/*

 * 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>

#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_SetSurfacePalette(bg, screen->format->palette);

    /* 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;

    if (boatcols >= 256)

        sdlerr("too many colors in sail.bmp");

    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;

}