SDL_QUIT

                 || e.type == SDL_MOUSEBUTTONDOWN) {

                 if (fade_dir < 0)

                     fade_level = 0;

                 fade_dir = -1;

             }

         }

         /* move boats */

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

             int old_x = boatx[i];

             /* update boat position */

             boatx[i] += boatdir[i] * SPEED;

             if (boatx[i] <= -boat[0]->w || boatx[i] >= SCRW)

                 boatdir[i] = -boatdir[i];

             /* paint over the old boat position */

             r.x = old_x;

             r.y = boaty[i];

             r.w = boat[0]->w;

             r.h = boat[0]->h;

             if (SDL_BlitSurface(bg, &r, screen, &r) < 0)

                 sdlerr("blitting background");

             /* construct update rectangle (bounding box of old and new pos) */

             updates[i].x = MIN(old_x, boatx[i]);

             updates[i].y = boaty[i];

             updates[i].w = boat[0]->w + SPEED;

             updates[i].h = boat[0]->h;

             /* clip update rectangle to screen */

             if (updates[i].x < 0) {

                 updates[i].w += updates[i].x;

                 updates[i].x = 0;

             }

             if (updates[i].x + updates[i].w > SCRW)

                 updates[i].w = SCRW - updates[i].x;

         }

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

             /* paint boat on new position */

             r.x = boatx[i];

             r.y = boaty[i];

             if (SDL_BlitSurface(boat[(boatdir[i] + 1) / 2], NULL,

                                 screen, &r) < 0)

                 sdlerr("blitting boat");

         }

         /* cycle wave palette */

         for (i = 0; i < 64; i++)

             cmap[boatcols + ((i + frames) & 63)] = wavemap[i];

         if (fade_dir) {

             /* Fade the entire palette in/out */

             fade_level += fade_dir;

             if (gamma_fade) {

                 /* Fade linearly in gamma level (lousy) */

                 float level = (float) fade_level / fade_max;

                 if (SDL_SetGamma(level, level, level) < 0)

                     sdlerr("setting gamma");

             } else if (gamma_ramp) {

                 /* Fade using gamma ramp (better) */

                 Uint16 ramp[256];

                 for (i = 0; i < 256; i++)

                     ramp[i] = (i * fade_level / fade_max) << 8;

                 if (SDL_SetGammaRamp(ramp, ramp, ramp) < 0)

                     sdlerr("setting gamma ramp");

             } else {

                 /* Fade using direct palette manipulation (best) */

                 memcpy(cmap, screen->format->palette->colors,

                        boatcols * sizeof(SDL_Color));

                 for (i = 0; i < boatcols + 64; i++) {

                     cmap[i].r = cmap[i].r * fade_level / fade_max;

                     cmap[i].g = cmap[i].g * fade_level / fade_max;

                     cmap[i].b = cmap[i].b * fade_level / fade_max;

                 }

             }

             if (fade_level == fade_max)

                 fade_dir = 0;

         }

         /* pulse the red colour (done after the fade, for a night effect) */

         redphase = frames % 64;

         cmap[red].r = (int) (255 * sin(redphase * M_PI / 63));

         SDL_SetPalette(screen, SDL_PHYSPAL, cmap, 0, boatcols + 64);

         /* update changed areas of the screen */

         SDL_UpdateRects(screen, NBOATS, updates);

         frames++;

     }

     while (fade_level > 0);

     printf("%d frames, %.2f fps\n",

            frames, 1000.0 * frames / (SDL_GetTicks() - start));

     if (vidflags & SDL_FULLSCREEN)

         SDL_ShowCursor(SDL_TRUE);

     SDL_Quit();

     return 0;

 }