/*

 * 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))) {

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

		SCRW, SCRH, SDL_GetError());

	quit(1);

    }

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

	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));

    SDL_Quit();

    return 0;

}