/*

* 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}

};

static void sdlerr(char *when)

{

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

exit(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");

atexit(SDL_Quit);

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");

return 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());

return 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));

return 0;

}